Merge pull request #2690 from ehuss/bump-version

Update to 0.4.49

.eslintrc.json

@@ -0,0 +1,95 @@
+{
+    "env": {
+        "browser": true,
+        "node": true,
+        "es6": true
+    },
+    "extends": "eslint:recommended",
+    "globals": {
+        "module": "readonly",
+        "require": "readonly"
+    },
+    "parserOptions": {
+        "ecmaVersion": 2021,
+        "requireConfigFile": false,
+        "sourceType": "module"
+    },
+    "ignorePatterns": ["**min.js", "**/highlight.js", "**/playground_editor/*"],
+    "rules": {
+        "indent": [
+            "error",
+            4
+        ],
+        "linebreak-style": [
+            "error",
+            "unix"
+        ],
+        "quotes": [
+            "error",
+            "single"
+        ],
+        "semi": [
+            "error",
+            "always"
+        ],
+        "brace-style": [
+            "error",
+            "1tbs",
+            { "allowSingleLine": false }
+        ],
+        "curly": "error",
+        "no-trailing-spaces": "error",
+        "no-multi-spaces": "error",
+        "keyword-spacing": [
+            "error",
+            { "before": true, "after": true }
+        ],
+        "comma-spacing": [
+            "error",
+            { "before": false, "after": true }
+        ],
+        "arrow-spacing": [
+            "error",
+            { "before": true, "after": true }
+        ],
+        "key-spacing": [
+            "error",
+            { "beforeColon": false, "afterColon": true, "mode": "strict" }
+        ],
+        "func-call-spacing": ["error", "never"],
+        "space-infix-ops": "error",
+        "space-before-function-paren": ["error", "never"],
+        "space-before-blocks": "error",
+        "no-console": [
+            "error",
+            { "allow": ["warn", "error"] }
+        ],
+        "comma-dangle": ["error", "always-multiline"],
+        "comma-style": ["error", "last"],
+        "max-len": ["error", { "code": 100, "tabWidth": 2 }],
+        "eol-last": ["error", "always"],
+        "no-extra-parens": "error",
+        "arrow-parens": ["error", "as-needed"],
+        "no-unused-vars": [
+            "error",
+            {
+                "argsIgnorePattern": "^_",
+                "varsIgnorePattern": "^_"
+            }
+        ],
+        "prefer-const": ["error"],
+        "no-var": "error",
+        "eqeqeq": "error"
+    },
+    "overrides": [
+        {
+            "files": [
+                "tests/**/*.js"
+            ],
+            "env": {
+                "jest": true,
+                "node": true
+            }
+        }
+    ]
+}

.gitattributes

@@ -6,3 +6,5 @@
 *.ttf binary
 *.otf binary
 *.png binary
+*.eot binary
+*.woff2 binary

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,45 @@
+name: Bug Report
+description: Create a report to help us improve
+labels: ["C-bug"]
+body:
+  - type: markdown
+    attributes:
+      value: Thanks for filing a 🐛 bug report 😄!
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: >
+        Please provide a clear and concise description of what the bug is,
+        including what currently happens and what you expected to happen.
+    validations:
+      required: true
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps
+      description: Please list the steps to reproduce the bug.
+      placeholder: |
+        1.
+        2.
+        3.
+  - type: textarea
+    id: possible-solutions
+    attributes:
+      label: Possible Solution(s)
+      description: >
+        Not obligatory, but suggest a fix/reason for the bug,
+        or ideas how to implement the addition or change.
+  - type: textarea
+    id: notes
+    attributes:
+      label: Notes
+      description: Provide any additional notes that might be helpful.
+  - type: textarea
+    id: version
+    attributes:
+      label: Version
+      description: >
+        Please paste the output of running `mdbook --version` or which version
+        of the library you are using.
+      render: text

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,28 @@
+name: Enhancement
+description: Suggest an idea for enhancing mdBook
+labels: ["C-enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for filing a 🙋 feature request 😄!
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem
+      description: >
+        Please provide a clear description of your use case and the problem
+        this feature request is trying to solve.
+    validations:
+      required: true
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed Solution
+      description: >
+        Please provide a clear and concise description of what you want to happen.
+  - type: textarea
+    id: notes
+    attributes:
+      label: Notes
+      description: Provide any additional context or information that might be helpful.

.github/ISSUE_TEMPLATE/question.yml

@@ -0,0 +1,24 @@
+name: Question
+description: Have a question on how to use mdBook?
+labels: ["C-question"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Got a question on how to do something with mdBook?
+  - type: textarea
+    id: question
+    attributes:
+      label: Question
+      description: >
+        Enter your question here. Please try to provide as much detail as possible.
+    validations:
+      required: true
+  - type: textarea
+    id: version
+    attributes:
+      label: Version
+      description: >
+        Please paste the output of running `mdbook --version` or which version
+        of the library you are using.
+      render: text

.github/workflows/deploy.yml

@@ -3,36 +3,52 @@ on:
   release:
     types: [created]
 
+defaults:
+  run:
+    shell: bash
+
+permissions:
+  contents: write
+
 jobs:
   release:
-    name: Deploy Release
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        include:
+          - target: aarch64-unknown-linux-musl
+            os: ubuntu-22.04
+          - target: x86_64-unknown-linux-gnu
+            os: ubuntu-22.04
+          - target: x86_64-unknown-linux-musl
+            os: ubuntu-22.04
+          - target: x86_64-apple-darwin
+            os: macos-latest
+          - target: aarch64-apple-darwin
+            os: macos-latest
+          - target: x86_64-pc-windows-msvc
+            os: windows-latest
+    name: Deploy ${{ matrix.target }}
     steps:
-    - uses: actions/checkout@master
-    - name: Install hub
-      run: ci/install-hub.sh ${{ matrix.os }}
-      shell: bash
+    - uses: actions/checkout@v4
     - name: Install Rust
-      run: ci/install-rust.sh stable
-      shell: bash
-    - name: Build and deploy artifacts
+      run: ci/install-rust.sh stable ${{ matrix.target }}
+    - name: Build asset
+      run: ci/make-release-asset.sh ${{ matrix.os }} ${{ matrix.target }}
+    - name: Update release with new asset
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-      run: ci/make-release.sh ${{ matrix.os }}
-      shell: bash
+      run: gh release upload $MDBOOK_TAG $MDBOOK_ASSET
   pages:
     name: GitHub Pages
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v4
     - name: Install Rust (rustup)
       run: rustup update stable --no-self-update && rustup default stable
     - name: Build book
       run: cargo run -- build guide
-    - name: Deploy to GitHub
+    - name: Deploy the User Guide to GitHub Pages using the gh-pages branch
       env:
         GITHUB_DEPLOY_KEY: ${{ secrets.GITHUB_DEPLOY_KEY }}
       run: |
@@ -40,3 +56,14 @@ jobs:
         curl -LsSf https://raw.githubusercontent.com/rust-lang/simpleinfra/master/setup-deploy-keys/src/deploy.rs | rustc - -o /tmp/deploy
         cd guide/book
         /tmp/deploy
+  publish:
+    name: Publish to crates.io
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust (rustup)
+        run: rustup update stable --no-self-update && rustup default stable
+      - name: Publish
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+        run: cargo publish --no-verify

.github/workflows/main.yml

@@ -1,52 +1,132 @@
 name: CI
 on:
-  # Only run when merging to master, or open/synchronize/reopen a PR.
-  push:
-    branches:
-      - master
   pull_request:
+  merge_group:
 
 jobs:
   test:
-    name: Test
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        build: [stable, beta, nightly, macos, windows, msrv]
         include:
-          - build: stable
+          - name: stable linux
             os: ubuntu-latest
             rust: stable
-          - build: beta
+            target: x86_64-unknown-linux-gnu
+          - name: beta linux
             os: ubuntu-latest
             rust: beta
-          - build: nightly
+            target: x86_64-unknown-linux-gnu
+          - name: nightly linux
             os: ubuntu-latest
             rust: nightly
-          - build: macos
+            target: x86_64-unknown-linux-gnu
+          - name: stable x86_64-unknown-linux-musl
+            os: ubuntu-22.04
+            rust: stable
+            target: x86_64-unknown-linux-musl
+          - name: stable x86_64 macos
             os: macos-latest
             rust: stable
-          - build: windows
+            target: x86_64-apple-darwin
+          - name: stable aarch64 macos
+            os: macos-latest
+            rust: stable
+            target: aarch64-apple-darwin
+          - name: stable windows-msvc
             os: windows-latest
             rust: stable
-          - build: msrv
-            os: ubuntu-latest
-            # sync MSRV with docs: guide/src/guide/installation.md
-            rust: 1.54.0
+            target: x86_64-pc-windows-msvc
+          - name: msrv
+            os: ubuntu-22.04
+            # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
+            rust: 1.81.0
+            target: x86_64-unknown-linux-gnu
+    name: ${{ matrix.name }}
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v4
     - name: Install Rust
-      run: bash ci/install-rust.sh ${{ matrix.rust }}
+      run: bash ci/install-rust.sh ${{ matrix.rust }} ${{ matrix.target }}
     - name: Build and run tests
-      run: cargo test
+      run: cargo test --locked --target ${{ matrix.target }}
     - name: Test no default
-      run: cargo test --no-default-features
+      run: cargo test --no-default-features --target ${{ matrix.target }}
+
+  aarch64-cross-builds:
+    runs-on: ubuntu-22.04
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Rust
+      run: bash ci/install-rust.sh stable aarch64-unknown-linux-musl
+    - name: Build
+      run: cargo build --locked --target aarch64-unknown-linux-musl
 
   rustfmt:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v4
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup component add rustfmt
     - run: cargo fmt --check
+
+  gui:
+    name: GUI tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: bash ci/install-rust.sh stable x86_64-unknown-linux-gnu
+      - name: Install npm
+        uses: actions/setup-node@v3
+        with:
+          node-version: 20
+      - name: Install browser-ui-test
+        run: npm install
+      - name: Run eslint
+        run: npm run lint
+      - name: Build and run tests (+ GUI)
+        run: cargo test --locked --target x86_64-unknown-linux-gnu --test gui
+
+  # Ensure there are no clippy warnings
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: bash ci/install-rust.sh stable x86_64-unknown-linux-gnu
+      - run: rustup component add clippy
+      - run: cargo clippy --workspace --all-targets --no-deps -- -D warnings
+
+  docs:
+    name: Check API docs
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: bash ci/install-rust.sh stable x86_64-unknown-linux-gnu
+      - name: Ensure intradoc links are valid
+        run: cargo doc --workspace --document-private-items --no-deps
+        env:
+          RUSTDOCFLAGS: -D warnings
+
+  # The success job is here to consolidate the total success/failure state of
+  # all other jobs. This job is then included in the GitHub branch protection
+  # rule which prevents merges unless all other jobs are passing. This makes
+  # it easier to manage the list of jobs via this yml file and to prevent
+  # accidentally adding new jobs without also updating the branch protections.
+  success:
+    name: Success gate
+    if: always()
+    needs:
+      - test
+      - rustfmt
+      - aarch64-cross-builds
+      - gui
+      - clippy
+      - docs
+    runs-on: ubuntu-latest
+    steps:
+      - run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'
+      - name: Done
+        run: exit 0

.gitignore

@@ -9,6 +9,7 @@ guide/book
 .vscode
 tests/dummy_book/book/
 test_book/book/
+tests/testsuite/*/*/book/
 
 # Ignore Jetbrains specific files.
 .idea/
@@ -16,3 +17,8 @@ test_book/book/
 # Ignore Vim temporary and swap files.
 *.sw?
 *~
+
+# GUI tests
+node_modules
+package-lock.json
+package.json

CHANGELOG.md

@@ -1,5 +1,518 @@
 # Changelog
 
+## mdBook 0.4.49
+[v0.4.48...v0.4.49](https://github.com/rust-lang/mdBook/compare/v0.4.48...v0.4.49)
+
+### Added
+
+- Added a warning on unused fields in the root of `book.toml`.
+  [#2622](https://github.com/rust-lang/mdBook/pull/2622)
+
+### Changed
+
+- Updated dependencies.
+  [#2650](https://github.com/rust-lang/mdBook/pull/2650)
+  [#2688](https://github.com/rust-lang/mdBook/pull/2688)
+- Updated minimum Rust version to 1.81.
+  [#2688](https://github.com/rust-lang/mdBook/pull/2688)
+- The unused `book.multilingual` field is no longer serialized, or shown in `mdbook init`.
+  [#2689](https://github.com/rust-lang/mdBook/pull/2689)
+- Speed up search index loading by using `JSON.parse` instead of parsing JavaScript.
+  [#2633](https://github.com/rust-lang/mdBook/pull/2633)
+
+### Fixed
+
+- Search highlighting will not try to highlight in SVG `<text>` elements because it breaks the element.
+  [#2668](https://github.com/rust-lang/mdBook/pull/2668)
+- Fixed scrolling of the sidebar when a search highlight term is in the URL.
+  [#2675](https://github.com/rust-lang/mdBook/pull/2675)
+- Fixed issues when multiple footnote definitions use the same ID. Now, only one definition is used, and a warning is displayed.
+  [#2681](https://github.com/rust-lang/mdBook/pull/2681)
+- The sidebar is now restricted to 80% of the viewport width to make it possible to collapse it when the viewport is very narrow.
+  [#2679](https://github.com/rust-lang/mdBook/pull/2679)
+
+## mdBook 0.4.48
+[v0.4.47...v0.4.48](https://github.com/rust-lang/mdBook/compare/v0.4.47...v0.4.48)
+
+### Added
+
+- Footnotes now have back-reference links. These links bring the reader back to the original location. As part of this change, footnotes are now only rendered at the bottom of the page. This also includes some styling updates and fixes for footnote rendering.
+  [#2626](https://github.com/rust-lang/mdBook/pull/2626)
+- Added an "Auto" theme selection option which will default to the system-preferred mode. This will also automatically switch when the system changes the preferred mode.
+  [#2576](https://github.com/rust-lang/mdBook/pull/2576)
+
+### Changed
+
+- The `searchindex.json` file has been removed; only the `searchindex.js` file will be generated.
+  [#2552](https://github.com/rust-lang/mdBook/pull/2552)
+- Updated Javascript code to use eslint.
+  [#2554](https://github.com/rust-lang/mdBook/pull/2554)
+- An error is generated if there are duplicate files in `SUMMARY.md`.
+  [#2613](https://github.com/rust-lang/mdBook/pull/2613)
+
+## mdBook 0.4.47
+[v0.4.46...v0.4.47](https://github.com/rust-lang/mdBook/compare/v0.4.46...v0.4.47)
+
+### Fixed
+
+- Fixed search not showing up in sub-directories.
+  [#2586](https://github.com/rust-lang/mdBook/pull/2586)
+
+## mdBook 0.4.46
+[v0.4.45...v0.4.46](https://github.com/rust-lang/mdBook/compare/v0.4.45...v0.4.46)
+
+### Changed
+
+- The `output.html.hash-files` config option has been added to add hashes to static filenames to bust any caches when a book is updated. `{{resource}}` template tags have been added so that links can be properly generated to those files.
+  [#1368](https://github.com/rust-lang/mdBook/pull/1368)
+
+### Fixed
+
+- Playground links for Rust 2024 now set the edition correctly.
+  [#2557](https://github.com/rust-lang/mdBook/pull/2557)
+
+## mdBook 0.4.45
+[v0.4.44...v0.4.45](https://github.com/rust-lang/mdBook/compare/v0.4.44...v0.4.45)
+
+### Changed
+
+- Added context to error message when rustdoc is not found.
+  [#2545](https://github.com/rust-lang/mdBook/pull/2545)
+- Slightly changed the styling rules around margins of footnotes.
+  [#2524](https://github.com/rust-lang/mdBook/pull/2524)
+
+### Fixed
+
+- Fixed an issue where it would panic if a source_path is not set.
+  [#2550](https://github.com/rust-lang/mdBook/pull/2550)
+
+## mdBook 0.4.44
+[v0.4.43...v0.4.44](https://github.com/rust-lang/mdBook/compare/v0.4.43...v0.4.44)
+
+### Added
+
+- Added pre-built aarch64-apple-darwin binaries to the releases.
+  [#2500](https://github.com/rust-lang/mdBook/pull/2500)
+- `mdbook clean` now shows a summary of what it did.
+  [#2458](https://github.com/rust-lang/mdBook/pull/2458)
+- Added the `output.html.search.chapter` config setting to disable search indexing of individual chapters.
+  [#2533](https://github.com/rust-lang/mdBook/pull/2533)
+
+### Fixed
+
+- Fixed auto-scrolling the side-bar when loading a page with a `#` fragment URL.
+  [#2517](https://github.com/rust-lang/mdBook/pull/2517)
+- Fixed display of sidebar when javascript is disabled.
+  [#2529](https://github.com/rust-lang/mdBook/pull/2529)
+- Fixed the sidebar visibility getting out of sync with the button.
+  [#2532](https://github.com/rust-lang/mdBook/pull/2532)
+
+### Changed
+
+- ❗ Rust code block hidden lines now follow the same logic as rustdoc. This requires a space after the `#` symbol.
+  [#2530](https://github.com/rust-lang/mdBook/pull/2530)
+- ❗ Updated the Linux pre-built binaries which requires a newer version of glibc (2.34).
+  [#2523](https://github.com/rust-lang/mdBook/pull/2523)
+- Updated dependencies
+  [#2538](https://github.com/rust-lang/mdBook/pull/2538)
+  [#2539](https://github.com/rust-lang/mdBook/pull/2539)
+
+## mdBook 0.4.43
+[v0.4.42...v0.4.43](https://github.com/rust-lang/mdBook/compare/v0.4.42...v0.4.43)
+
+### Fixed
+
+- Fixed setting the title in `mdbook init` when no git user is configured.
+  [#2486](https://github.com/rust-lang/mdBook/pull/2486)
+
+### Changed
+
+- The Rust 2024 edition no longer needs `-Zunstable-options`.
+  [#2495](https://github.com/rust-lang/mdBook/pull/2495)
+
+## mdBook 0.4.42
+[v0.4.41...v0.4.42](https://github.com/rust-lang/mdBook/compare/v0.4.41...v0.4.42)
+
+### Fixed
+
+- Fixed chapter list folding.
+  [#2473](https://github.com/rust-lang/mdBook/pull/2473)
+
+## mdBook 0.4.41
+[v0.4.40...v0.4.41](https://github.com/rust-lang/mdBook/compare/v0.4.40...v0.4.41)
+
+**Note:** If you have a custom `index.hbs` theme file, you will need to update it to the latest version.
+
+### Added
+
+- Added preliminary support for Rust 2024 edition.
+  [#2398](https://github.com/rust-lang/mdBook/pull/2398)
+- Added a full example of the remove-emphasis preprocessor.
+  [#2464](https://github.com/rust-lang/mdBook/pull/2464)
+
+### Changed
+
+- Adjusted styling of clipboard/play icons.
+  [#2421](https://github.com/rust-lang/mdBook/pull/2421)
+- Updated to handlebars v6.
+  [#2416](https://github.com/rust-lang/mdBook/pull/2416)
+- Attr and section rules now have specific code highlighting.
+  [#2448](https://github.com/rust-lang/mdBook/pull/2448)
+- The sidebar is now loaded from a common file, significantly reducing the book size when there are many chapters.
+  [#2414](https://github.com/rust-lang/mdBook/pull/2414)
+- Updated dependencies.
+  [#2470](https://github.com/rust-lang/mdBook/pull/2470)
+
+### Fixed
+
+- Improved theme support when JavaScript is disabled.
+  [#2454](https://github.com/rust-lang/mdBook/pull/2454)
+- Fixed broken themes when localStorage has an invalid theme id.
+  [#2463](https://github.com/rust-lang/mdBook/pull/2463)
+- Adjusted the line-height of superscripts (and footnotes) to avoid adding extra space between lines.
+  [#2465](https://github.com/rust-lang/mdBook/pull/2465)
+
+## mdBook 0.4.40
+[v0.4.39...v0.4.40](https://github.com/rust-lang/mdBook/compare/v0.4.39...v0.4.40)
+
+### Fixed
+
+- Reverted the update to pulldown-cmark which broke the semver API.
+  [#2388](https://github.com/rust-lang/mdBook/pull/2388)
+
+## mdBook 0.4.39
+[v0.4.38...v0.4.39](https://github.com/rust-lang/mdBook/compare/v0.4.38...v0.4.39)
+
+### Fixed
+
+- Fixed the automatic deploy broken in the previous release.
+  [#2383](https://github.com/rust-lang/mdBook/pull/2383)
+
+## mdBook 0.4.38
+[v0.4.37...v0.4.38](https://github.com/rust-lang/mdBook/compare/v0.4.37...v0.4.38)
+
+### Added
+
+- Added `nix` to the default set of languages supported for syntax highlighting.
+  [#2262](https://github.com/rust-lang/mdBook/pull/2262)
+
+### Changed
+
+- The `output.html.curly-quotes` option has been renamed to `output.html.smart-punctuation` to better reflect what it does. The old option `curly-quotes` is kept for compatibility, but may be removed in the future.
+  [#2327](https://github.com/rust-lang/mdBook/pull/2327)
+- The file-watcher used in `mdbook serve` and `mdbook watch` now uses a poll-based watcher instead of the native operating system notifications. This should fix issues on various systems and environments, and more accurately detect when files change. The native watcher can still be used with the `--watcher native` CLI option.
+  [#2325](https://github.com/rust-lang/mdBook/pull/2325)
+- `mdbook test` output now includes color, and shows relative paths to the source.
+  [#2259](https://github.com/rust-lang/mdBook/pull/2259)
+- Updated dependencies, MSRV raised to 1.74
+  [#2350](https://github.com/rust-lang/mdBook/pull/2350)
+  [#2351](https://github.com/rust-lang/mdBook/pull/2351)
+  [#2378](https://github.com/rust-lang/mdBook/pull/2378)
+  [#2381](https://github.com/rust-lang/mdBook/pull/2381)
+
+### Fixed
+
+- Reduced memory allocation when copying files.
+  [#2355](https://github.com/rust-lang/mdBook/pull/2355)
+- Fixed the horizontal divider in `SUMMARY.md` from being indented into the previous nested section.
+  [#2364](https://github.com/rust-lang/mdBook/pull/2364)
+- Removed unnecessary `@import` in the CSS.
+  [#2260](https://github.com/rust-lang/mdBook/pull/2260)
+
+## mdBook 0.4.37
+[v0.4.36...v0.4.37](https://github.com/rust-lang/mdBook/compare/v0.4.36...v0.4.37)
+
+### Changed
+- ❗️ Updated the markdown parser. This brings in many changes to more closely follow the CommonMark spec. This may cause some small rendering changes. It is recommended to compare the output of the old and new version to check for changes. See <https://github.com/raphlinus/pulldown-cmark/releases/tag/v0.10.0> for more information.
+  [#2308](https://github.com/rust-lang/mdBook/pull/2308)
+- The warning about the legacy `src/theme` directory has been removed.
+  [#2263](https://github.com/rust-lang/mdBook/pull/2263)
+- Updated dependencies. MSRV raised to 1.71.0.
+  [#2283](https://github.com/rust-lang/mdBook/pull/2283)
+  [#2293](https://github.com/rust-lang/mdBook/pull/2293)
+  [#2297](https://github.com/rust-lang/mdBook/pull/2297)
+  [#2310](https://github.com/rust-lang/mdBook/pull/2310)
+  [#2309](https://github.com/rust-lang/mdBook/pull/2309)
+- Some internal performance/memory improvements.
+  [#2273](https://github.com/rust-lang/mdBook/pull/2273)
+  [#2290](https://github.com/rust-lang/mdBook/pull/2290)
+- Made the `pathdiff` dependency optional based on the `watch` feature.
+  [#2291](https://github.com/rust-lang/mdBook/pull/2291)
+
+### Fixed
+- The `s` shortcut key handler should not trigger when focus is in an HTML form.
+  [#2311](https://github.com/rust-lang/mdBook/pull/2311)
+
+## mdBook 0.4.36
+[v0.4.35...v0.4.36](https://github.com/rust-lang/mdBook/compare/v0.4.35...v0.4.36)
+
+### Added
+- Added Nim to the default highlighted languages.
+  [#2232](https://github.com/rust-lang/mdBook/pull/2232)
+- Added a small indicator for the sidebar resize handle.
+  [#2209](https://github.com/rust-lang/mdBook/pull/2209)
+
+### Changed
+- Updated dependencies. MSRV raised to 1.70.0.
+  [#2173](https://github.com/rust-lang/mdBook/pull/2173)
+  [#2250](https://github.com/rust-lang/mdBook/pull/2250)
+  [#2252](https://github.com/rust-lang/mdBook/pull/2252)
+
+### Fixed
+- Fixed blank column in print page when the sidebar was visible.
+  [#2235](https://github.com/rust-lang/mdBook/pull/2235)
+- Fixed indentation of code blocks when Javascript is disabled.
+  [#2162](https://github.com/rust-lang/mdBook/pull/2162)
+- Fixed a panic when `mdbook serve` or `mdbook watch` were given certain kinds of paths.
+  [#2229](https://github.com/rust-lang/mdBook/pull/2229)
+
+## mdBook 0.4.35
+[v0.4.34...v0.4.35](https://github.com/rust-lang/mdBook/compare/v0.4.34...v0.4.35)
+
+### Added
+- Added the `book.text-direction` setting for explicit support for right-to-left languages.
+  [#1641](https://github.com/rust-lang/mdBook/pull/1641)
+- Added `rel=prefetch` to the "next" links to potentially improve browser performance.
+  [#2168](https://github.com/rust-lang/mdBook/pull/2168)
+- Added a `.warning` CSS class which is styled for displaying warning blocks.
+  [#2187](https://github.com/rust-lang/mdBook/pull/2187)
+
+### Changed
+- Better support of the sidebar when JavaScript is disabled.
+  [#2175](https://github.com/rust-lang/mdBook/pull/2175)
+
+## mdBook 0.4.34
+[v0.4.33...v0.4.34](https://github.com/rust-lang/mdBook/compare/v0.4.33...v0.4.34)
+
+### Fixed
+- Fixed file change watcher failing on macOS with a large number of files.
+  [#2157](https://github.com/rust-lang/mdBook/pull/2157)
+
+## mdBook 0.4.33
+[v0.4.32...v0.4.33](https://github.com/rust-lang/mdBook/compare/v0.4.32...v0.4.33)
+
+### Added
+- The `color-scheme` CSS property is now set based on the light/dark theme, which applies some slight color differences in browser elements like scroll bars on some browsers.
+  [#2134](https://github.com/rust-lang/mdBook/pull/2134)
+
+### Fixed
+- Fixed watching of extra-watch-dirs when not running in the book root directory.
+  [#2146](https://github.com/rust-lang/mdBook/pull/2146)
+- Reverted the dependency update to the `toml` crate (again!). This was an unintentional breaking change in 0.4.32.
+  [#2021](https://github.com/rust-lang/mdBook/pull/2021)
+- Changed macOS change notifications to use the kqueue implementation which should fix some issues with repeated rebuilds when a file changed.
+  [#2152](https://github.com/rust-lang/mdBook/pull/2152)
+- Don't set a background color in the print page for code blocks in a header.
+  [#2150](https://github.com/rust-lang/mdBook/pull/2150)
+
+## mdBook 0.4.32
+[v0.4.31...v0.4.32](https://github.com/rust-lang/mdBook/compare/v0.4.31...v0.4.32)
+
+### Fixed
+- Fixed theme-color meta tag not syncing with the theme.
+  [#2118](https://github.com/rust-lang/mdBook/pull/2118)
+
+### Changed
+- Updated all dependencies.
+  [#2121](https://github.com/rust-lang/mdBook/pull/2121)
+  [#2122](https://github.com/rust-lang/mdBook/pull/2122)
+  [#2123](https://github.com/rust-lang/mdBook/pull/2123)
+  [#2124](https://github.com/rust-lang/mdBook/pull/2124)
+  [#2125](https://github.com/rust-lang/mdBook/pull/2125)
+  [#2126](https://github.com/rust-lang/mdBook/pull/2126)
+
+## mdBook 0.4.31
+[v0.4.30...v0.4.31](https://github.com/rust-lang/mdBook/compare/v0.4.30...v0.4.31)
+
+### Fixed
+- Fixed menu border render flash during page navigation.
+  [#2101](https://github.com/rust-lang/mdBook/pull/2101)
+- Fixed flicker setting sidebar scroll position.
+  [#2104](https://github.com/rust-lang/mdBook/pull/2104)
+- Fixed compile error with proc-macro2 on latest Rust nightly.
+  [#2109](https://github.com/rust-lang/mdBook/pull/2109)
+
+## mdBook 0.4.30
+[v0.4.29...v0.4.30](https://github.com/rust-lang/mdBook/compare/v0.4.29...v0.4.30)
+
+### Added
+- Added support for heading attributes.
+  Attributes are specified in curly braces just after the heading text.
+  An HTML ID can be specified with `#` and classes with `.`.
+  For example: `## My heading {#custom-id .class1 .class2}`
+  [#2013](https://github.com/rust-lang/mdBook/pull/2013)
+- Added support for hidden code lines for languages other than Rust.
+  The `output.html.code.hidelines` table allows you to define the prefix character that will be used to hide code lines based on the language.
+  [#2093](https://github.com/rust-lang/mdBook/pull/2093)
+
+### Fixed
+- Fixed a few minor markdown rendering issues.
+  [#2092](https://github.com/rust-lang/mdBook/pull/2092)
+
+## mdBook 0.4.29
+[v0.4.28...v0.4.29](https://github.com/rust-lang/mdBook/compare/v0.4.28...v0.4.29)
+
+### Changed
+- Built-in fonts are no longer copied when `fonts/fonts.css` is overridden in the theme directory.
+  Additionally, the warning about `copy-fonts` has been removed if `fonts/fonts.css` is specified.
+  [#2080](https://github.com/rust-lang/mdBook/pull/2080)
+- `mdbook init --force` now skips all interactive prompts as intended.
+  [#2057](https://github.com/rust-lang/mdBook/pull/2057)
+- Updated dependencies
+  [#2063](https://github.com/rust-lang/mdBook/pull/2063)
+  [#2086](https://github.com/rust-lang/mdBook/pull/2086)
+  [#2082](https://github.com/rust-lang/mdBook/pull/2082)
+  [#2084](https://github.com/rust-lang/mdBook/pull/2084)
+  [#2085](https://github.com/rust-lang/mdBook/pull/2085)
+
+### Fixed
+- Switched from the `gitignore` library to `ignore`. This should bring some improvements with gitignore handling.
+  [#2076](https://github.com/rust-lang/mdBook/pull/2076)
+
+## mdBook 0.4.28
+[v0.4.27...v0.4.28](https://github.com/rust-lang/mdBook/compare/v0.4.27...v0.4.28)
+
+### Changed
+- The sidebar is now shown on wide screens when localstorage is disabled.
+  [#2017](https://github.com/rust-lang/mdBook/pull/2017)
+- Preprocessors are now run with `mdbook test`.
+  [#1986](https://github.com/rust-lang/mdBook/pull/1986)
+
+### Fixed
+- Fixed regression in 0.4.26 that prevented the title bar from scrolling properly on smaller screens.
+  [#2039](https://github.com/rust-lang/mdBook/pull/2039)
+
+## mdBook 0.4.27
+[v0.4.26...v0.4.27](https://github.com/rust-lang/mdBook/compare/v0.4.26...v0.4.27)
+
+### Changed
+- Reverted the dependency update to the `toml` crate. This was an unintentional breaking change in 0.4.26.
+  [#2021](https://github.com/rust-lang/mdBook/pull/2021)
+
+## mdBook 0.4.26
+[v0.4.25...v0.4.26](https://github.com/rust-lang/mdBook/compare/v0.4.25...v0.4.26)
+
+**The 0.4.26 release has been yanked due to an unintentional breaking change.**
+
+### Changed
+- Removed custom scrollbars for webkit browsers
+  [#1961](https://github.com/rust-lang/mdBook/pull/1961)
+- Updated some dependencies
+  [#1998](https://github.com/rust-lang/mdBook/pull/1998)
+  [#2009](https://github.com/rust-lang/mdBook/pull/2009)
+  [#2011](https://github.com/rust-lang/mdBook/pull/2011)
+- Fonts are now part of the theme.
+  The `output.html.copy-fonts` option has been deprecated.
+  To define custom fonts, be sure to define `theme/fonts.css`.
+  [#1987](https://github.com/rust-lang/mdBook/pull/1987)
+
+### Fixed
+- Fixed overflow viewport issue with mobile Safari
+  [#1994](https://github.com/rust-lang/mdBook/pull/1994)
+
+## mdBook 0.4.25
+[e14d381...1ba74a3](https://github.com/rust-lang/mdBook/compare/e14d381...1ba74a3)
+
+### Fixed
+- Fixed a regression where `mdbook test -L deps path-to-book` would not work.
+  [#1959](https://github.com/rust-lang/mdBook/pull/1959)
+
+## mdBook 0.4.24
+[eb77083...8767ebf](https://github.com/rust-lang/mdBook/compare/eb77083...8767ebf)
+
+### Fixed
+- The precompiled linux-gnu mdbook binary available on [GitHub Releases](https://github.com/rust-lang/mdBook/releases) inadvertently switched to a newer version of glibc. This release goes back to an older version that should be more compatible on older versions of Linux.
+  [#1955](https://github.com/rust-lang/mdBook/pull/1955)
+
+## mdBook 0.4.23
+[678b469...68a75da](https://github.com/rust-lang/mdBook/compare/678b469...68a75da)
+
+### Changed
+- Updated all dependencies
+  [#1951](https://github.com/rust-lang/mdBook/pull/1951)
+  [#1952](https://github.com/rust-lang/mdBook/pull/1952)
+  [#1844](https://github.com/rust-lang/mdBook/pull/1844)
+- Updated minimum Rust version to 1.60.
+  [#1951](https://github.com/rust-lang/mdBook/pull/1951)
+
+### Fixed
+- Fixed a regression where playground code was missing hidden lines, preventing it from compiling correctly.
+  [#1950](https://github.com/rust-lang/mdBook/pull/1950)
+
+## mdBook 0.4.22
+[40c06f5...4844f72](https://github.com/rust-lang/mdBook/compare/40c06f5...4844f72)
+
+### Added
+- Added a `--chapter` option to `mdbook test` to specify a specific chapter to test.
+  [#1741](https://github.com/rust-lang/mdBook/pull/1741)
+- Added CSS styling for `<kbd>` tags.
+  [#1906](https://github.com/rust-lang/mdBook/pull/1906)
+- Added pre-compiled binaries for `x86_64-unknown-linux-musl` and `aarch64-unknown-linux-musl` (see [Releases](https://github.com/rust-lang/mdBook/releases)).
+  [#1862](https://github.com/rust-lang/mdBook/pull/1862)
+- Added `build.extra-watch-dirs` which is an array of additional directories to watch for changes when running `mdbook serve`.
+  [#1884](https://github.com/rust-lang/mdBook/pull/1884)
+
+### Changed
+- Removed the `type="text/javascript"` attribute from `<script>` tags.
+  [#1881](https://github.com/rust-lang/mdBook/pull/1881)
+- Switched to building with Rust Edition 2021.
+  This raises the minimum supported Rust version to 1.56.
+  [#1887](https://github.com/rust-lang/mdBook/pull/1887)
+- When hidden code is hidden, the hidden parts are no longer copied to the clipboard via the copy button.
+  [#1911](https://github.com/rust-lang/mdBook/pull/1911)
+- Various HTML changes and fixes to be more compliant with HTML5.
+  [#1924](https://github.com/rust-lang/mdBook/pull/1924)
+- The theme picker now shows which theme is currently selected.
+  [#1935](https://github.com/rust-lang/mdBook/pull/1935)
+
+### Fixed
+- Avoid blank line at the end of an ACE code block
+  [#1836](https://github.com/rust-lang/mdBook/pull/1836)
+
+
+## mdBook 0.4.21
+[92afe9b...8f01d02](https://github.com/rust-lang/mdBook/compare/92afe9b...8f01d02)
+
+### Fixed
+- Fixed an issue where mdBook would fail to compile with Rust nightly-2022-07-22.
+  [#1861](https://github.com/rust-lang/mdBook/pull/1861)
+
+## mdBook 0.4.20
+[53055e0...da166e0](https://github.com/rust-lang/mdBook/compare/53055e0...da166e0)
+
+### Fixed
+- Fixed a regression in 0.4.19 where inline code would have excessive padding
+  in some situations such as headings.
+  [#1855](https://github.com/rust-lang/mdBook/pull/1855)
+
+## mdBook 0.4.19
+[ae275ad...53055e0](https://github.com/rust-lang/mdBook/compare/ae275ad...53055e0)
+
+### Added
+- The `serve` command now supports HEAD requests.
+  [#1825](https://github.com/rust-lang/mdBook/pull/1825)
+
+### Changed
+- An error is now generated when a custom theme directory does not exist.
+  [#1791](https://github.com/rust-lang/mdBook/pull/1791)
+- Very wide tables now have independent horizontal scrolling so that scrolling
+  to see the rest of the table will not scroll the entire page.
+  [#1617](https://github.com/rust-lang/mdBook/pull/1617)
+- The buttons on code blocks are now only shown when the mouse cursor hovers
+  over them (or tapped on mobile). There is also some extra spacing to reduce
+  the overlap with the code.
+  [#1806](https://github.com/rust-lang/mdBook/pull/1806)
+- The first chapter always generates an `index.html` file. Previously it would
+  only generate the index file for prefix chapters.
+  [#1829](https://github.com/rust-lang/mdBook/pull/1829)
+
+### Fixed
+- `mdbook serve --open` now properly handles the case if the first chapter is a draft.
+  [#1714](https://github.com/rust-lang/mdBook/pull/1714)
+  [#1830](https://github.com/rust-lang/mdBook/pull/1830)
+- Very long words (over 80 characters) are no longer indexed to avoid a stack overflow.
+  [#1833](https://github.com/rust-lang/mdBook/pull/1833)
+
 ## mdBook 0.4.18
 [981b79b...ae275ad](https://github.com/rust-lang/mdBook/compare/981b79b...ae275ad)
 
@@ -27,12 +540,12 @@
   [#1546](https://github.com/rust-lang/mdBook/pull/1546)
 
 ### Changed
-- The `cargo serve` live reload websocket now uses the protocol, host, and
+- The `mdbook serve` live reload websocket now uses the protocol, host, and
   port of the current page, allowing access through a proxy.
   [#1771](https://github.com/rust-lang/mdBook/pull/1771)
 - The 404 not-found page now includes the books title in the HTML title tag.
   [#1693](https://github.com/rust-lang/mdBook/pull/1693)
-- Migrated to clap 3.0 which which handles CLI option parsing.
+- Migrated to clap 3.0 which handles CLI option parsing.
   [#1731](https://github.com/rust-lang/mdBook/pull/1731)
 
 ### Fixed

CONTRIBUTING.md

@@ -7,13 +7,22 @@ If you have come here to learn how to contribute to mdBook, we have some tips fo
 First of all, don't hesitate to ask questions!
 Use the [issue tracker](https://github.com/rust-lang/mdBook/issues), no question is too simple.
 
+### Issue assignment
+
+**:warning: Important :warning:**
+
+Before working on pull request, please ping us on the corresponding issue.
+The current PR backlog is beyond what we can process at this time.
+Only issues that have an [`E-Help-wanted`](https://github.com/rust-lang/mdBook/labels/E-Help-wanted) or [`Feature accepted`](https://github.com/rust-lang/mdBook/labels/Feature%20accepted) label will likely receive reviews.
+If there isn't already an open issue for what you want to work on, please open one first to see if it is something we would be available to review.
+
 ### Issues to work on
 
-Any issue is up for the grabbing, but if you are starting out, you might be interested in the
+If you are starting out, you might be interested in the
 [E-Easy issues](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AE-Easy).
 Those are issues that are considered more straightforward for beginners to Rust or the codebase itself.
-These issues can be a good launching pad for more involved issues. Easy tasks for a first time contribution
-include documentation improvements, new tests, examples, updating dependencies, etc.
+These issues can be a good launching pad for more involved issues.
+Easy tasks for a first time contribution include documentation improvements, new tests, examples, updating dependencies, etc.
 
 If you come from a web development background, you might be interested in issues related to web technologies tagged
 [A-JavaScript](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-JavaScript),
@@ -21,16 +30,16 @@ If you come from a web development background, you might be interested in issues
 [A-HTML](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-HTML) or
 [A-Mobile](https://github.com/rust-lang/mdBook/issues?q=is%3Aopen+is%3Aissue+label%3AA-Mobile).
 
-When you decide you want to work on a specific issue, ping us on that issue so that we can assign it to you.
+When you decide you want to work on a specific issue, and it isn't already assigned to someone else, assign the issue to yourself by leaving a comment with the text `@rustbot claim`.
 Again, do not hesitate to ask questions. We will gladly mentor anyone that want to tackle an issue.
 
 Issues on the issue tracker are categorized with the following labels:
 
 - **A**-prefixed labels state which area of the project an issue relates to.
 - **E**-prefixed labels show an estimate of the experience necessary to fix the issue.
-- **M**-prefixed labels are meta-issues used for questions, discussions, or tracking issues
+- **M**-prefixed labels are meta-issues regarding the management of the mdBook project itself
 - **S**-prefixed labels show the status of the issue
-- **T**-prefixed labels show the type of issue
+- **C**-prefixed labels show the category of issue
 
 ### Building mdBook
 
@@ -59,7 +68,7 @@ This will ensure we have good quality source code that is better for us all to m
 [rustfmt](https://github.com/rust-lang/rustfmt) has a lot more information on the project.
 The quick guide is
 
-1. Install it
+1. Install it (`rustfmt` is usually installed by default via [rustup](https://rustup.rs/)):
     ```
     rustup component add rustfmt
     ```
@@ -71,18 +80,15 @@ The quick guide is
    ```
    cargo fmt
    ```
-   When run through `cargo` it will format all bin and lib files in the current crate.
+   When run through `cargo` it will format all bin and lib files in the current package.
 
 For more information, such as running it from your favourite editor, please see the `rustfmt` project. [rustfmt](https://github.com/rust-lang/rustfmt)
 
 
 #### Finding Issues with Clippy
 
-Clippy is a code analyser/linter detecting mistakes, and therefore helps to improve your code.
-Like formatting your code with `rustfmt`, running clippy regularly and before your Pull Request will
-help us maintain awesome code.
-
-The best documentation can be found over at [rust-clippy](https://github.com/rust-lang/rust-clippy)
+[Clippy](https://doc.rust-lang.org/clippy/) is a code analyser/linter detecting mistakes, and therefore helps to improve your code.
+Like formatting your code with `rustfmt`, running clippy regularly and before your Pull Request will help us maintain awesome code.
 
 1. To install
     ```
@@ -93,17 +99,36 @@ The best documentation can be found over at [rust-clippy](https://github.com/rus
     cargo clippy
     ```
 
-Clippy has an ever growing list of checks, that are managed in [lint files](https://rust-lang.github.io/rust-clippy/master/index.html).
+### Change requirements
+
+Please consider the following when making a change:
+
+* Almost all changes that modify the Rust code must be accompanied with a test.
+
+* Almost all features and changes must update the documentation.
+  mdBook has the [mdBook Guide](https://rust-lang.github.io/mdBook/) whose source is at <https://github.com/rust-lang/mdBook/tree/master/guide>.
+
+* Almost all Rust items should be documented with doc comments.
+  See the [Rustdoc Book](https://doc.rust-lang.org/rustdoc/) for more information on writing doc comments.
+
+* Breaking the API can only be done in major SemVer releases.
+  These are done very infrequently, so it is preferred to avoid these when possible.
+  See [SemVer Compatibility](https://doc.rust-lang.org/cargo/reference/semver.html) for more information on what a SemVer breaking change is.
+
+  (Note: At this time, some SemVer breaking changes are inevitable due to the current code structure.
+  An example is adding new fields to the config structures.
+  These are intended to be fixed in the next major release.)
+
+* Similarly, the CLI interface is considered to be stable.
+  Care should be taken to avoid breaking existing workflows.
+
+* Check out the [Rust API Guidelines](https://rust-lang.github.io/api-guidelines/) for guidelines on designing the API.
 
 ### Making a pull-request
 
 When you feel comfortable that your changes could be integrated into mdBook, you can create a pull-request on GitHub.
 One of the core maintainers will then approve the changes or request some changes before it gets merged.
 
-If you want to make your pull-request even better, you might want to run [Clippy](https://github.com/Manishearth/rust-clippy)
-and [rustfmt](https://github.com/rust-lang/rustfmt) on the code first.
-This is not a requirement though and will never block a pull-request from being merged.
-
 That's it, happy contributions! :tada: :tada: :tada:
 
 ## Browser compatibility and testing
@@ -113,18 +138,75 @@ We generally strive to keep mdBook compatible with a relatively recent browser o
 That is, supporting Chrome, Safari, Firefox, Edge on Windows, macOS, Linux, iOS, and Android.
 If possible, do your best to avoid breaking older browser releases.
 
-Any change to the HTML or styling is encouraged to manually check on as many browsers and platforms that you can.
-Unfortunately at this time we don't have any automated UI or browser testing, so your assistance in testing is appreciated.
+GUI tests are checked with the GUI testsuite. To run it, you need to install `npm` first. Then run:
 
-## Updating higlight.js
+```
+cargo test --test gui
+```
+
+If you want to only run some tests, you can filter them by passing (part of) their name:
+
+```
+cargo test --test gui -- search
+```
+
+The first time, it'll fail and ask you to install the `browser-ui-test` package. Install it with the provided
+command then re-run the tests.
+
+If you want to disable the headless mode, use the `--disable-headless-test` option:
+
+```
+cargo test --test gui -- --disable-headless-test
+```
+
+The GUI tests are in the directory `tests/gui` in text files with the `.goml` extension. These tests are run
+using a `node.js` framework called `browser-ui-test`. You can find documentation for this language on its
+[repository](https://github.com/GuillaumeGomez/browser-UI-test/blob/master/goml-script.md).
+
+### Checking changes in `.js` files
+
+The `.js` files source code is checked using [`eslint`](https://eslint.org/). This is a linter (just like `clippy` in Rust)
+for the Javascript language. You can install it with `npm` by running the following command:
+
+```
+npm install
+```
+
+Then you can run it using:
+
+```
+npm run lint
+```
+
+## Updating highlight.js
 
 The following are instructions for updating [highlight.js](https://highlightjs.org/).
 
 1. Clone the repository at <https://github.com/highlightjs/highlight.js>
 1. Check out a tagged release (like `10.1.1`).
 1. Run `npm install`
-1. Run `node tools/build.js :common apache armasm coffeescript d handlebars haskell http julia nginx properties r scala x86asm yaml`
+1. Run `node tools/build.js :common apache armasm coffeescript d handlebars haskell http julia nginx nim nix properties r scala x86asm yaml`
 1. Compare the language list that it spits out to the one in [`syntax-highlighting.md`](https://github.com/camelid/mdBook/blob/master/guide/src/format/theme/syntax-highlighting.md). If any are missing, add them to the list and rebuild (and update these docs). If any are added to the common set, add them to `syntax-highlighting.md`.
 1. Copy `build/highlight.min.js` to mdbook's directory [`highlight.js`](https://github.com/rust-lang/mdBook/blob/master/src/theme/highlight.js).
 1. Be sure to check the highlight.js [CHANGES](https://github.com/highlightjs/highlight.js/blob/main/CHANGES.md) for any breaking changes. Breaking changes that would affect users will need to wait until the next major release.
 1. Build mdbook with the new file and build some books with the new version and compare the output with a variety of languages to see if anything changes. The [test_book](https://github.com/rust-lang/mdBook/tree/master/test_book) contains a chapter with many languages to examine.
+
+## Publishing new releases
+
+Instructions for mdBook maintainers to publish a new release:
+
+1. Create a PR to update the version and update the CHANGELOG:
+    1. Update the version in `Cargo.toml`
+    2. Run `cargo test` to verify that everything is passing, and to update `Cargo.lock`.
+    3. Double-check for any SemVer breaking changes.
+       Try [`cargo-semver-checks`](https://crates.io/crates/cargo-semver-checks), though beware that the current version of mdBook isn't properly adhering to SemVer due to the lack of `#[non_exhaustive]` and other issues. See https://github.com/rust-lang/mdBook/issues/1835.
+    4. Update `CHANGELOG.md` with any changes that users may be interested in.
+    5. Update `continuous-integration.md` to update the version number for the installation instructions.
+    6. Commit the changes, and open a PR.
+2. After the PR has been merged, create a release in GitHub. This can either be done in the GitHub web UI, or on the command-line:
+   ```bash
+   MDBOOK_VERS="`cargo read-manifest | jq -r .version`" ; \
+    gh release create -R rust-lang/mdbook v$MDBOOK_VERS \
+        --title v$MDBOOK_VERS \
+        --notes "See https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-${MDBOOK_VERS//.} for a complete list of changes."
+   ```

Cargo.toml

@@ -1,68 +1,101 @@
+[workspace]
+members = [".", "examples/remove-emphasis/mdbook-remove-emphasis"]
+
+[workspace.lints.clippy]
+all = { level = "allow", priority = -2 }
+correctness = { level = "warn", priority = -1 }
+complexity = { level = "warn", priority = -1 }
+needless-lifetimes = "allow"  # Remove once 1.87 is stable, https://github.com/rust-lang/rust-clippy/issues/13514
+
 [package]
 name = "mdbook"
-version = "0.4.18"
+version = "0.4.49"
 authors = [
     "Mathieu David <mathieudavid@mathieudavid.org>",
     "Michael-F-Bryan <michaelfbryan@gmail.com>",
     "Matt Ickstadt <mattico8@gmail.com>"
 ]
-documentation = "http://rust-lang.github.io/mdBook/index.html"
-edition = "2018"
+documentation = "https://rust-lang.github.io/mdBook/index.html"
+edition = "2021"
 exclude = ["/guide/*"]
 keywords = ["book", "gitbook", "rustbook", "markdown"]
 license = "MPL-2.0"
 readme = "README.md"
 repository = "https://github.com/rust-lang/mdBook"
 description = "Creates a book from markdown files"
+rust-version = "1.81" # Keep in sync with installation.md and .github/workflows/main.yml
 
 [dependencies]
-anyhow = "1.0.28"
-chrono = "0.4"
-clap = { version = "3.0", features = ["cargo"] }
-clap_complete = "3.0"
-env_logger = "0.7.1"
-handlebars = "4.0"
-lazy_static = "1.0"
-log = "0.4"
-memchr = "2.0"
-opener = "0.5"
-pulldown-cmark = { version = "0.9.1", default-features = false }
-regex = "1.5.5"
-serde = "1.0"
-serde_derive = "1.0"
-serde_json = "1.0"
-shlex = "1"
-tempfile = "3.0"
-toml = "0.5.1"
-topological-sort = "0.1.0"
+anyhow = "1.0.71"
+chrono = { version = "0.4.24", default-features = false, features = ["clock"] }
+clap = { version = "4.3.12", features = ["cargo", "wrap_help"] }
+clap_complete = "4.3.2"
+once_cell = "1.17.1"
+env_logger = "0.11.1"
+handlebars = "6.0"
+hex = "0.4.3"
+log = "0.4.17"
+memchr = "2.5.0"
+opener = "0.7.0"
+pulldown-cmark = { version = "0.10.0", default-features = false, features = ["html"] } # Do not update, part of the public api.
+regex = "1.8.1"
+serde = { version = "1.0.163", features = ["derive"] }
+serde_json = "1.0.96"
+sha2 = "0.10.8"
+shlex = "1.3.0"
+tempfile = "3.4.0"
+toml = "0.5.11" # Do not update, see https://github.com/rust-lang/mdBook/issues/2037
+topological-sort = "0.2.2"
 
 # Watch feature
-notify = { version = "4.0", optional = true }
-gitignore = { version = "1.0", optional = true }
+notify = { version = "8.0.0", optional = true }
+notify-debouncer-mini = { version = "0.6.0", optional = true }
+ignore = { version = "0.4.20", optional = true }
+pathdiff = { version = "0.2.1", optional = true }
+walkdir = { version = "2.3.3", optional = true }
 
 # Serve feature
-futures-util = { version = "0.3.4", optional = true }
-tokio = { version = "1", features = ["macros", "rt-multi-thread"], optional = true }
-warp = { version = "0.3.1", default-features = false, features = ["websocket"], optional = true }
+futures-util = { version = "0.3.28", optional = true }
+tokio = { version = "1.43.1", features = ["macros", "rt-multi-thread"], optional = true }
+warp = { version = "0.3.6", default-features = false, features = ["websocket"], optional = true }
 
 # Search feature
-elasticlunr-rs = { version = "2.3", optional = true, default-features = false }
-ammonia = { version = "3", optional = true }
+elasticlunr-rs = { version = "3.0.2", optional = true }
+ammonia = { version = "4.0.0", optional = true }
 
 [dev-dependencies]
-assert_cmd = "1"
-predicates = "2"
-select = "0.5"
-semver = "1.0"
-pretty_assertions = "0.6"
-walkdir = "2.0"
+select = "0.6.0"
+semver = "1.0.17"
+snapbox = { version = "0.6.21", features = ["diff", "dir", "term-svg", "regex", "json"] }
+pretty_assertions = "1.3.0"
+walkdir = "2.3.3"
 
 [features]
 default = ["watch", "serve", "search"]
-watch = ["notify", "gitignore"]
-serve = ["futures-util", "tokio", "warp"]
-search = ["elasticlunr-rs", "ammonia"]
+watch = ["dep:notify", "dep:notify-debouncer-mini", "dep:ignore", "dep:pathdiff", "dep:walkdir"]
+serve = ["dep:futures-util", "dep:tokio", "dep:warp"]
+search = ["dep:elasticlunr-rs", "dep:ammonia"]
 
 [[bin]]
 doc = false
 name = "mdbook"
+
+[[example]]
+name = "nop-preprocessor"
+test = true
+
+[[example]]
+name = "remove-emphasis"
+path = "examples/remove-emphasis/test.rs"
+crate-type = ["lib"]
+test = true
+
+[[test]]
+harness = false
+test = false
+name = "gui"
+path = "tests/gui/runner.rs"
+crate-type = ["bin"]
+
+[lints]
+workspace = true

README.md

@@ -1,6 +1,6 @@
 # mdBook
 
-[![Build Status](https://github.com/rust-lang/mdBook/workflows/CI/badge.svg?event=push)](https://github.com/rust-lang/mdBook/actions?workflow=CI)
+[![CI Status](https://github.com/rust-lang/mdBook/actions/workflows/main.yml/badge.svg)](https://github.com/rust-lang/mdBook/actions/workflows/main.yml)
 [![crates.io](https://img.shields.io/crates/v/mdbook.svg)](https://crates.io/crates/mdbook)
 [![LICENSE](https://img.shields.io/github/license/rust-lang/mdBook.svg)](LICENSE)
 

ci/install-hub.sh

@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-# Installs the `hub` executable into hub/bin
-set -ex
-case $1 in
-  ubuntu*)
-    curl -LsSf https://github.com/github/hub/releases/download/v2.12.8/hub-linux-amd64-2.12.8.tgz -o hub.tgz
-    mkdir hub
-    tar -xzvf hub.tgz --strip=1 -C hub
-    ;;
-  macos*)
-    curl -LsSf https://github.com/github/hub/releases/download/v2.12.8/hub-darwin-amd64-2.12.8.tgz -o hub.tgz
-    mkdir hub
-    tar -xzvf hub.tgz --strip=1 -C hub
-    ;;
-  windows*)
-    curl -LsSf https://github.com/github/hub/releases/download/v2.12.8/hub-windows-amd64-2.12.8.zip -o hub.zip
-    7z x hub.zip -ohub
-    ;;
-  *)
-    echo "OS should be first parameter, was: $1"
-    ;;
-esac
-
-echo "$PWD/hub/bin" >> $GITHUB_PATH

ci/install-rust.sh

@@ -13,6 +13,30 @@ TOOLCHAIN="$1"
 rustup set profile minimal
 rustup component remove --toolchain=$TOOLCHAIN rust-docs || echo "already removed"
 rustup update --no-self-update $TOOLCHAIN
+if [ -n "$2" ]
+then
+    TARGET="$2"
+    HOST=$(rustc -Vv | grep ^host: | sed -e "s/host: //g")
+    if [ "$HOST" != "$TARGET" ]
+    then
+        rustup component add llvm-tools-preview --toolchain=$TOOLCHAIN
+        rustup component add rust-std-$TARGET --toolchain=$TOOLCHAIN
+    fi
+    if [[ $TARGET == *"musl" ]]
+    then
+        # This is needed by libdbus-sys.
+        sudo apt update -y && sudo apt install musl-dev musl-tools -y
+    fi
+    if [[ $TARGET == "aarch64-unknown-linux-musl" ]]
+    then
+        echo CARGO_TARGET_AARCH64_UNKNOWN_LINUX_MUSL_LINKER=rust-lld >> $GITHUB_ENV
+        # This `CC` is some nonsense needed for libdbus-sys (via opener).
+        # I don't know if this is really the right thing to do, but it seems to work.
+        sudo apt install gcc-aarch64-linux-gnu -y
+        echo CC=aarch64-linux-gnu-gcc >> $GITHUB_ENV
+    fi
+fi
+
 rustup default $TOOLCHAIN
 rustup -V
 rustc -Vv

ci/make-release-asset.sh

@@ -11,16 +11,17 @@ fi
 TAG=${GITHUB_REF#*/tags/}
 
 host=$(rustc -Vv | grep ^host: | sed -e "s/host: //g")
+target=$2
 export CARGO_PROFILE_RELEASE_LTO=true
-cargo build --bin mdbook --release
-cd target/release
+cargo build --locked --bin mdbook --release --target $target
+cd target/$target/release
 case $1 in
   ubuntu*)
-    asset="mdbook-$TAG-$host.tar.gz"
+    asset="mdbook-$TAG-$target.tar.gz"
     tar czf ../../$asset mdbook
     ;;
   macos*)
-    asset="mdbook-$TAG-$host.tar.gz"
+    asset="mdbook-$TAG-$target.tar.gz"
     # There is a bug with BSD tar on macOS where the first 8MB of the file are
     # sometimes all NUL bytes. See https://github.com/actions/cache/issues/403
     # and https://github.com/rust-lang/cargo/issues/8603 for some more
@@ -30,7 +31,7 @@ case $1 in
     tar czf ../../$asset mdbook
     ;;
   windows*)
-    asset="mdbook-$TAG-$host.zip"
+    asset="mdbook-$TAG-$target.zip"
     7z a ../../$asset mdbook.exe
     ;;
   *)
@@ -39,9 +40,10 @@ case $1 in
 esac
 cd ../..
 
-if [[ -z "$GITHUB_TOKEN" ]]
+if [[ -z "$GITHUB_ENV" ]]
 then
-  echo "$GITHUB_TOKEN not set, skipping deploy."
+  echo "GITHUB_ENV not set, run: gh release upload $TAG target/$asset"
 else
-  hub release edit -m "" --attach $asset $TAG
+  echo "MDBOOK_TAG=$TAG" >> $GITHUB_ENV
+  echo "MDBOOK_ASSET=target/$asset" >> $GITHUB_ENV
 fi

examples/nop-preprocessor.rs

@@ -1,5 +1,5 @@
 use crate::nop_lib::Nop;
-use clap::{App, Arg, ArgMatches};
+use clap::{Arg, ArgMatches, Command};
 use mdbook::book::Book;
 use mdbook::errors::Error;
 use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext};
@@ -7,11 +7,11 @@ use semver::{Version, VersionReq};
 use std::io;
 use std::process;
 
-pub fn make_app() -> App<'static> {
-    App::new("nop-preprocessor")
+pub fn make_app() -> Command {
+    Command::new("nop-preprocessor")
         .about("A mdbook preprocessor which does precisely nothing")
         .subcommand(
-            App::new("supports")
+            Command::new("supports")
                 .arg(Arg::new("renderer").required(true))
                 .about("Check whether a renderer is supported by this preprocessor"),
         )
@@ -26,7 +26,7 @@ fn main() {
     if let Some(sub_args) = matches.subcommand_matches("supports") {
         handle_supports(&preprocessor, sub_args);
     } else if let Err(e) = handle_preprocessing(&preprocessor) {
-        eprintln!("{}", e);
+        eprintln!("{e:?}");
         process::exit(1);
     }
 }
@@ -54,7 +54,9 @@ fn handle_preprocessing(pre: &dyn Preprocessor) -> Result<(), Error> {
 }
 
 fn handle_supports(pre: &dyn Preprocessor, sub_args: &ArgMatches) -> ! {
-    let renderer = sub_args.value_of("renderer").expect("Required argument");
+    let renderer = sub_args
+        .get_one::<String>("renderer")
+        .expect("Required argument");
     let supported = pre.supports_renderer(renderer);
 
     // Signal whether the renderer is supported by exiting with 1 or 0.
@@ -101,4 +103,58 @@ mod nop_lib {
             renderer != "not-supported"
         }
     }
+
+    #[cfg(test)]
+    mod test {
+        use super::*;
+
+        #[test]
+        fn nop_preprocessor_run() {
+            let input_json = r##"[
+                {
+                    "root": "/path/to/book",
+                    "config": {
+                        "book": {
+                            "authors": ["AUTHOR"],
+                            "language": "en",
+                            "multilingual": false,
+                            "src": "src",
+                            "title": "TITLE"
+                        },
+                        "preprocessor": {
+                            "nop": {}
+                        }
+                    },
+                    "renderer": "html",
+                    "mdbook_version": "0.4.21"
+                },
+                {
+                    "sections": [
+                        {
+                            "Chapter": {
+                                "name": "Chapter 1",
+                                "content": "# Chapter 1\n",
+                                "number": [1],
+                                "sub_items": [],
+                                "path": "chapter_1.md",
+                                "source_path": "chapter_1.md",
+                                "parent_names": []
+                            }
+                        }
+                    ],
+                    "__non_exhaustive": null
+                }
+            ]"##;
+            let input_json = input_json.as_bytes();
+
+            let (ctx, book) = mdbook::preprocess::CmdPreprocessor::parse_input(input_json).unwrap();
+            let expected_book = book.clone();
+            let result = Nop::new().run(&ctx, book);
+            assert!(result.is_ok());
+
+            // The nop-preprocessor should not have made any changes to the book content.
+            let actual_book = result.unwrap();
+            assert_eq!(actual_book, expected_book);
+        }
+    }
 }

examples/remove-emphasis/.gitignore

@@ -0,0 +1 @@
+book

examples/remove-emphasis/book.toml

@@ -0,0 +1,5 @@
+[book]
+title = "remove-emphasis"
+
+[preprocessor.remove-emphasis]
+command = "cargo run --manifest-path=mdbook-remove-emphasis/Cargo.toml --locked"

examples/remove-emphasis/mdbook-remove-emphasis/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "mdbook-remove-emphasis"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+mdbook = { version = "0.4.40", path = "../../.." }
+pulldown-cmark = { version = "0.12.2", default-features = false }
+pulldown-cmark-to-cmark = "18.0.0"
+serde_json = "1.0.132"

examples/remove-emphasis/mdbook-remove-emphasis/src/main.rs

@@ -0,0 +1,82 @@
+//! This is a demonstration of an mdBook preprocessor which parses markdown
+//! and removes any instances of emphasis.
+
+use mdbook::book::{Book, Chapter};
+use mdbook::errors::Error;
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext};
+use mdbook::BookItem;
+use pulldown_cmark::{Event, Parser, Tag, TagEnd};
+use std::io;
+
+fn main() {
+    let mut args = std::env::args().skip(1);
+    match args.next().as_deref() {
+        Some("supports") => {
+            // Supports all renderers.
+            return;
+        }
+        Some(arg) => {
+            eprintln!("unknown argument: {arg}");
+            std::process::exit(1);
+        }
+        None => {}
+    }
+
+    if let Err(e) = handle_preprocessing() {
+        eprintln!("{}", e);
+        std::process::exit(1);
+    }
+}
+
+struct RemoveEmphasis;
+
+impl Preprocessor for RemoveEmphasis {
+    fn name(&self) -> &str {
+        "remove-emphasis"
+    }
+
+    fn run(&self, _ctx: &PreprocessorContext, mut book: Book) -> Result<Book, Error> {
+        let mut total = 0;
+        book.for_each_mut(|item| {
+            let BookItem::Chapter(ch) = item else {
+                return;
+            };
+            if ch.is_draft_chapter() {
+                return;
+            }
+            match remove_emphasis(&mut total, ch) {
+                Ok(s) => ch.content = s,
+                Err(e) => eprintln!("failed to process chapter: {e:?}"),
+            }
+        });
+        eprintln!("removed {total} emphasis");
+        Ok(book)
+    }
+}
+
+// ANCHOR: remove_emphasis
+fn remove_emphasis(num_removed_items: &mut usize, chapter: &mut Chapter) -> Result<String, Error> {
+    let mut buf = String::with_capacity(chapter.content.len());
+
+    let events = Parser::new(&chapter.content).filter(|e| match e {
+        Event::Start(Tag::Emphasis) | Event::Start(Tag::Strong) => {
+            *num_removed_items += 1;
+            false
+        }
+        Event::End(TagEnd::Emphasis) | Event::End(TagEnd::Strong) => false,
+        _ => true,
+    });
+
+    Ok(pulldown_cmark_to_cmark::cmark(events, &mut buf).map(|_| buf)?)
+}
+// ANCHOR_END: remove_emphasis
+
+pub fn handle_preprocessing() -> Result<(), Error> {
+    let pre = RemoveEmphasis;
+    let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())?;
+
+    let processed_book = pre.run(&ctx, book)?;
+    serde_json::to_writer(io::stdout(), &processed_book)?;
+
+    Ok(())
+}

examples/remove-emphasis/src/SUMMARY.md

@@ -0,0 +1,3 @@
+# Summary
+
+- [Chapter 1](./chapter_1.md)

examples/remove-emphasis/src/chapter_1.md

@@ -0,0 +1,3 @@
+# Chapter 1
+
+This has *light emphasis* and **bold emphasis**.

examples/remove-emphasis/test.rs

@@ -0,0 +1,11 @@
+#[test]
+fn remove_emphasis_works() {
+    // Tests that the remove-emphasis example works as expected.
+
+    // Workaround for https://github.com/rust-lang/mdBook/issues/1424
+    std::env::set_current_dir("examples/remove-emphasis").unwrap();
+    let book = mdbook::MDBook::load(".").unwrap();
+    book.build().unwrap();
+    let ch1 = std::fs::read_to_string("book/chapter_1.html").unwrap();
+    assert!(ch1.contains("This has light emphasis and bold emphasis."));
+}

guide/book.toml

@@ -8,15 +8,20 @@ language = "en"
 edition = "2018"
 
 [output.html]
+smart-punctuation = true
 mathjax-support = true
 site-url = "/mdBook/"
 git-repository-url = "https://github.com/rust-lang/mdBook/tree/master/guide"
 edit-url-template = "https://github.com/rust-lang/mdBook/edit/master/guide/{path}"
+hash-files = true
 
 [output.html.playground]
 editable = true
 line-numbers = true
 
+[output.html.code.hidelines]
+python = "~"
+
 [output.html.search]
 limit-results = 20
 use-boolean-and = true

guide/src/cli/README.md

@@ -5,10 +5,10 @@ After you have [installed](../guide/installation.md) `mdbook`, you can run the `
 
 This following sections provide in-depth information on the different commands available.
 
-* [`mdbook init <directory>`](init.md) — Creates a new book with minimal boilerplate to start with.
-* [`mdbook build`](build.md) — Renders the book.
-* [`mdbook watch`](watch.md) — Rebuilds the book any time a source file changes.
-* [`mdbook serve`](serve.md) — Runs a web server to view the book, and rebuilds on changes.
-* [`mdbook test`](test.md) — Tests Rust code samples.
-* [`mdbook clean`](clean.md) — Deletes the rendered output.
-* [`mdbook completions`](completions.md) — Support for shell auto-completion.
+* [`mdbook init <directory>`](init.md) --- Creates a new book with minimal boilerplate to start with.
+* [`mdbook build`](build.md) --- Renders the book.
+* [`mdbook watch`](watch.md) --- Rebuilds the book any time a source file changes.
+* [`mdbook serve`](serve.md) --- Runs a web server to view the book, and rebuilds on changes.
+* [`mdbook test`](test.md) --- Tests Rust code samples.
+* [`mdbook clean`](clean.md) --- Deletes the rendered output.
+* [`mdbook completions`](completions.md) --- Support for shell auto-completion.

guide/src/cli/arg-watcher.md

@@ -0,0 +1,7 @@
+#### `--watcher`
+
+There are different backends used to determine when a file has changed.
+
+* `poll` (default) --- Checks for file modifications by scanning the filesystem every second.
+* `native` --- Uses the native operating system facilities to receive notifications when files change.
+  This can have less constant overhead, but may not be as reliable as the `poll` based watcher. See these issues for more information: [#383](https://github.com/rust-lang/mdBook/issues/383) [#1441](https://github.com/rust-lang/mdBook/issues/1441) [#1707](https://github.com/rust-lang/mdBook/issues/1707) [#2035](https://github.com/rust-lang/mdBook/issues/2035) [#2102](https://github.com/rust-lang/mdBook/issues/2102)

guide/src/cli/build.md

@@ -7,8 +7,8 @@ mdbook build
 ```
 
 It will try to parse your `SUMMARY.md` file to understand the structure of your
-book and fetch the corresponding files. Note that files mentioned in `SUMMARY.md`
-but not present will be created.
+book and fetch the corresponding files. Note that this will also create files
+mentioned in `SUMMARY.md` which are not yet present.
 
 The rendered output will maintain the same directory structure as the source for
 convenience. Large books will therefore remain structured when rendered.
@@ -22,12 +22,12 @@ root instead of the current working directory.
 mdbook build path/to/book
 ```
 
-#### --open
+#### `--open`
 
 When you use the `--open` (`-o`) flag, mdbook will open the rendered book in
 your default web browser after building it.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If

guide/src/cli/clean.md

@@ -16,7 +16,7 @@ root instead of the current working directory.
 mdbook clean path/to/book
 ```
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to override the book's output
 directory, which will be deleted by this command. Relative paths are interpreted
@@ -27,4 +27,4 @@ value of the `build.build-dir` key in `book.toml`, or to `./book`.
 mdbook clean --dest-dir=path/to/book
 ```
 
-`path/to/book` could be absolute or relative.
+`path/to/book` could be absolute or relative.

guide/src/cli/completions.md

@@ -6,7 +6,11 @@ This means when you type `mdbook` in your shell, you can then press your shell's
 The completions first need to be installed for your shell:
 
 ```bash
+# bash
 mdbook completions bash > ~/.local/share/bash-completion/completions/mdbook
+# oh-my-zsh
+mdbook completions zsh > ~/.oh-my-zsh/completions/_mdbook
+autoload -U compinit && compinit
 ```
 
 The command prints a completion script for the given shell.

guide/src/cli/init.md

@@ -45,7 +45,7 @@ instead of the current working directory.
 mdbook init path/to/book
 ```
 
-#### --theme
+#### `--theme`
 
 When you use the `--theme` flag, the default theme will be copied into a
 directory called `theme` in your source directory so that you can modify it.
@@ -53,7 +53,7 @@ directory called `theme` in your source directory so that you can modify it.
 The theme is selectively overwritten, this means that if you don't want to
 overwrite a specific file, just delete it and the default file will be used.
 
-#### --title
+#### `--title`
 
 Specify a title for the book. If not supplied, an interactive prompt will ask for 
 a title. 
@@ -62,9 +62,21 @@ a title.
 mdbook init --title="my amazing book"
 ```
 
-#### --ignore
+#### `--ignore`
 
 Create a `.gitignore` file configured to ignore the `book` directory created when [building] a book. 
 If not supplied, an interactive prompt will ask whether it should be created.
 
+```bash
+mdbook init --ignore=none
+```
+
+```bash
+mdbook init --ignore=git
+```
+
 [building]: build.md
+
+#### `--force`
+
+Skip the prompts to create a `.gitignore` and for the title for the book.

guide/src/cli/serve.md

@@ -32,18 +32,20 @@ The `serve` hostname defaults to `localhost`, and the port defaults to `3000`. E
 mdbook serve path/to/book -p 8000 -n 127.0.0.1 
 ```
 
-#### --open
+#### `--open`
 
 When you use the `--open` (`-o`) flag, mdbook will open the book in your
 default web browser after starting the server.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If
 not specified it will default to the value of the `build.build-dir` key in
 `book.toml`, or to `./book`.
 
+{{#include arg-watcher.md}}
+
 #### Specify exclude patterns
 
 The `serve` command will not automatically trigger a build for files listed in

guide/src/cli/test.md

@@ -6,8 +6,7 @@ of code examples that could get outdated. Therefore it is very important for
 them to be able to automatically test these code examples.
 
 mdBook supports a `test` command that will run all available tests in a book. At
-the moment, only rustdoc tests are supported, but this may be expanded upon in
-the future.
+the moment, only Rust tests are supported.
 
 #### Disable tests on a code block
 
@@ -38,12 +37,12 @@ instead of the current working directory.
 mdbook test path/to/book
 ```
 
-#### --library-path
+#### `--library-path`
 
 The `--library-path` (`-L`) option allows you to add directories to the library
 search path used by `rustdoc` when it builds and tests the examples. Multiple
 directories can be specified with multiple options (`-L foo -L bar`) or with a
-comma-delimited list (`-L foo,bar`). The path should point to the Cargo 
+comma-delimited list (`-L foo,bar`). The path should point to the Cargo
 [build cache](https://doc.rust-lang.org/cargo/guide/build-cache.html) `deps` directory that
 contains the build output of your project. For example, if your Rust project's book is in a directory
 named `my-book`, the following command would include the crate's dependencies when running `test`:
@@ -55,9 +54,14 @@ mdbook test my-book -L target/debug/deps/
 See the `rustdoc` command-line [documentation](https://doc.rust-lang.org/rustdoc/command-line-arguments.html#-l--library-path-where-to-look-for-dependencies)
 for more information.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If
 not specified it will default to the value of the `build.build-dir` key in
 `book.toml`, or to `./book`.
+
+#### `--chapter`
+
+The `--chapter` (`-c`) option allows you to test a specific chapter of the
+book using the chapter name or the relative path to the chapter.

guide/src/cli/watch.md

@@ -15,18 +15,19 @@ root instead of the current working directory.
 mdbook watch path/to/book
 ```
 
-#### --open
+#### `--open`
 
 When you use the `--open` (`-o`) option, mdbook will open the rendered book in
 your default web browser.
 
-#### --dest-dir
+#### `--dest-dir`
 
 The `--dest-dir` (`-d`) option allows you to change the output directory for the
 book. Relative paths are interpreted relative to the book's root directory. If
 not specified it will default to the value of the `build.build-dir` key in
 `book.toml`, or to `./book`.
 
+{{#include arg-watcher.md}}
 
 #### Specify exclude patterns
 

guide/src/continuous-integration.md

@@ -21,7 +21,7 @@ A simple approach would be to use the popular `curl` CLI tool to download the ex
 
 ```sh
 mkdir bin
-curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.18/mdbook-v0.4.18-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.49/mdbook-v0.4.49-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
 bin/mdbook build
 ```
 
@@ -51,13 +51,13 @@ cargo install mdbook --no-default-features --features search --vers "^0.4" --loc
 
 This includes several recommended options:
 
-* `--no-default-features` — Disables features like the HTTP server used by `mdbook serve` that is likely not needed on CI.
+* `--no-default-features` --- Disables features like the HTTP server used by `mdbook serve` that is likely not needed on CI.
   This will speed up the build time significantly.
-* `--features search` — Disabling default features means you should then manually enable features that you want, such as the built-in [search] capability.
-* `--vers "^0.4"` — This will install the most recent version of the `0.4` series.
+* `--features search` --- Disabling default features means you should then manually enable features that you want, such as the built-in [search] capability.
+* `--vers "^0.4"` --- This will install the most recent version of the `0.4` series.
   However, versions after like `0.5.0` won't be installed, as they may break your build.
   Cargo will automatically upgrade mdBook if you have an older version already installed.
-* `--locked` — This will use the dependencies that were used when mdBook was released.
+* `--locked` --- This will use the dependencies that were used when mdBook was released.
   Without `--locked`, it will use the latest version of all dependencies, which may include some fixes since the last release, but may also (rarely) cause build problems.
 
 You will likely want to investigate caching options, as building mdBook can be somewhat slow.
@@ -83,7 +83,7 @@ Or if you have your own style checks, spell checker, or any other tests it might
 ## Deploying
 
 You may want to automatically deploy your book.
-Some may want to do this with every time a change is pushed, and others may want to only deploy when a specific release is tagged.
+Some may want to do this every time a change is pushed, and others may want to only deploy when a specific release is tagged.
 
 You'll also need to understand the specifics on how to push a change to your web service.
 For example, [GitHub Pages] just requires committing the output onto a specific git branch.

guide/src/for_developers/backends.md

@@ -287,7 +287,7 @@ like this:
 +             if cfg.deny_odds && num_words % 2 == 1 {
 +               eprintln!("{} has an odd number of words!", ch.name);
 +               process::exit(1);
-              }
++             }
           }
       }
   }

guide/src/for_developers/preprocessors.md

@@ -68,33 +68,10 @@ The following code block shows how to remove all emphasis from markdown,
 without accidentally breaking the document.
 
 ```rust
-fn remove_emphasis(
-    num_removed_items: &mut usize,
-    chapter: &mut Chapter,
-) -> Result<String> {
-    let mut buf = String::with_capacity(chapter.content.len());
-
-    let events = Parser::new(&chapter.content).filter(|e| {
-        let should_keep = match *e {
-            Event::Start(Tag::Emphasis)
-            | Event::Start(Tag::Strong)
-            | Event::End(Tag::Emphasis)
-            | Event::End(Tag::Strong) => false,
-            _ => true,
-        };
-        if !should_keep {
-            *num_removed_items += 1;
-        }
-        should_keep
-    });
-
-    cmark(events, &mut buf, None).map(|_| buf).map_err(|err| {
-        Error::from(format!("Markdown serialization failed: {}", err))
-    })
-}
+{{#rustdoc_include ../../../examples/remove-emphasis/mdbook-remove-emphasis/src/main.rs:remove_emphasis}}
 ```
 
-For everything else, have a look [at the complete example][example].
+Take a look at the [full example source][emphasis-example] for more details.
 
 ## Implementing a preprocessor with a different language
 
@@ -122,11 +99,10 @@ if __name__ == '__main__':
 ```
 
 
-
+[emphasis-example]: https://github.com/rust-lang/mdBook/tree/master/examples/remove-emphasis/
 [preprocessor-docs]: https://docs.rs/mdbook/latest/mdbook/preprocess/trait.Preprocessor.html
 [pc]: https://crates.io/crates/pulldown-cmark
 [pctc]: https://crates.io/crates/pulldown-cmark-to-cmark
-[example]: https://github.com/rust-lang/mdBook/blob/master/examples/nop-preprocessor.rs
 [an example no-op preprocessor]: https://github.com/rust-lang/mdBook/blob/master/examples/nop-preprocessor.rs
 [`CmdPreprocessor::parse_input()`]: https://docs.rs/mdbook/latest/mdbook/preprocess/trait.Preprocessor.html#method.parse_input
 [`Book::for_each_mut()`]: https://docs.rs/mdbook/latest/mdbook/book/struct.Book.html#method.for_each_mut

guide/src/format/configuration/environment-variables.md

@@ -29,7 +29,7 @@ book's title without needing to touch your `book.toml`.
 > building the book with something like
 >
 > ```shell
-> $ export MDBOOK_BOOK="{'title': 'My Awesome Book', authors: ['Michael-F-Bryan']}"
+> $ export MDBOOK_BOOK='{"title": "My Awesome Book", "authors": ["Michael-F-Bryan"]}'
 > $ mdbook build
 > ```
 

guide/src/format/configuration/general.md

@@ -7,7 +7,7 @@ Here is an example of what a ***book.toml*** file might look like:
 ```toml
 [book]
 title = "Example book"
-author = "John Doe"
+authors = ["John Doe"]
 description = "The example book covers examples."
 
 [rust]
@@ -46,6 +46,9 @@ This is general information about your book.
   `src` directly under the root folder. But this is configurable with the `src`
   key in the configuration file.
 - **language:** The main language of the book, which is used as a language attribute `<html lang="en">` for example.
+  This is also used to derive the direction of text (RTL, LTR) within the book.
+- **text-direction**: The direction of text in the book: Left-to-right (LTR) or Right-to-left (RTL). Possible values: `ltr`, `rtl`.
+  When not specified, the text direction is derived from the book's `language` attribute.
 
 **book.toml**
 ```toml
@@ -55,6 +58,7 @@ authors = ["John Doe", "Jane Doe"]
 description = "The example book covers examples."
 src = "my-src"  # the source files will be found in `root/my-src` instead of `root/src`
 language = "en"
+text-direction = "ltr"
 ```
 
 ### Rust options
@@ -68,7 +72,7 @@ edition = "2015"   # the default edition for code blocks
 ```
 
 - **edition**: Rust edition to use by default for the code snippets. Default
-  is "2015". Individual code blocks can be controlled with the `edition2015`, 
+  is `"2015"`. Individual code blocks can be controlled with the `edition2015`,
   `edition2018` or `edition2021` annotations, such as:
 
   ~~~text
@@ -87,6 +91,7 @@ This controls the build process of your book.
 build-dir = "book"                # the directory where the output is placed
 create-missing = true             # whether or not to create missing pages
 use-default-preprocessors = true  # use the default preprocessors
+extra-watch-dirs = []             # directories to watch for triggering builds
 ```
 
 - **build-dir:** The directory to put the rendered book in. By default this is
@@ -96,7 +101,7 @@ use-default-preprocessors = true  # use the default preprocessors
   will be created when the book is built (i.e. `create-missing = true`). If this
   is `false` then the build process will instead exit with an error if any files
   do not exist.
-- **use-default-preprocessors:** Disable the default preprocessors of (`links` &
+- **use-default-preprocessors:** Disable the default preprocessors (of `links` &
   `index`) by setting this option to `false`.
 
   If you have the same, and/or other preprocessors declared via their table
@@ -108,3 +113,6 @@ use-default-preprocessors = true  # use the default preprocessors
     default preprocessors from running.
   - Adding `[preprocessor.links]`, for example, will ensure, regardless of
     `use-default-preprocessors` that `links` it will run.
+- **extra-watch-dirs**: A list of paths to directories that will be watched in
+  the `watch` and `serve` commands. Changes to files under these directories will
+  trigger rebuilds. Useful if your book depends on files outside its `src` directory.

guide/src/format/configuration/preprocessors.md

@@ -35,7 +35,7 @@ For example, if you have a preprocessor called `mdbook-example`, then you can in
 With this table, mdBook will execute the `mdbook-example` preprocessor.
 
 This table can include additional key-value pairs that are specific to the preprocessor.
-For example, if our example prepocessor needed some extra configuration options:
+For example, if our example preprocessor needed some extra configuration options:
 
 ```toml
 [preprocessor.example]

guide/src/format/configuration/renderers.md

@@ -4,9 +4,9 @@ Renderers (also called "backends") are responsible for creating the output of th
 
 The following backends are built-in:
 
-* [`html`](#html-renderer-options) — This renders the book to HTML.
+* [`html`](#html-renderer-options) --- This renders the book to HTML.
   This is enabled by default if no other `[output]` tables are defined in `book.toml`.
-* [`markdown`](#markdown-renderer) — This outputs the book as markdown after running the preprocessors.
+* [`markdown`](#markdown-renderer) --- This outputs the book as markdown after running the preprocessors.
   This is useful for debugging preprocessors.
 
 The community has developed several backends.
@@ -97,7 +97,7 @@ description = "The example book covers examples."
 theme = "my-theme"
 default-theme = "light"
 preferred-dark-theme = "navy"
-curly-quotes = true
+smart-punctuation = true
 mathjax-support = false
 copy-fonts = true
 additional-css = ["custom.css", "custom2.css"]
@@ -120,13 +120,18 @@ The following configuration options are available:
   'Change Theme' dropdown. Defaults to `light`.
 - **preferred-dark-theme:** The default dark theme. This theme will be used if
   the browser requests the dark version of the site via the
-  ['prefers-color-scheme'](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme)
+  [`prefers-color-scheme`](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme)
   CSS media query. Defaults to `navy`.
-- **curly-quotes:** Convert straight quotes to curly quotes, except for those
-  that occur in code blocks and code spans. Defaults to `false`.
+- **smart-punctuation:** Converts quotes to curly quotes, `...` to `…`, `--` to en-dash, and `---` to em-dash.
+  See [Smart Punctuation](../markdown.md#smart-punctuation).
+  Defaults to `false`.
+- **curly-quotes:** Deprecated alias for `smart-punctuation`.
 - **mathjax-support:** Adds support for [MathJax](../mathjax.md). Defaults to
   `false`.
-- **copy-fonts:** Copies fonts.css and respective font files to the output directory and use them in the default theme. Defaults to `true`.
+- **copy-fonts:** (**Deprecated**) If `true` (the default), mdBook uses its built-in fonts which are copied to the output directory.
+  If `false`, the built-in fonts will not be used.
+  This option is deprecated. If you want to define your own custom fonts,
+  create a `theme/fonts/fonts.css` file and store the fonts in the `theme/fonts/` directory.
 - **google-analytics:** This field has been deprecated and will be removed in a future release.
   Use the `theme/head.hbs` file to add the appropriate Google Analytics code instead.
 - **additional-css:** If you need to slightly change the appearance of your book
@@ -147,9 +152,9 @@ The following configuration options are available:
 - **edit-url-template:** Edit url template, when provided shows a
   "Suggest an edit" button (which looks like <i class="fa fa-edit"></i>) for directly jumping to editing the currently
   viewed page. For e.g. GitHub projects set this to
-  `https://github.com/<owner>/<repo>/edit/master/{path}` or for
+  `https://github.com/<owner>/<repo>/edit/<branch>/{path}` or for
   Bitbucket projects set it to
-  `https://bitbucket.org/<owner>/<repo>/src/master/{path}?mode=edit`
+  `https://bitbucket.org/<owner>/<repo>/src/<branch>/{path}?mode=edit`
   where {path} will be replaced with the full path of the file in the
   repository.
 - **input-404:** The name of the markdown file used for missing files.
@@ -157,11 +162,18 @@ The following configuration options are available:
   Defaults to `404.md`.
 - **site-url:** The url where the book will be hosted. This is required to ensure
   navigation links and script/css imports in the 404 file work correctly, even when accessing
-  urls in subdirectories. Defaults to `/`.
+  urls in subdirectories. Defaults to `/`. If `site-url` is set,
+  make sure to use document relative links for your assets, meaning they should not start with `/`.
 - **cname:** The DNS subdomain or apex domain at which your book will be hosted.
   This string will be written to a file named CNAME in the root of your site, as
   required by GitHub Pages (see [*Managing a custom domain for your GitHub Pages
   site*][custom domain]).
+- **hash-files:** Include a cryptographic "fingerprint" of the files' contents in static asset filenames,
+  so that if the contents of the file are changed, the name of the file will also change.
+  For example, `css/chrome.css` may become `css/chrome-9b8f428e.css`.
+  Chapter HTML files are not renamed.
+  Static CSS and JS files can reference each other using `{{ resource "filename" }}` directives.
+  Defaults to `false` (in a future release, this may change to `true`).
 
 [custom domain]: https://docs.github.com/en/github/working-with-github-pages/managing-a-custom-domain-for-your-github-pages-site
 
@@ -178,7 +190,7 @@ page-break = true # insert page-break after each chapter
 
 - **enable:** Enable print support. When `false`, all print support will not be
   rendered. Defaults to `true`.
-- **page-break** Insert page breaks between chapters. Defaults to `true`.
+- **page-break:** Insert page breaks between chapters. Defaults to `true`.
 
 ### `[output.html.fold]`
 
@@ -214,11 +226,25 @@ runnable = true          # displays a run button for rust code
 - **copyable:** Display the copy button on code snippets. Defaults to `true`.
 - **copy-js:** Copy JavaScript files for the editor to the output directory.
   Defaults to `true`.
-- **line-numbers** Display line numbers on editable sections of code. Requires both `editable` and `copy-js` to be `true`. Defaults to `false`.
-- **runnable** Displays a run button for rust code snippets. Changing this to `false` will disable the run in playground feature globally. Defaults to `true`.
+- **line-numbers:** Display line numbers on editable sections of code. Requires both `editable` and `copy-js` to be `true`. Defaults to `false`.
+- **runnable:** Displays a run button for rust code snippets. Changing this to `false` will disable the run in playground feature globally. Defaults to `true`.
 
 [Ace]: https://ace.c9.io/
 
+### `[output.html.code]`
+
+The `[output.html.code]` table provides options for controlling code blocks.
+
+```toml
+[output.html.code]
+# A prefix string per language (one or more chars).
+# Any line starting with whitespace+prefix is hidden.
+hidelines = { python = "~" }
+```
+
+- **hidelines:** A table that defines how [hidden code lines](../mdbook.md#hiding-code-lines) work for each language.
+  The key is the language and the value is a string that will cause code lines starting with that prefix to be hidden.
+
 ### `[output.html.search]`
 
 The `[output.html.search]` table provides options for controlling the built-in text [search].
@@ -261,6 +287,20 @@ copy-js = true           # include Javascript code for search
 - **copy-js:** Copy JavaScript files for the search implementation to the output
   directory. Defaults to `true`.
 
+#### `[output.html.search.chapter]`
+
+The [`output.html.search.chapter`] table provides the ability to modify search settings per chapter or directory. Each key is the path to the chapter source file or directory, and the value is a table of settings to apply to that path. This will merge recursively, with more specific paths taking precedence.
+
+```toml
+[output.html.search.chapter]
+# Disables search indexing for all chapters in the `appendix` directory.
+"appendix" = { enable = false }
+# Enables search indexing for just this one appendix chapter.
+"appendix/glossary.md" = { enable = true }
+```
+
+- **enable:** Enables or disables search indexing for the given chapters. Defaults to `true`. This does not override the overall `output.html.search.enable` setting; that must be `true` for any search functionality to be enabled. Be cautious when disabling indexing for chapters because that can potentially lead to user confusion when they search for terms and expect them to be found. This should only be used in exceptional circumstances where keeping the chapter in the index will cause issues with the quality of the search results.
+
 ### `[output.html.redirect]`
 
 The `[output.html.redirect]` table provides a way to add redirects.

guide/src/format/markdown.md

@@ -73,14 +73,14 @@ Linking to a URL or local file is easy:
 ```markdown
 Use [mdBook](https://github.com/rust-lang/mdBook). 
 
-Read about [mdBook](mdBook.md).
+Read about [mdBook](mdbook.md).
 
 A bare url: <https://www.rust-lang.org>.
 ```
 
 Use [mdBook](https://github.com/rust-lang/mdBook). 
 
-Read about [mdBook](mdBook.md).
+Read about [mdBook](mdbook.md).
 
 A bare url: <https://www.rust-lang.org>.
 
@@ -124,7 +124,7 @@ mdBook has several extensions beyond the standard CommonMark specification.
 ### Strikethrough
 
 Text may be rendered with a horizontal line through the center by wrapping the
-text with two tilde characters on each side:
+text with one or two tilde characters on each side:
 
 ```text
 An example of ~~strikethrough text~~.
@@ -214,9 +214,22 @@ characters:
 So, no need to manually enter those Unicode characters!
 
 This feature is disabled by default.
-To enable it, see the [`output.html.curly-quotes`] config option.
+To enable it, see the [`output.html.smart-punctuation`] config option.
 
 [strikethrough]: https://github.github.com/gfm/#strikethrough-extension-
 [tables]: https://github.github.com/gfm/#tables-extension-
 [task list extension]: https://github.github.com/gfm/#task-list-items-extension-
-[`output.html.curly-quotes`]: configuration/renderers.md#html-renderer-options
+[`output.html.smart-punctuation`]: configuration/renderers.md#html-renderer-options
+
+### Heading attributes
+
+Headings can have a custom HTML ID and classes. This lets you maintain the same ID even if you change the heading's text, it also lets you add multiple classes in the heading.
+
+Example:
+```md
+# Example heading { #first .class1 .class2 }
+```
+
+This makes the level 1 heading with the content `Example heading`, ID `first`, and classes `class1` and `class2`. Note that the attributes should be space-separated.
+
+More information can be found in the [heading attrs spec page](https://github.com/raphlinus/pulldown-cmark/blob/master/pulldown-cmark/specs/heading_attrs.txt).

guide/src/format/mdbook.md

@@ -2,11 +2,12 @@
 
 ## Hiding code lines
 
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#` [like you would with Rustdoc][rustdoc-hide].
-This currently only works with Rust language code blocks.
+There is a feature in mdBook that lets you hide code lines by prepending them with a specific prefix.
 
-[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/documentation-tests.html#hiding-portions-of-the-example
+For the Rust language, you can prefix lines with `# ` (`#` followed by a space) to hide them [like you would with Rustdoc][rustdoc-hide].
+This prefix can be escaped with `##` to prevent the hiding of a line that should begin with the literal string `# ` (see [Rustdoc's docs][rustdoc-hide] for more details)
+
+[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/write-documentation/documentation-tests.html#hiding-portions-of-the-example
 
 ```bash
 # fn main() {
@@ -28,7 +29,47 @@ Will render as
 # }
 ```
 
-The code block has an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+When you tap or hover the mouse over the code block, there will be an eyeball icon (<i class="fa fa-eye"></i>) which will toggle the visibility of the hidden lines.
+
+By default, this only works for code examples that are annotated with `rust`.
+However, you can define custom prefixes for other languages by adding a new line-hiding prefix in your `book.toml` with the language name and prefix character(s):
+
+```toml
+[output.html.code.hidelines]
+python = "~"
+```
+
+The prefix will hide any lines that begin with the given prefix. With the python prefix shown above, this:
+
+```bash
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+will render as
+
+```python
+~hidden()
+nothidden():
+~    hidden()
+    ~hidden()
+    nothidden()
+```
+
+This behavior can be overridden locally with a different prefix. This has the same effect as above:
+
+~~~markdown
+```python,hidelines=!!!
+!!!hidden()
+nothidden():
+!!!    hidden()
+    !!!hidden()
+    nothidden()
+```
+~~~
 
 ## Rust Playground
 
@@ -72,16 +113,16 @@ panic!("oops!");
 These are particularly important when using [`mdbook test`] to test Rust examples.
 These use the same attributes as [rustdoc attributes], with a few additions:
 
-* `editable` — Enables the [editor].
-* `noplayground` — Removes the play button, but will still be tested.
-* `mdbook-runnable` — Forces the play button to be displayed.
+* `editable` --- Enables the [editor].
+* `noplayground` --- Removes the play button, but will still be tested.
+* `mdbook-runnable` --- Forces the play button to be displayed.
   This is intended to be combined with the `ignore` attribute for examples that should not be tested, but you want to allow the reader to run.
-* `ignore` — Will not be tested and no play button is shown, but it is still highlighted as Rust syntax.
-* `should_panic` — When executed, it should produce a panic.
-* `no_run` — The code is compiled when tested, but it is not run.
+* `ignore` --- Will not be tested and no play button is shown, but it is still highlighted as Rust syntax.
+* `should_panic` --- When executed, it should produce a panic.
+* `no_run` --- The code is compiled when tested, but it is not run.
   The play button is also not shown.
-* `compile_fail` — The code should fail to compile.
-* `edition2015`, `edition2018`, `edition2021` — Forces the use of a specific Rust edition.
+* `compile_fail` --- The code should fail to compile.
+* `edition2015`, `edition2018`, `edition2021` --- Forces the use of a specific Rust edition.
   See [`rust.edition`] to set this globally.
 
 [`mdbook test`]: ../cli/test.md
@@ -274,3 +315,51 @@ contents (sidebar) by including a `\{{#title ...}}` near the top of the page.
 ```hbs
 \{{#title My Title}}
 ```
+
+## HTML classes provided by mdBook
+
+<img class="right" src="images/rust-logo-blk.svg" alt="The Rust logo">
+
+### `class="left"` and `"right"`
+
+These classes are provided by default, for inline HTML to float images.
+
+```html
+<img class="right" src="images/rust-logo-blk.svg" alt="The Rust logo">
+```
+
+### `class="hidden"`
+
+HTML tags with class `hidden` will not be shown.
+
+```html
+<div class="hidden">This will not be seen.</div>
+```
+
+<div class="hidden">This will not be seen.</div>
+
+### `class="warning"`
+
+To make a warning or similar note stand out, wrap it in a warning div.
+
+```html
+<div class="warning">
+
+This is a bad thing that you should pay attention to.
+
+Warning blocks should be used sparingly in documentation, to avoid "warning
+fatigue," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>
+```
+
+<div class="warning">
+
+This is a bad thing that you should pay attention to.
+
+Warning blocks should be used sparingly in documentation, to avoid "warning
+fatigue," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>

guide/src/format/summary.md

@@ -29,11 +29,12 @@ to be ignored at best, or may cause an error when attempting to build the book.
    - [First Chapter](relative/path/to/markdown2.md)
    ```
 
-1. ***Part Title*** - Headers can be used as a title for the following numbered
-   chapters. This can be used to logically separate different sections
-   of the book. The title is rendered as unclickable text.
-   Titles are optional, and the numbered chapters can be broken into as many
-   parts as desired.
+1. ***Part Title*** -
+   Level 1 headers can be used as a title for the following numbered chapters.
+   This can be used to logically separate different sections of the book.
+   The title is rendered as unclickable text.
+   Titles are optional, and the numbered chapters can be broken into as many parts as desired.
+   Part titles must be h1 headers (one `#`), other heading levels are ignored.
    ```markdown
    # My Part Title
 

guide/src/format/theme/README.md

@@ -1,6 +1,6 @@
 # Theme
 
-The default renderer uses a [handlebars](http://handlebarsjs.com/) template to
+The default renderer uses a [handlebars](https://handlebarsjs.com) template to
 render your markdown files and comes with a default theme included in the mdBook
 binary.
 
@@ -26,6 +26,8 @@ Here are the files you can override:
 - **_highlight.css_** is the theme used for the code highlighting.
 - **_favicon.svg_** and **_favicon.png_** the favicon that will be used. The SVG
   version is used by [newer browsers].
+- **fonts/fonts.css** contains the definition of which fonts to load.
+  Custom fonts can be included in the `fonts` directory.
 
 Generally, when you want to tweak the theme, you don't need to override all the
 files. If you only need changes in the stylesheet, there is no point in

guide/src/format/theme/editor.md

@@ -9,8 +9,8 @@ be added to the ***book.toml***:
 editable = true
 ```
 
-To make a specific block available for editing, the attribute `editable` needs
-to be added to it:
+After enabling editable code blocks, the `editable` attribute must be added to a
+code block to make it editable:
 
 ~~~markdown
 ```rust,editable

guide/src/format/theme/index-hbs.md

@@ -18,7 +18,7 @@ handlebars template you can access this information by using
 Here is a list of the properties that are exposed:
 
 - ***language*** Language of the book in the form `en`, as specified in `book.toml` (if not specified, defaults to `en`). To use in <code
-  class="language-html">\<html lang="{{ language }}"></code> for example.
+  class="language-html">\<html lang=\"{{ language }}\"></code> for example.
 - ***title*** Title used for the current page. This is identical to `{{ chapter_title }} - {{ book_title }}` unless `book_title` is not set in which case it just defaults to the `chapter_title`.
 - ***book_title*** Title of the book, as specified in `book.toml`
 - ***chapter_title*** Title of the current chapter, as listed in `SUMMARY.md`
@@ -79,7 +79,7 @@ var chapters = {{chapters}};
 
 ### 2. previous / next
 
-The previous and next helpers expose a `link` and `name` property to the
+The previous and next helpers expose a `link` and `title` property to the
 previous and next chapters.
 
 They are used like this
@@ -87,7 +87,7 @@ They are used like this
 ```handlebars
 {{#previous}}
     <a href="{{link}}" class="nav-chapters previous">
-        <i class="fa fa-angle-left"></i>
+        <i class="fa fa-angle-left"></i> {{title}}
     </a>
 {{/previous}}
 ```
@@ -99,3 +99,13 @@ Of course the inner html can be changed to your liking.
 
 *If you would like other properties or helpers exposed, please [create a new
 issue](https://github.com/rust-lang/mdBook/issues)*
+
+### 3. resource
+
+The path to a static file.
+It implicitly includes `path_to_root`,
+and accounts for files that are renamed with a hash in their filename.
+
+```handlebars
+<link rel="stylesheet" href="{{ resource "css/chrome.css" }}">
+```

guide/src/format/theme/syntax-highlighting.md

@@ -44,6 +44,8 @@ your own `highlight.js` file:
 - makefile
 - markdown
 - nginx
+- nim
+- nix
 - objectivec
 - perl
 - php
@@ -77,38 +79,6 @@ the `theme` folder of your book.
 
 Now your theme will be used instead of the default theme.
 
-## Hiding code lines
-
-There is a feature in mdBook that lets you hide code lines by prepending them
-with a `#`.
-
-
-```bash
-# fn main() {
-    let x = 5;
-    let y = 6;
-
-    println!("{}", x + y);
-# }
-```
-
-Will render as
-
-```rust
-# fn main() {
-    let x = 5;
-    let y = 7;
-
-    println!("{}", x + y);
-# }
-```
-
-**At the moment, this only works for code examples that are annotated with
-`rust`. Because it would collide with semantics of some programming languages.
-In the future, we want to make this configurable through the `book.toml` so that
-everyone can benefit from it.**
-
-
 ## Improve default theme
 
 If you think the default theme doesn't look quite right for a specific language,

guide/src/guide/installation.md

@@ -20,7 +20,7 @@ To make it easier to run, put the path to the binary into your `PATH`.
 
 To build the `mdbook` executable from source, you will first need to install Rust and Cargo.
 Follow the instructions on the [Rust installation page].
-mdBook currently requires at least Rust version 1.54.
+mdBook currently requires at least Rust version 1.81.
 
 Once you have installed Rust, the following command can be used to build and install mdBook:
 
@@ -30,6 +30,11 @@ cargo install mdbook
 
 This will automatically download mdBook from [crates.io], build it, and install it in Cargo's global binary directory (`~/.cargo/bin/` by default).
 
+You can run `cargo install mdbook` again whenever you want to update to a new version.
+That command will check if there is a newer version, and re-install mdBook if a newer version is found.
+
+To uninstall, run the command `cargo uninstall mdbook`.
+
 [Rust installation page]: https://www.rust-lang.org/tools/install
 [crates.io]: https://crates.io/
 
@@ -45,6 +50,8 @@ cargo install --git https://github.com/rust-lang/mdBook.git mdbook
 
 Again, make sure to add the Cargo bin directory to your `PATH`.
 
+## Modifying and contributing
+
 If you are interested in making modifications to mdBook itself, check out the [Contributing Guide] for more information.
 
 [Contributing Guide]: https://github.com/rust-lang/mdBook/blob/master/CONTRIBUTING.md

package.json

@@ -0,0 +1,10 @@
+{
+  "dependencies": {
+    "browser-ui-test": "0.19.0",
+    "eslint": "^8.57.1"
+  },
+  "scripts": {
+    "lint": "eslint src/front-end/*js src/front-end/**/*js",
+    "lint-fix": "eslint --fix src/front-end/*js src/front-end/**/*js"
+  }  
+}

src/book/book.rs

@@ -8,6 +8,8 @@ use super::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem};
 use crate::config::BuildConfig;
 use crate::errors::*;
 use crate::utils::bracket_escape;
+use log::debug;
+use serde::{Deserialize, Serialize};
 
 /// Load a book into memory from its `src/` directory.
 pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book> {
@@ -16,11 +18,11 @@ pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book>
 
     let mut summary_content = String::new();
     File::open(&summary_md)
-        .with_context(|| format!("Couldn't open SUMMARY.md in {:?} directory", src_dir))?
+        .with_context(|| format!("Couldn't open SUMMARY.md in {src_dir:?} directory"))?
         .read_to_string(&mut summary_content)?;
 
     let summary = parse_summary(&summary_content)
-        .with_context(|| format!("Summary parsing failed for file={:?}", summary_md))?;
+        .with_context(|| format!("Summary parsing failed for file={summary_md:?}"))?;
 
     if cfg.create_missing {
         create_missing(src_dir, &summary).with_context(|| "Unable to create missing chapters")?;
@@ -37,9 +39,7 @@ fn create_missing(src_dir: &Path, summary: &Summary) -> Result<()> {
         .chain(summary.suffix_chapters.iter())
         .collect();
 
-    while !items.is_empty() {
-        let next = items.pop().expect("already checked");
-
+    while let Some(next) = items.pop() {
         if let SummaryItem::Link(ref link) = *next {
             if let Some(ref location) = link.location {
                 let filename = src_dir.join(location);
@@ -160,8 +160,21 @@ pub struct Chapter {
     /// Nested items.
     pub sub_items: Vec<BookItem>,
     /// The chapter's location, relative to the `SUMMARY.md` file.
+    ///
+    /// **Note**: After the index preprocessor runs, any README files will be
+    /// modified to be `index.md`. If you need access to the actual filename
+    /// on disk, use [`Chapter::source_path`] instead.
+    ///
+    /// This is `None` for a draft chapter.
     pub path: Option<PathBuf>,
     /// The chapter's source file, relative to the `SUMMARY.md` file.
+    ///
+    /// **Note**: Beware that README files will internally be treated as
+    /// `index.md` via the [`Chapter::path`] field. The `source_path` field
+    /// exists if you need access to the true file path.
+    ///
+    /// This is `None` for a draft chapter, or a synthetically generated
+    /// chapter that has no file on disk.
     pub source_path: Option<PathBuf>,
     /// An ordered list of the names of each chapter above this one in the hierarchy.
     pub parent_names: Vec<String>,
@@ -275,7 +288,7 @@ fn load_chapter<P: AsRef<Path>>(
         }
 
         let stripped = location
-            .strip_prefix(&src_dir)
+            .strip_prefix(src_dir)
             .expect("Chapters are always inside a book");
 
         Chapter::new(&link.name, content, stripped, parent_names.clone())
@@ -315,7 +328,7 @@ impl<'a> Iterator for BookItems<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         let item = self.items.pop_front();
 
-        if let Some(&BookItem::Chapter(ref ch)) = item {
+        if let Some(BookItem::Chapter(ch)) = item {
             // if we wanted a breadth-first iterator we'd `extend()` here
             for sub_item in ch.sub_items.iter().rev() {
                 self.items.push_front(sub_item);
@@ -329,7 +342,7 @@ impl<'a> Iterator for BookItems<'a> {
 impl Display for Chapter {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         if let Some(ref section_number) = self.number {
-            write!(f, "{} ", section_number)?;
+            write!(f, "{section_number} ")?;
         }
 
         write!(f, "{}", self.name)
@@ -339,7 +352,6 @@ impl Display for Chapter {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::io::Write;
     use tempfile::{Builder as TempFileBuilder, TempDir};
 
     const DUMMY_SRC: &str = "
@@ -635,4 +647,19 @@ And here is some \
         let got = load_book_from_disk(&summary, temp.path());
         assert!(got.is_err());
     }
+
+    #[test]
+    fn cant_open_summary_md() {
+        let cfg = BuildConfig::default();
+        let temp_dir = TempFileBuilder::new().prefix("book").tempdir().unwrap();
+
+        let got = load_book(&temp_dir, &cfg);
+        assert!(got.is_err());
+        let error_message = got.err().unwrap().to_string();
+        let expected = format!(
+            r#"Couldn't open SUMMARY.md in {:?} directory"#,
+            temp_dir.path()
+        );
+        assert_eq!(error_message, expected);
+    }
 }

src/book/init.rs

@@ -6,6 +6,8 @@ use super::MDBook;
 use crate::config::Config;
 use crate::errors::*;
 use crate::theme;
+use crate::utils::fs::write_file;
+use log::{debug, error, info, trace};
 
 /// A helper for setting up a new book and its directory structure.
 #[derive(Debug, Clone, PartialEq)]
@@ -157,6 +159,19 @@ impl BookBuilder {
         let mut highlight_js = File::create(themedir.join("highlight.js"))?;
         highlight_js.write_all(theme::HIGHLIGHT_JS)?;
 
+        write_file(&themedir.join("fonts"), "fonts.css", theme::fonts::CSS)?;
+        for (file_name, contents) in theme::fonts::LICENSES {
+            write_file(&themedir, file_name, contents)?;
+        }
+        for (file_name, contents) in theme::fonts::OPEN_SANS.iter() {
+            write_file(&themedir, file_name, contents)?;
+        }
+        write_file(
+            &themedir,
+            theme::fonts::SOURCE_CODE_PRO.0,
+            theme::fonts::SOURCE_CODE_PRO.1,
+        )?;
+
         Ok(())
     }
 
@@ -183,8 +198,7 @@ impl BookBuilder {
             writeln!(f, "- [Chapter 1](./chapter_1.md)")?;
 
             let chapter_1 = src_dir.join("chapter_1.md");
-            let mut f =
-                File::create(&chapter_1).with_context(|| "Unable to create chapter_1.md")?;
+            let mut f = File::create(chapter_1).with_context(|| "Unable to create chapter_1.md")?;
             writeln!(f, "# Chapter 1")?;
         } else {
             trace!("Existing summary found, no need to create stub files.");
@@ -197,10 +211,10 @@ impl BookBuilder {
         fs::create_dir_all(&self.root)?;
 
         let src = self.root.join(&self.config.book.src);
-        fs::create_dir_all(&src)?;
+        fs::create_dir_all(src)?;
 
         let build = self.root.join(&self.config.build.build_dir);
-        fs::create_dir_all(&build)?;
+        fs::create_dir_all(build)?;
 
         Ok(())
     }

src/book/mod.rs

@@ -5,7 +5,6 @@
 //!
 //! [1]: ../index.html
 
-#[allow(clippy::module_inception)]
 mod book;
 mod init;
 mod summary;
@@ -14,10 +13,11 @@ pub use self::book::{load_book, Book, BookItem, BookItems, Chapter};
 pub use self::init::BookBuilder;
 pub use self::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem};
 
-use std::io::Write;
-use std::path::PathBuf;
+use log::{debug, error, info, log_enabled, trace, warn};
+use std::ffi::OsString;
+use std::io::{IsTerminal, Write};
+use std::path::{Path, PathBuf};
 use std::process::Command;
-use std::string::ToString;
 use tempfile::Builder as TempFileBuilder;
 use toml::Value;
 use topological_sort::TopologicalSort;
@@ -70,22 +70,28 @@ impl MDBook {
 
         config.update_from_env();
 
-        if config
-            .html_config()
-            .map_or(false, |html| html.google_analytics.is_some())
-        {
-            warn!(
-                "The output.html.google-analytics field has been deprecated; \
-                 it will be removed in a future release.\n\
-                 Consider placing the appropriate site tag code into the \
-                 theme/head.hbs file instead.\n\
-                 The tracking code may be found in the Google Analytics Admin page.\n\
-               "
-            );
+        if let Some(html_config) = config.html_config() {
+            if html_config.google_analytics.is_some() {
+                warn!(
+                    "The output.html.google-analytics field has been deprecated; \
+                     it will be removed in a future release.\n\
+                     Consider placing the appropriate site tag code into the \
+                     theme/head.hbs file instead.\n\
+                     The tracking code may be found in the Google Analytics Admin page.\n\
+                   "
+                );
+            }
+            if html_config.curly_quotes {
+                warn!(
+                    "The output.html.curly-quotes field has been renamed to \
+                     output.html.smart-punctuation.\n\
+                     Use the new name in book.toml to remove this warning."
+                );
+            }
         }
 
         if log_enabled!(log::Level::Trace) {
-            for line in format!("Config: {:#?}", config).lines() {
+            for line in format!("Config: {config:#?}").lines() {
                 trace!("{}", line);
             }
         }
@@ -98,7 +104,7 @@ impl MDBook {
         let root = book_root.into();
 
         let src_dir = root.join(&config.book.src);
-        let book = book::load_book(&src_dir, &config.build)?;
+        let book = book::load_book(src_dir, &config.build)?;
 
         let renderers = determine_renderers(&config);
         let preprocessors = determine_preprocessors(&config)?;
@@ -121,7 +127,7 @@ impl MDBook {
         let root = book_root.into();
 
         let src_dir = root.join(&config.book.src);
-        let book = book::load_book_from_disk(&summary, &src_dir)?;
+        let book = book::load_book_from_disk(&summary, src_dir)?;
 
         let renderers = determine_renderers(&config);
         let preprocessors = determine_preprocessors(&config)?;
@@ -195,21 +201,26 @@ impl MDBook {
         Ok(())
     }
 
-    /// Run the entire build process for a particular [`Renderer`].
-    pub fn execute_build_process(&self, renderer: &dyn Renderer) -> Result<()> {
-        let mut preprocessed_book = self.book.clone();
+    /// Run preprocessors and return the final book.
+    pub fn preprocess_book(&self, renderer: &dyn Renderer) -> Result<(Book, PreprocessorContext)> {
         let preprocess_ctx = PreprocessorContext::new(
             self.root.clone(),
             self.config.clone(),
             renderer.name().to_string(),
         );
-
+        let mut preprocessed_book = self.book.clone();
         for preprocessor in &self.preprocessors {
             if preprocessor_should_run(&**preprocessor, renderer, &self.config) {
                 debug!("Running the {} preprocessor.", preprocessor.name());
                 preprocessed_book = preprocessor.run(&preprocess_ctx, preprocessed_book)?;
             }
         }
+        Ok((preprocessed_book, preprocess_ctx))
+    }
+
+    /// Run the entire build process for a particular [`Renderer`].
+    pub fn execute_build_process(&self, renderer: &dyn Renderer) -> Result<()> {
+        let (preprocessed_book, preprocess_ctx) = self.preprocess_book(renderer)?;
 
         let name = renderer.name();
         let build_dir = self.build_dir_for(name);
@@ -246,22 +257,52 @@ impl MDBook {
 
     /// Run `rustdoc` tests on the book, linking against the provided libraries.
     pub fn test(&mut self, library_paths: Vec<&str>) -> Result<()> {
-        let library_args: Vec<&str> = (0..library_paths.len())
-            .map(|_| "-L")
-            .zip(library_paths.into_iter())
-            .flat_map(|x| vec![x.0, x.1])
+        // test_chapter with chapter:None will run all tests.
+        self.test_chapter(library_paths, None)
+    }
+
+    /// Run `rustdoc` tests on a specific chapter of the book, linking against the provided libraries.
+    /// If `chapter` is `None`, all tests will be run.
+    pub fn test_chapter(&mut self, library_paths: Vec<&str>, chapter: Option<&str>) -> Result<()> {
+        let cwd = std::env::current_dir()?;
+        let library_args: Vec<OsString> = library_paths
+            .into_iter()
+            .flat_map(|path| {
+                let path = Path::new(path);
+                let path = if path.is_relative() {
+                    cwd.join(path).into_os_string()
+                } else {
+                    path.to_path_buf().into_os_string()
+                };
+                [OsString::from("-L"), path]
+            })
             .collect();
 
         let temp_dir = TempFileBuilder::new().prefix("mdbook-").tempdir()?;
 
-        // FIXME: Is "test" the proper renderer name to use here?
-        let preprocess_context =
-            PreprocessorContext::new(self.root.clone(), self.config.clone(), "test".to_string());
+        let mut chapter_found = false;
 
-        let book = LinkPreprocessor::new().run(&preprocess_context, self.book.clone())?;
-        // Index Preprocessor is disabled so that chapter paths continue to point to the
-        // actual markdown files.
+        struct TestRenderer;
+        impl Renderer for TestRenderer {
+            // FIXME: Is "test" the proper renderer name to use here?
+            fn name(&self) -> &str {
+                "test"
+            }
 
+            fn render(&self, _: &RenderContext) -> Result<()> {
+                Ok(())
+            }
+        }
+
+        // Index Preprocessor is disabled so that chapter paths
+        // continue to point to the actual markdown files.
+        self.preprocessors = determine_preprocessors(&self.config)?
+            .into_iter()
+            .filter(|pre| pre.name() != IndexPreprocessor::NAME)
+            .collect();
+        let (book, _) = self.preprocess_book(&TestRenderer)?;
+
+        let color_output = std::io::stderr().is_terminal();
         let mut failed = false;
         for item in book.iter() {
             if let BookItem::Chapter(ref ch) = *item {
@@ -270,32 +311,53 @@ impl MDBook {
                     _ => continue,
                 };
 
-                let path = self.source_dir().join(&chapter_path);
-                info!("Testing file: {:?}", path);
+                if let Some(chapter) = chapter {
+                    if ch.name != chapter && chapter_path.to_str() != Some(chapter) {
+                        if chapter == "?" {
+                            info!("Skipping chapter '{}'...", ch.name);
+                        }
+                        continue;
+                    }
+                }
+                chapter_found = true;
+                info!("Testing chapter '{}': {:?}", ch.name, chapter_path);
 
                 // write preprocessed file to tempdir
-                let path = temp_dir.path().join(&chapter_path);
+                let path = temp_dir.path().join(chapter_path);
                 let mut tmpf = utils::fs::create_file(&path)?;
                 tmpf.write_all(ch.content.as_bytes())?;
 
                 let mut cmd = Command::new("rustdoc");
-                cmd.arg(&path).arg("--test").args(&library_args);
+                cmd.current_dir(temp_dir.path())
+                    .arg(chapter_path)
+                    .arg("--test")
+                    .args(&library_args);
 
                 if let Some(edition) = self.config.rust.edition {
                     match edition {
                         RustEdition::E2015 => {
-                            cmd.args(&["--edition", "2015"]);
+                            cmd.args(["--edition", "2015"]);
                         }
                         RustEdition::E2018 => {
-                            cmd.args(&["--edition", "2018"]);
+                            cmd.args(["--edition", "2018"]);
                         }
                         RustEdition::E2021 => {
-                            cmd.args(&["--edition", "2021"]);
+                            cmd.args(["--edition", "2021"]);
+                        }
+                        RustEdition::E2024 => {
+                            cmd.args(["--edition", "2024"]);
                         }
                     }
                 }
 
-                let output = cmd.output()?;
+                if color_output {
+                    cmd.args(["--color", "always"]);
+                }
+
+                debug!("running {:?}", cmd);
+                let output = cmd
+                    .output()
+                    .with_context(|| "failed to execute `rustdoc`")?;
 
                 if !output.status.success() {
                     failed = true;
@@ -311,6 +373,11 @@ impl MDBook {
         if failed {
             bail!("One or more tests failed");
         }
+        if let Some(chapter) = chapter {
+            if !chapter_found {
+                bail!("Chapter not found: {}", chapter);
+            }
+        }
         Ok(())
     }
 
@@ -386,7 +453,7 @@ fn determine_renderers(config: &Config) -> Vec<Box<dyn Renderer>> {
     renderers
 }
 
-const DEFAULT_PREPROCESSORS: &[&'static str] = &["links", "index"];
+const DEFAULT_PREPROCESSORS: &[&str] = &["links", "index"];
 
 fn is_default_preprocessor(pre: &dyn Preprocessor) -> bool {
     let name = pre.name();
@@ -417,15 +484,13 @@ fn determine_preprocessors(config: &Config) -> Result<Vec<Box<dyn Preprocessor>>
             if let Some(before) = table.get("before") {
                 let before = before.as_array().ok_or_else(|| {
                     Error::msg(format!(
-                        "Expected preprocessor.{}.before to be an array",
-                        name
+                        "Expected preprocessor.{name}.before to be an array"
                     ))
                 })?;
                 for after in before {
                     let after = after.as_str().ok_or_else(|| {
                         Error::msg(format!(
-                            "Expected preprocessor.{}.before to contain strings",
-                            name
+                            "Expected preprocessor.{name}.before to contain strings"
                         ))
                     })?;
 
@@ -444,16 +509,12 @@ fn determine_preprocessors(config: &Config) -> Result<Vec<Box<dyn Preprocessor>>
 
             if let Some(after) = table.get("after") {
                 let after = after.as_array().ok_or_else(|| {
-                    Error::msg(format!(
-                        "Expected preprocessor.{}.after to be an array",
-                        name
-                    ))
+                    Error::msg(format!("Expected preprocessor.{name}.after to be an array"))
                 })?;
                 for before in after {
                     let before = before.as_str().ok_or_else(|| {
                         Error::msg(format!(
-                            "Expected preprocessor.{}.after to contain strings",
-                            name
+                            "Expected preprocessor.{name}.after to contain strings"
                         ))
                     })?;
 
@@ -515,7 +576,7 @@ fn get_custom_preprocessor_cmd(key: &str, table: &Value) -> String {
         .get("command")
         .and_then(Value::as_str)
         .map(ToString::to_string)
-        .unwrap_or_else(|| format!("mdbook-{}", key))
+        .unwrap_or_else(|| format!("mdbook-{key}"))
 }
 
 fn interpret_custom_renderer(key: &str, table: &Value) -> Box<CmdRenderer> {
@@ -526,7 +587,7 @@ fn interpret_custom_renderer(key: &str, table: &Value) -> Box<CmdRenderer> {
         .and_then(Value::as_str)
         .map(ToString::to_string);
 
-    let command = table_dot_command.unwrap_or_else(|| format!("mdbook-{}", key));
+    let command = table_dot_command.unwrap_or_else(|| format!("mdbook-{key}"));
 
     Box::new(CmdRenderer::new(key.to_string(), command))
 }
@@ -564,7 +625,7 @@ fn preprocessor_should_run(
 mod tests {
     use super::*;
     use std::str::FromStr;
-    use toml::value::{Table, Value};
+    use toml::value::Table;
 
     #[test]
     fn config_defaults_to_html_renderer_if_empty() {
@@ -720,7 +781,7 @@ mod tests {
                 for preprocessor in &preprocessors {
                     eprintln!("  {}", preprocessor.name());
                 }
-                panic!("{} should come before {}", before, after);
+                panic!("{before} should come before {after}");
             }
         };
 
@@ -756,10 +817,9 @@ mod tests {
 
         let preprocessors = determine_preprocessors(&cfg).unwrap();
 
-        assert!(preprocessors
+        assert!(!preprocessors
             .iter()
-            .find(|preprocessor| preprocessor.name() == "random")
-            .is_none());
+            .any(|preprocessor| preprocessor.name() == "random"));
     }
 
     #[test]
@@ -776,10 +836,9 @@ mod tests {
 
         let preprocessors = determine_preprocessors(&cfg).unwrap();
 
-        assert!(preprocessors
+        assert!(!preprocessors
             .iter()
-            .find(|preprocessor| preprocessor.name() == "links")
-            .is_none());
+            .any(|preprocessor| preprocessor.name() == "links"));
     }
 
     #[test]
@@ -800,7 +859,7 @@ mod tests {
             .and_then(Value::as_str)
             .unwrap();
         assert_eq!(html, "html");
-        let html_renderer = HtmlHandlebars::default();
+        let html_renderer = HtmlHandlebars;
         let pre = LinkPreprocessor::new();
 
         let should_run = preprocessor_should_run(&pre, &html_renderer, &cfg);

src/book/summary.rs

@@ -1,8 +1,10 @@
 use crate::errors::*;
-use memchr::{self, Memchr};
-use pulldown_cmark::{self, Event, HeadingLevel, Tag};
+use log::{debug, trace, warn};
+use memchr::Memchr;
+use pulldown_cmark::{DefaultBrokenLinkCallback, Event, HeadingLevel, Tag, TagEnd};
+use serde::{Deserialize, Serialize};
+use std::collections::HashSet;
 use std::fmt::{self, Display, Formatter};
-use std::iter::FromIterator;
 use std::ops::{Deref, DerefMut};
 use std::path::{Path, PathBuf};
 
@@ -161,7 +163,7 @@ impl From<Link> for SummaryItem {
 /// > match the following regex: "[^<>\n[]]+".
 struct SummaryParser<'a> {
     src: &'a str,
-    stream: pulldown_cmark::OffsetIter<'a, 'a>,
+    stream: pulldown_cmark::OffsetIter<'a, DefaultBrokenLinkCallback>,
     offset: usize,
 
     /// We can't actually put an event back into the `OffsetIter` stream, so instead we store it
@@ -208,7 +210,7 @@ macro_rules! collect_events {
 }
 
 impl<'a> SummaryParser<'a> {
-    fn new(text: &str) -> SummaryParser<'_> {
+    fn new(text: &'a str) -> SummaryParser<'a> {
         let pulldown_parser = pulldown_cmark::Parser::new(text).into_offset_iter();
 
         SummaryParser {
@@ -244,6 +246,11 @@ impl<'a> SummaryParser<'a> {
             .parse_affix(false)
             .with_context(|| "There was an error parsing the suffix chapters")?;
 
+        let mut files = HashSet::new();
+        for part in [&prefix_chapters, &numbered_chapters, &suffix_chapters] {
+            Self::check_for_duplicates(&part, &mut files)?;
+        }
+
         Ok(Summary {
             title,
             prefix_chapters,
@@ -252,6 +259,28 @@ impl<'a> SummaryParser<'a> {
         })
     }
 
+    /// Recursively check for duplicate files in the summary items.
+    fn check_for_duplicates<'b>(
+        items: &'b [SummaryItem],
+        files: &mut HashSet<&'b PathBuf>,
+    ) -> Result<()> {
+        for item in items {
+            if let SummaryItem::Link(link) = item {
+                if let Some(location) = &link.location {
+                    if !files.insert(location) {
+                        bail!(anyhow::anyhow!(
+                            "Duplicate file in SUMMARY.md: {:?}",
+                            location
+                        ));
+                    }
+                }
+                // Recursively check nested items
+                Self::check_for_duplicates(&link.nested_items, files)?;
+            }
+        }
+        Ok(())
+    }
+
     /// Parse the affix chapters.
     fn parse_affix(&mut self, is_prefix: bool) -> Result<Vec<SummaryItem>> {
         let mut items = Vec::new();
@@ -263,7 +292,12 @@ impl<'a> SummaryParser<'a> {
         loop {
             match self.next_event() {
                 Some(ev @ Event::Start(Tag::List(..)))
-                | Some(ev @ Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                | Some(
+                    ev @ Event::Start(Tag::Heading {
+                        level: HeadingLevel::H1,
+                        ..
+                    }),
+                ) => {
                     if is_prefix {
                         // we've finished prefix chapters and are at the start
                         // of the numbered section.
@@ -273,8 +307,8 @@ impl<'a> SummaryParser<'a> {
                         bail!(self.parse_error("Suffix chapters cannot be followed by a list"));
                     }
                 }
-                Some(Event::Start(Tag::Link(_type, href, _title))) => {
-                    let link = self.parse_link(href.to_string());
+                Some(Event::Start(Tag::Link { dest_url, .. })) => {
+                    let link = self.parse_link(dest_url.to_string());
                     items.push(SummaryItem::Link(link));
                 }
                 Some(Event::Rule) => items.push(SummaryItem::Separator),
@@ -302,10 +336,13 @@ impl<'a> SummaryParser<'a> {
                     break;
                 }
 
-                Some(Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                Some(Event::Start(Tag::Heading {
+                    level: HeadingLevel::H1,
+                    ..
+                })) => {
                     debug!("Found a h1 in the SUMMARY");
 
-                    let tags = collect_events!(self.stream, end Tag::Heading(HeadingLevel::H1, ..));
+                    let tags = collect_events!(self.stream, end TagEnd::Heading(HeadingLevel::H1));
                     Some(stringify_events(tags))
                 }
 
@@ -334,7 +371,7 @@ impl<'a> SummaryParser<'a> {
     /// Finishes parsing a link once the `Event::Start(Tag::Link(..))` has been opened.
     fn parse_link(&mut self, href: String) -> Link {
         let href = href.replace("%20", " ");
-        let link_content = collect_events!(self.stream, end Tag::Link(..));
+        let link_content = collect_events!(self.stream, end TagEnd::Link);
         let name = stringify_events(link_content);
 
         let path = if href.is_empty() {
@@ -375,7 +412,12 @@ impl<'a> SummaryParser<'a> {
                 }
                 // The expectation is that pulldown cmark will terminate a paragraph before a new
                 // heading, so we can always count on this to return without skipping headings.
-                Some(ev @ Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                Some(
+                    ev @ Event::Start(Tag::Heading {
+                        level: HeadingLevel::H1,
+                        ..
+                    }),
+                ) => {
                     // we're starting a new part
                     self.back(ev);
                     break;
@@ -396,7 +438,7 @@ impl<'a> SummaryParser<'a> {
 
                     // Skip over the contents of this tag
                     while let Some(event) = self.next_event() {
-                        if event == Event::End(other_tag.clone()) {
+                        if event == Event::End(other_tag.clone().into()) {
                             break;
                         }
                     }
@@ -452,7 +494,7 @@ impl<'a> SummaryParser<'a> {
                     items.push(item);
                 }
                 Some(Event::Start(Tag::List(..))) => {
-                    // Skip this tag after comment bacause it is not nested.
+                    // Skip this tag after comment because it is not nested.
                     if items.is_empty() {
                         continue;
                     }
@@ -467,7 +509,7 @@ impl<'a> SummaryParser<'a> {
 
                     last_item.nested_items = sub_items;
                 }
-                Some(Event::End(Tag::List(..))) => break,
+                Some(Event::End(TagEnd::List(..))) => break,
                 Some(_) => {}
                 None => break,
             }
@@ -484,8 +526,8 @@ impl<'a> SummaryParser<'a> {
         loop {
             match self.next_event() {
                 Some(Event::Start(Tag::Paragraph)) => continue,
-                Some(Event::Start(Tag::Link(_type, href, _title))) => {
-                    let mut link = self.parse_link(href.to_string());
+                Some(Event::Start(Tag::Link { dest_url, .. })) => {
+                    let mut link = self.parse_link(dest_url.to_string());
 
                     let mut number = parent.clone();
                     number.0.push(num_existing_items as u32 + 1);
@@ -527,14 +569,18 @@ impl<'a> SummaryParser<'a> {
     fn parse_title(&mut self) -> Option<String> {
         loop {
             match self.next_event() {
-                Some(Event::Start(Tag::Heading(HeadingLevel::H1, ..))) => {
+                Some(Event::Start(Tag::Heading {
+                    level: HeadingLevel::H1,
+                    ..
+                })) => {
                     debug!("Found a h1 in the SUMMARY");
 
-                    let tags = collect_events!(self.stream, end Tag::Heading(HeadingLevel::H1, ..));
+                    let tags = collect_events!(self.stream, end TagEnd::Heading(HeadingLevel::H1));
                     return Some(stringify_events(tags));
                 }
                 // Skip a HTML element such as a comment line.
-                Some(Event::Html(_)) => {}
+                Some(Event::Html(_) | Event::InlineHtml(_))
+                | Some(Event::Start(Tag::HtmlBlock) | Event::End(TagEnd::HtmlBlock)) => {}
                 // Otherwise, no title.
                 Some(ev) => {
                     self.back(ev);
@@ -565,11 +611,13 @@ fn get_last_link(links: &mut [SummaryItem]) -> Result<(usize, &mut Link)> {
         .iter_mut()
         .enumerate()
         .filter_map(|(i, item)| item.maybe_link_mut().map(|l| (i, l)))
-        .rev()
-        .next()
-        .ok_or_else(||
-            anyhow::anyhow!("Unable to get last link because the list of SummaryItems doesn't contain any Links")
+        .next_back()
+        .ok_or_else(|| {
+            anyhow::anyhow!(
+                "Unable to get last link because the list of SummaryItems \
+                 doesn't contain any Links"
             )
+        })
 }
 
 /// Removes the styling from a list of Markdown events and returns just the
@@ -596,7 +644,7 @@ impl Display for SectionNumber {
             write!(f, "0")
         } else {
             for item in &self.0 {
-                write!(f, "{}.", item)?;
+                write!(f, "{item}.")?;
             }
             Ok(())
         }
@@ -727,6 +775,20 @@ mod tests {
         let got = parser.parse_affix(false);
 
         assert!(got.is_err());
+        let error_message = got.err().unwrap().to_string();
+        assert_eq!(error_message, "failed to parse SUMMARY.md line 2, column 1: Suffix chapters cannot be followed by a list");
+    }
+
+    #[test]
+    fn expected_a_start_of_a_link() {
+        let src = "- Title\n";
+        let mut parser = SummaryParser::new(src);
+
+        let got = parser.parse_affix(false);
+
+        assert!(got.is_err());
+        let error_message = got.err().unwrap().to_string();
+        assert_eq!(error_message, "failed to parse SUMMARY.md line 1, column 0: Suffix chapters cannot be followed by a list");
     }
 
     #[test]
@@ -742,8 +804,8 @@ mod tests {
         let _ = parser.stream.next(); // Discard opening paragraph
 
         let href = match parser.stream.next() {
-            Some((Event::Start(Tag::Link(_type, href, _title)), _range)) => href.to_string(),
-            other => panic!("Unreachable, {:?}", other),
+            Some((Event::Start(Tag::Link { dest_url, .. }), _range)) => dest_url.to_string(),
+            other => panic!("Unreachable, {other:?}"),
         };
 
         let got = parser.parse_link(href);
@@ -1093,4 +1155,83 @@ mod tests {
         let got = parser.parse_affix(false).unwrap();
         assert_eq!(got, should_be);
     }
+
+    #[test]
+    fn duplicate_entries_1() {
+        let src = r#"
+# Summary
+- [A](./a.md)
+- [A](./a.md)
+"#;
+
+        let res = parse_summary(src);
+        assert!(res.is_err());
+        let error_message = res.err().unwrap().to_string();
+        assert_eq!(error_message, r#"Duplicate file in SUMMARY.md: "./a.md""#);
+    }
+
+    #[test]
+    fn duplicate_entries_2() {
+        let src = r#"
+# Summary
+- [A](./a.md)
+  - [A](./a.md)
+"#;
+
+        let res = parse_summary(src);
+        assert!(res.is_err());
+        let error_message = res.err().unwrap().to_string();
+        assert_eq!(error_message, r#"Duplicate file in SUMMARY.md: "./a.md""#);
+    }
+    #[test]
+    fn duplicate_entries_3() {
+        let src = r#"
+# Summary
+- [A](./a.md)
+- [B](./b.md)
+  - [A](./a.md)
+"#;
+
+        let res = parse_summary(src);
+        assert!(res.is_err());
+        let error_message = res.err().unwrap().to_string();
+        assert_eq!(error_message, r#"Duplicate file in SUMMARY.md: "./a.md""#);
+    }
+
+    #[test]
+    fn duplicate_entries_4() {
+        let src = r#"
+# Summary
+[A](./a.md)
+- [B](./b.md)
+- [A](./a.md)
+"#;
+
+        let res = parse_summary(src);
+        assert!(res.is_err());
+        let error_message = res.err().unwrap().to_string();
+        assert_eq!(error_message, r#"Duplicate file in SUMMARY.md: "./a.md""#);
+    }
+
+    #[test]
+    fn duplicate_entries_5() {
+        let src = r#"
+# Summary
+[A](./a.md)
+
+# hi
+- [B](./b.md)
+
+# bye
+
+---
+
+[A](./a.md)
+"#;
+
+        let res = parse_summary(src);
+        assert!(res.is_err());
+        let error_message = res.err().unwrap().to_string();
+        assert_eq!(error_message, r#"Duplicate file in SUMMARY.md: "./a.md""#);
+    }
 }

src/cmd/build.rs

@@ -1,44 +1,37 @@
+use super::command_prelude::*;
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
 use mdbook::errors::Result;
 use mdbook::MDBook;
+use std::path::PathBuf;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("build")
+pub fn make_subcommand() -> Command {
+    Command::new("build")
         .about("Builds a book from its markdown files")
-        .arg(
-            Arg::new("dest-dir")
-                .short('d')
-                .long("dest-dir")
-                .value_name("dest-dir")
-                .help(
-                    "Output directory for the book{n}\
-                    Relative paths are interpreted relative to the book's root directory.{n}\
-                    If omitted, mdBook uses build.build-dir from book.toml or defaults to `./book`.",
-                ),
-        )
-        .arg(arg!([dir]
-            "Root directory for the book{n}\
-            (Defaults to the Current Directory when omitted)"
-        ))
-        .arg(arg!(-o --open "Opens the compiled book in a web browser"))
+        .arg_dest_dir()
+        .arg_root_dir()
+        .arg_open()
 }
 
 // Build command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
-    if let Some(dest_dir) = args.value_of("dest-dir") {
+    if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
         book.config.build.build_dir = dest_dir.into();
     }
 
     book.build()?;
 
-    if args.is_present("open") {
+    if args.get_flag("open") {
         // FIXME: What's the right behaviour if we don't use the HTML renderer?
-        open(book.build_dir_for("html").join("index.html"));
+        let path = book.build_dir_for("html").join("index.html");
+        if !path.exists() {
+            error!("No chapter available to open");
+            std::process::exit(1)
+        }
+        open(path);
     }
 
     Ok(())

src/cmd/clean.rs

@@ -1,44 +1,111 @@
+use super::command_prelude::*;
 use crate::get_book_dir;
 use anyhow::Context;
-use clap::{arg, App, Arg, ArgMatches};
 use mdbook::MDBook;
-use std::fs;
+use std::mem::take;
+use std::path::PathBuf;
+use std::{fmt, fs};
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("clean")
+pub fn make_subcommand() -> Command {
+    Command::new("clean")
         .about("Deletes a built book")
-        .arg(
-            Arg::new("dest-dir")
-                .short('d')
-                .long("dest-dir")
-                .value_name("dest-dir")
-                .help(
-                    "Output directory for the book{n}\
-                    Relative paths are interpreted relative to the book's root directory.{n}\
-                    If omitted, mdBook uses build.build-dir from book.toml or defaults to `./book`.",
-                ),
-        )
-        .arg(arg!([dir]
-            "Root directory for the book{n}\
-            (Defaults to the Current Directory when omitted)"
-        ))
+        .arg_dest_dir()
+        .arg_root_dir()
 }
 
 // Clean command implementation
 pub fn execute(args: &ArgMatches) -> mdbook::errors::Result<()> {
     let book_dir = get_book_dir(args);
-    let book = MDBook::load(&book_dir)?;
+    let book = MDBook::load(book_dir)?;
 
-    let dir_to_remove = match args.value_of("dest-dir") {
+    let dir_to_remove = match args.get_one::<PathBuf>("dest-dir") {
         Some(dest_dir) => dest_dir.into(),
         None => book.root.join(&book.config.build.build_dir),
     };
 
-    if dir_to_remove.exists() {
-        fs::remove_dir_all(&dir_to_remove)
-            .with_context(|| "Unable to remove the build directory")?;
-    }
+    let removed = Clean::new(&dir_to_remove)?;
+    println!("{removed}");
 
     Ok(())
 }
+
+/// Formats a number of bytes into a human readable SI-prefixed size.
+/// Returns a tuple of `(quantity, units)`.
+pub fn human_readable_bytes(bytes: u64) -> (f32, &'static str) {
+    static UNITS: [&str; 7] = ["B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"];
+    let bytes = bytes as f32;
+    let i = ((bytes.log2() / 10.0) as usize).min(UNITS.len() - 1);
+    (bytes / 1024_f32.powi(i as i32), UNITS[i])
+}
+
+#[derive(Debug)]
+pub struct Clean {
+    num_files_removed: u64,
+    num_dirs_removed: u64,
+    total_bytes_removed: u64,
+}
+
+impl Clean {
+    fn new(dir: &PathBuf) -> mdbook::errors::Result<Clean> {
+        let mut files = vec![dir.clone()];
+        let mut children = Vec::new();
+        let mut num_files_removed = 0;
+        let mut num_dirs_removed = 0;
+        let mut total_bytes_removed = 0;
+
+        if dir.exists() {
+            while !files.is_empty() {
+                for file in files {
+                    if let Ok(meta) = file.metadata() {
+                        // Note: This can over-count bytes removed for hard-linked
+                        // files. It also under-counts since it only counts the exact
+                        // byte sizes and not the block sizes.
+                        total_bytes_removed += meta.len();
+                    }
+                    if file.is_file() {
+                        num_files_removed += 1;
+                    } else if file.is_dir() {
+                        num_dirs_removed += 1;
+                        for entry in fs::read_dir(file)? {
+                            children.push(entry?.path());
+                        }
+                    }
+                }
+                files = take(&mut children);
+            }
+            fs::remove_dir_all(&dir).with_context(|| "Unable to remove the build directory")?;
+        }
+
+        Ok(Clean {
+            num_files_removed,
+            num_dirs_removed,
+            total_bytes_removed,
+        })
+    }
+}
+
+impl fmt::Display for Clean {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Removed ")?;
+        match (self.num_files_removed, self.num_dirs_removed) {
+            (0, 0) => write!(f, "0 files")?,
+            (0, 1) => write!(f, "1 directory")?,
+            (0, 2..) => write!(f, "{} directories", self.num_dirs_removed)?,
+            (1, _) => write!(f, "1 file")?,
+            (2.., _) => write!(f, "{} files", self.num_files_removed)?,
+        }
+
+        if self.total_bytes_removed == 0 {
+            Ok(())
+        } else {
+            // Don't show a fractional number of bytes.
+            if self.total_bytes_removed < 1024 {
+                write!(f, ", {}B total", self.total_bytes_removed)
+            } else {
+                let (bytes, unit) = human_readable_bytes(self.total_bytes_removed);
+                write!(f, ", {bytes:.2}{unit} total")
+            }
+        }
+    }
+}

src/cmd/command_prelude.rs

@@ -0,0 +1,59 @@
+//! Helpers for building the command-line arguments for commands.
+
+pub use clap::{arg, Arg, ArgMatches, Command};
+use std::path::PathBuf;
+
+pub trait CommandExt: Sized {
+    fn _arg(self, arg: Arg) -> Self;
+
+    fn arg_dest_dir(self) -> Self {
+        self._arg(
+            Arg::new("dest-dir")
+                .short('d')
+                .long("dest-dir")
+                .value_name("dest-dir")
+                .value_parser(clap::value_parser!(PathBuf))
+                .help(
+                    "Output directory for the book\n\
+                    Relative paths are interpreted relative to the book's root directory.\n\
+                    If omitted, mdBook uses build.build-dir from book.toml \
+                    or defaults to `./book`.",
+                ),
+        )
+    }
+
+    fn arg_root_dir(self) -> Self {
+        self._arg(
+            Arg::new("dir")
+                .help(
+                    "Root directory for the book\n\
+                    (Defaults to the current directory when omitted)",
+                )
+                .value_parser(clap::value_parser!(PathBuf)),
+        )
+    }
+
+    fn arg_open(self) -> Self {
+        self._arg(arg!(-o --open "Opens the compiled book in a web browser"))
+    }
+
+    #[cfg(any(feature = "watch", feature = "serve"))]
+    fn arg_watcher(self) -> Self {
+        #[cfg(feature = "watch")]
+        return self._arg(
+            Arg::new("watcher")
+                .long("watcher")
+                .value_parser(["poll", "native"])
+                .default_value("poll")
+                .help("The filesystem watching technique"),
+        );
+        #[cfg(not(feature = "watch"))]
+        return self;
+    }
+}
+
+impl CommandExt for Command {
+    fn _arg(self, arg: Arg) -> Self {
+        self.arg(arg)
+    }
+}

src/cmd/init.rs

@@ -1,5 +1,5 @@
 use crate::get_book_dir;
-use clap::{arg, App, Arg, ArgMatches};
+use clap::{arg, ArgMatches, Command as ClapCommand};
 use mdbook::config;
 use mdbook::errors::Result;
 use mdbook::MDBook;
@@ -8,30 +8,22 @@ use std::io::Write;
 use std::process::Command;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("init")
+pub fn make_subcommand() -> ClapCommand {
+    ClapCommand::new("init")
         .about("Creates the boilerplate structure and files for a new book")
-        // the {n} denotes a newline which will properly aligned in all help messages
-        .arg(arg!([dir]
-            "Directory to create the book in{n}\
-            (Defaults to the Current Directory when omitted)"
-        ))
+        .arg(
+            arg!([dir]
+                "Directory to create the book in\n\
+                (Defaults to the current directory when omitted)"
+            )
+            .value_parser(clap::value_parser!(std::path::PathBuf)),
+        )
         .arg(arg!(--theme "Copies the default theme into your source folder"))
         .arg(arg!(--force "Skips confirmation prompts"))
+        .arg(arg!(--title <title> "Sets the book title"))
         .arg(
-            Arg::new("title")
-                .long("title")
-                .takes_value(true)
-                .help("Sets the book title")
-                .required(false),
-        )
-        .arg(
-            Arg::new("ignore")
-                .long("ignore")
-                .takes_value(true)
-                .possible_values(&["none", "git"])
-                .help("Creates a VCS ignore file (i.e. .gitignore)")
-                .required(false),
+            arg!(--ignore <ignore> "Creates a VCS ignore file (i.e. .gitignore)")
+                .value_parser(["none", "git"]),
         )
 }
 
@@ -41,12 +33,12 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let mut builder = MDBook::init(&book_dir);
     let mut config = config::Config::default();
     // If flag `--theme` is present, copy theme to src
-    if args.is_present("theme") {
+    if args.get_flag("theme") {
         let theme_dir = book_dir.join("theme");
         println!();
         println!("Copying the default theme to {}", theme_dir.display());
         // Skip this if `--force` is present
-        if !args.is_present("force") && theme_dir.exists() {
+        if !args.get_flag("force") && theme_dir.exists() {
             println!("This could potentially overwrite files already present in that directory.");
             print!("\nAre you sure you want to continue? (y/n) ");
 
@@ -59,20 +51,22 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         }
     }
 
-    if let Some(ignore) = args.value_of("ignore") {
+    if let Some(ignore) = args.get_one::<String>("ignore").map(|s| s.as_str()) {
         match ignore {
             "git" => builder.create_gitignore(true),
             _ => builder.create_gitignore(false),
         };
-    } else {
+    } else if !args.get_flag("force") {
         println!("\nDo you want a .gitignore to be created? (y/n)");
         if confirm() {
             builder.create_gitignore(true);
         }
     }
 
-    config.book.title = if args.is_present("title") {
-        args.value_of("title").map(String::from)
+    config.book.title = if args.contains_id("title") {
+        args.get_one::<String>("title").map(String::from)
+    } else if args.get_flag("force") {
+        None
     } else {
         request_book_title()
     };
@@ -80,9 +74,9 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     if let Some(author) = get_author_name() {
         debug!("Obtained user name from gitconfig: {:?}", author);
         config.book.authors.push(author);
-        builder.with_config(config);
     }
 
+    builder.with_config(config);
     builder.build()?;
     println!("\nAll done, no errors...");
 
@@ -92,7 +86,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 /// Obtains author name from git config file by running the `git config` command.
 fn get_author_name() -> Option<String> {
     let output = Command::new("git")
-        .args(&["config", "--get", "user.name"])
+        .args(["config", "--get", "user.name"])
         .output()
         .ok()?;
 
@@ -122,8 +116,5 @@ fn confirm() -> bool {
     io::stdout().flush().unwrap();
     let mut s = String::new();
     io::stdin().read_line(&mut s).ok();
-    match &*s.trim() {
-        "Y" | "y" | "yes" | "Yes" => true,
-        _ => false,
-    }
+    matches!(s.trim(), "Y" | "y" | "yes" | "Yes")
 }

src/cmd/mod.rs

@@ -2,6 +2,7 @@
 
 pub mod build;
 pub mod clean;
+pub mod command_prelude;
 pub mod init;
 #[cfg(feature = "serve")]
 pub mod serve;

src/cmd/serve.rs

@@ -1,11 +1,11 @@
+use super::command_prelude::*;
 #[cfg(feature = "watch")]
 use super::watch;
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
+use clap::builder::NonEmptyStringValueParser;
 use futures_util::sink::SinkExt;
 use futures_util::StreamExt;
 use mdbook::errors::*;
-use mdbook::utils;
 use mdbook::utils::fs::get_404_output_file;
 use mdbook::MDBook;
 use std::net::{SocketAddr, ToSocketAddrs};
@@ -18,43 +18,31 @@ use warp::Filter;
 const LIVE_RELOAD_ENDPOINT: &str = "__livereload";
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("serve")
+pub fn make_subcommand() -> Command {
+    Command::new("serve")
         .about("Serves a book at http://localhost:3000, and rebuilds it on changes")
-        .arg(
-            Arg::new("dest-dir")
-                .short('d')
-                .long("dest-dir")
-                .value_name("dest-dir")
-                .help(
-                    "Output directory for the book{n}\
-                    Relative paths are interpreted relative to the book's root directory.{n}\
-                    If omitted, mdBook uses build.build-dir from book.toml or defaults to `./book`.",
-                ),
-        )
-        .arg(arg!([dir]
-            "Root directory for the book{n}\
-            (Defaults to the Current Directory when omitted)"
-        ))
+        .arg_dest_dir()
+        .arg_root_dir()
         .arg(
             Arg::new("hostname")
                 .short('n')
                 .long("hostname")
-                .takes_value(true)
+                .num_args(1)
                 .default_value("localhost")
-                .forbid_empty_values(true)
+                .value_parser(NonEmptyStringValueParser::new())
                 .help("Hostname to listen on for HTTP connections"),
         )
         .arg(
             Arg::new("port")
                 .short('p')
                 .long("port")
-                .takes_value(true)
+                .num_args(1)
                 .default_value("3000")
-                .forbid_empty_values(true)
+                .value_parser(NonEmptyStringValueParser::new())
                 .help("Port to use for HTTP connections"),
         )
-        .arg(arg!(-o --open "Opens the compiled book in a web browser"))
+        .arg_open()
+        .arg_watcher()
 }
 
 // Serve command implementation
@@ -62,17 +50,17 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let book_dir = get_book_dir(args);
     let mut book = MDBook::load(&book_dir)?;
 
-    let port = args.value_of("port").unwrap();
-    let hostname = args.value_of("hostname").unwrap();
-    let open_browser = args.is_present("open");
+    let port = args.get_one::<String>("port").unwrap();
+    let hostname = args.get_one::<String>("hostname").unwrap();
+    let open_browser = args.get_flag("open");
 
-    let address = format!("{}:{}", hostname, port);
+    let address = format!("{hostname}:{port}");
 
     let update_config = |book: &mut MDBook| {
         book.config
-            .set("output.html.live-reload-endpoint", &LIVE_RELOAD_ENDPOINT)
+            .set("output.html.live-reload-endpoint", LIVE_RELOAD_ENDPOINT)
             .expect("live-reload-endpoint update failed");
-        if let Some(dest_dir) = args.value_of("dest-dir") {
+        if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
             book.config.build.build_dir = dest_dir.into();
         }
         // Override site-url for local serving of the 404 file
@@ -89,8 +77,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let input_404 = book
         .config
         .get("output.html.input-404")
-        .map(toml::Value::as_str)
-        .and_then(std::convert::identity) // flatten
+        .and_then(toml::Value::as_str)
         .map(ToString::to_string);
     let file_404 = get_404_output_file(&input_404);
 
@@ -102,7 +89,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         serve(build_dir, sockaddr, reload_tx, &file_404);
     });
 
-    let serving_url = format!("http://{}", address);
+    let serving_url = format!("http://{address}");
     info!("Serving on: {}", serving_url);
 
     if open_browser {
@@ -110,23 +97,12 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     }
 
     #[cfg(feature = "watch")]
-    watch::trigger_on_change(&book, move |paths, book_dir| {
-        info!("Files changed: {:?}", paths);
-        info!("Building book...");
-
-        // FIXME: This area is really ugly because we need to re-set livereload :(
-        let result = MDBook::load(&book_dir).and_then(|mut b| {
-            update_config(&mut b);
-            b.build()
-        });
-
-        if let Err(e) = result {
-            error!("Unable to load the book");
-            utils::log_backtrace(&e);
-        } else {
+    {
+        let watcher = watch::WatcherKind::from_str(args.get_one::<String>("watcher").unwrap());
+        watch::rebuild_on_change(watcher, &book_dir, &update_config, &move || {
             let _ = tx.send(Message::text("reload"));
-        }
-    });
+        });
+    }
 
     let _ = thread_handle.join();
 

src/cmd/test.rs

@@ -1,54 +1,58 @@
+use super::command_prelude::*;
 use crate::get_book_dir;
-use clap::{arg, App, Arg, ArgMatches};
+use clap::builder::NonEmptyStringValueParser;
+use clap::ArgAction;
 use mdbook::errors::Result;
 use mdbook::MDBook;
+use std::path::PathBuf;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("test")
+pub fn make_subcommand() -> Command {
+    Command::new("test")
         .about("Tests that a book's Rust code samples compile")
+        // FIXME: --dest-dir is unused by the test command, it should be removed
+        .arg_dest_dir()
+        .arg_root_dir()
         .arg(
-            Arg::new("dest-dir")
-                .short('d')
-                .long("dest-dir")
-                .value_name("dest-dir")
+            Arg::new("chapter")
+                .short('c')
+                .long("chapter")
+                .value_name("chapter"),
+        )
+        .arg(
+            Arg::new("library-path")
+                .short('L')
+                .long("library-path")
+                .value_name("dir")
+                .value_delimiter(',')
+                .value_parser(NonEmptyStringValueParser::new())
+                .action(ArgAction::Append)
                 .help(
-                    "Output directory for the book{n}\
-                    Relative paths are interpreted relative to the book's root directory.{n}\
-                    If omitted, mdBook uses build.build-dir from book.toml or defaults to `./book`.",
+                    "A comma-separated list of directories to add to the crate \
+                    search path when building tests",
                 ),
         )
-        .arg(arg!([dir]
-            "Root directory for the book{n}\
-            (Defaults to the Current Directory when omitted)"
-        ))
-        .arg(Arg::new("library-path")
-            .short('L')
-            .long("library-path")
-            .value_name("dir")
-            .takes_value(true)
-            .use_delimiter(true)
-            .require_delimiter(true)
-            .multiple_values(true)
-            .multiple_occurrences(true)
-            .forbid_empty_values(true)
-            .help("A comma-separated list of directories to add to {n}the crate search path when building tests"))
 }
 
 // test command implementation
 pub fn execute(args: &ArgMatches) -> Result<()> {
     let library_paths: Vec<&str> = args
-        .values_of("library-path")
-        .map(std::iter::Iterator::collect)
+        .get_many("library-path")
+        .map(|it| it.map(String::as_str).collect())
         .unwrap_or_default();
+
+    let chapter: Option<&str> = args.get_one::<String>("chapter").map(|s| s.as_str());
+
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = MDBook::load(book_dir)?;
 
-    if let Some(dest_dir) = args.value_of("dest-dir") {
-        book.config.build.build_dir = dest_dir.into();
+    if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
+        book.config.build.build_dir = dest_dir.to_path_buf();
     }
-
-    book.test(library_paths)?;
+    match chapter {
+        Some(_) => book.test_chapter(library_paths, chapter),
+        None => book.test(library_paths),
+    }?;
 
     Ok(())
 }

src/cmd/watch.rs

@@ -1,34 +1,35 @@
+use super::command_prelude::*;
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
 use mdbook::errors::Result;
-use mdbook::utils;
 use mdbook::MDBook;
-use notify::Watcher;
 use std::path::{Path, PathBuf};
-use std::sync::mpsc::channel;
-use std::thread::sleep;
-use std::time::Duration;
+
+mod native;
+mod poller;
 
 // Create clap subcommand arguments
-pub fn make_subcommand<'help>() -> App<'help> {
-    App::new("watch")
+pub fn make_subcommand() -> Command {
+    Command::new("watch")
         .about("Watches a book's files and rebuilds it on changes")
-        .arg(
-            Arg::new("dest-dir")
-                .short('d')
-                .long("dest-dir")
-                .value_name("dest-dir")
-                .help(
-                    "Output directory for the book{n}\
-                    Relative paths are interpreted relative to the book's root directory.{n}\
-                    If omitted, mdBook uses build.build-dir from book.toml or defaults to `./book`.",
-                ),
-        )
-        .arg(arg!([dir]
-            "Root directory for the book{n}\
-            (Defaults to the Current Directory when omitted)"
-        ))
-        .arg(arg!(-o --open "Opens the compiled book in a web browser"))
+        .arg_dest_dir()
+        .arg_root_dir()
+        .arg_open()
+        .arg_watcher()
+}
+
+pub enum WatcherKind {
+    Poll,
+    Native,
+}
+
+impl WatcherKind {
+    pub fn from_str(s: &str) -> WatcherKind {
+        match s {
+            "poll" => WatcherKind::Poll,
+            "native" => WatcherKind::Native,
+            _ => panic!("unsupported watcher {s}"),
+        }
+    }
 }
 
 // Watch command implementation
@@ -37,53 +38,37 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     let mut book = MDBook::load(&book_dir)?;
 
     let update_config = |book: &mut MDBook| {
-        if let Some(dest_dir) = args.value_of("dest-dir") {
+        if let Some(dest_dir) = args.get_one::<PathBuf>("dest-dir") {
             book.config.build.build_dir = dest_dir.into();
         }
     };
     update_config(&mut book);
 
-    if args.is_present("open") {
+    if args.get_flag("open") {
         book.build()?;
-        open(book.build_dir_for("html").join("index.html"));
+        let path = book.build_dir_for("html").join("index.html");
+        if !path.exists() {
+            error!("No chapter available to open");
+            std::process::exit(1)
+        }
+        open(path);
     }
 
-    trigger_on_change(&book, |paths, book_dir| {
-        info!("Files changed: {:?}\nBuilding book...\n", paths);
-        let result = MDBook::load(&book_dir).and_then(|mut b| {
-            update_config(&mut b);
-            b.build()
-        });
-
-        if let Err(e) = result {
-            error!("Unable to build the book");
-            utils::log_backtrace(&e);
-        }
-    });
+    let watcher = WatcherKind::from_str(args.get_one::<String>("watcher").unwrap());
+    rebuild_on_change(watcher, &book_dir, &update_config, &|| {});
 
     Ok(())
 }
 
-fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
-    if paths.is_empty() {
-        return vec![];
-    }
-
-    match find_gitignore(book_root) {
-        Some(gitignore_path) => {
-            match gitignore::File::new(gitignore_path.as_path()) {
-                Ok(exclusion_checker) => filter_ignored_files(exclusion_checker, paths),
-                Err(_) => {
-                    // We're unable to read the .gitignore file, so we'll silently allow everything.
-                    // Please see discussion: https://github.com/rust-lang/mdBook/pull/1051
-                    paths.iter().map(|path| path.to_path_buf()).collect()
-                }
-            }
-        }
-        None => {
-            // There is no .gitignore file.
-            paths.iter().map(|path| path.to_path_buf()).collect()
-        }
+pub fn rebuild_on_change(
+    kind: WatcherKind,
+    book_dir: &Path,
+    update_config: &dyn Fn(&mut MDBook),
+    post_build: &dyn Fn(),
+) {
+    match kind {
+        WatcherKind::Poll => self::poller::rebuild_on_change(book_dir, update_config, post_build),
+        WatcherKind::Native => self::native::rebuild_on_change(book_dir, update_config, post_build),
     }
 }
 
@@ -93,78 +78,3 @@ fn find_gitignore(book_root: &Path) -> Option<PathBuf> {
         .map(|p| p.join(".gitignore"))
         .find(|p| p.exists())
 }
-
-fn filter_ignored_files(exclusion_checker: gitignore::File, paths: &[PathBuf]) -> Vec<PathBuf> {
-    paths
-        .iter()
-        .filter(|path| match exclusion_checker.is_excluded(path) {
-            Ok(exclude) => !exclude,
-            Err(error) => {
-                warn!(
-                    "Unable to determine if {:?} is excluded: {:?}. Including it.",
-                    &path, error
-                );
-                true
-            }
-        })
-        .map(|path| path.to_path_buf())
-        .collect()
-}
-
-/// Calls the closure when a book source file is changed, blocking indefinitely.
-pub fn trigger_on_change<F>(book: &MDBook, closure: F)
-where
-    F: Fn(Vec<PathBuf>, &Path),
-{
-    use notify::DebouncedEvent::*;
-    use notify::RecursiveMode::*;
-
-    // Create a channel to receive the events.
-    let (tx, rx) = channel();
-
-    let mut watcher = match notify::watcher(tx, Duration::from_secs(1)) {
-        Ok(w) => w,
-        Err(e) => {
-            error!("Error while trying to watch the files:\n\n\t{:?}", e);
-            std::process::exit(1)
-        }
-    };
-
-    // Add the source directory to the watcher
-    if let Err(e) = watcher.watch(book.source_dir(), Recursive) {
-        error!("Error while watching {:?}:\n    {:?}", book.source_dir(), e);
-        std::process::exit(1);
-    };
-
-    let _ = watcher.watch(book.theme_dir(), Recursive);
-
-    // Add the book.toml file to the watcher if it exists
-    let _ = watcher.watch(book.root.join("book.toml"), NonRecursive);
-
-    info!("Listening for changes...");
-
-    loop {
-        let first_event = rx.recv().unwrap();
-        sleep(Duration::from_millis(50));
-        let other_events = rx.try_iter();
-
-        let all_events = std::iter::once(first_event).chain(other_events);
-
-        let paths = all_events
-            .filter_map(|event| {
-                debug!("Received filesystem event: {:?}", event);
-
-                match event {
-                    Create(path) | Write(path) | Remove(path) | Rename(_, path) => Some(path),
-                    _ => None,
-                }
-            })
-            .collect::<Vec<_>>();
-
-        let paths = remove_ignored_files(&book.root, &paths[..]);
-
-        if !paths.is_empty() {
-            closure(paths, &book.root);
-        }
-    }
-}

src/cmd/watch/native.rs

@@ -0,0 +1,189 @@
+//! A filesystem watcher using native operating system facilities.
+
+use ignore::gitignore::Gitignore;
+use mdbook::MDBook;
+use std::path::{Path, PathBuf};
+use std::sync::mpsc::channel;
+use std::thread::sleep;
+use std::time::Duration;
+
+pub fn rebuild_on_change(
+    book_dir: &Path,
+    update_config: &dyn Fn(&mut MDBook),
+    post_build: &dyn Fn(),
+) {
+    use notify::RecursiveMode::*;
+
+    let mut book = MDBook::load(book_dir).unwrap_or_else(|e| {
+        error!("failed to load book: {e}");
+        std::process::exit(1);
+    });
+
+    // Create a channel to receive the events.
+    let (tx, rx) = channel();
+
+    let mut debouncer = match notify_debouncer_mini::new_debouncer(Duration::from_secs(1), tx) {
+        Ok(d) => d,
+        Err(e) => {
+            error!("Error while trying to watch the files:\n\n\t{:?}", e);
+            std::process::exit(1)
+        }
+    };
+    let watcher = debouncer.watcher();
+
+    // Add the source directory to the watcher
+    if let Err(e) = watcher.watch(&book.source_dir(), Recursive) {
+        error!("Error while watching {:?}:\n    {:?}", book.source_dir(), e);
+        std::process::exit(1);
+    };
+
+    let _ = watcher.watch(&book.theme_dir(), Recursive);
+
+    // Add the book.toml file to the watcher if it exists
+    let _ = watcher.watch(&book.root.join("book.toml"), NonRecursive);
+
+    for dir in &book.config.build.extra_watch_dirs {
+        let path = book.root.join(dir);
+        let canonical_path = path.canonicalize().unwrap_or_else(|e| {
+            error!("Error while watching extra directory {path:?}:\n    {e}");
+            std::process::exit(1);
+        });
+
+        if let Err(e) = watcher.watch(&canonical_path, Recursive) {
+            error!(
+                "Error while watching extra directory {:?}:\n    {:?}",
+                canonical_path, e
+            );
+            std::process::exit(1);
+        }
+    }
+
+    info!("Listening for changes...");
+
+    loop {
+        let first_event = rx.recv().unwrap();
+        sleep(Duration::from_millis(50));
+        let other_events = rx.try_iter();
+
+        let all_events = std::iter::once(first_event).chain(other_events);
+
+        let paths: Vec<_> = all_events
+            .filter_map(|event| match event {
+                Ok(events) => Some(events),
+                Err(error) => {
+                    log::warn!("error while watching for changes: {error}");
+                    None
+                }
+            })
+            .flatten()
+            .map(|event| event.path)
+            .collect();
+
+        // If we are watching files outside the current repository (via extra-watch-dirs), then they are definitionally
+        // ignored by gitignore. So we handle this case by including such files into the watched paths list.
+        let any_external_paths = paths.iter().filter(|p| !p.starts_with(&book.root)).cloned();
+        let mut paths = remove_ignored_files(&book.root, &paths[..]);
+        paths.extend(any_external_paths);
+
+        if !paths.is_empty() {
+            info!("Files changed: {paths:?}");
+            match MDBook::load(book_dir) {
+                Ok(mut b) => {
+                    update_config(&mut b);
+                    if let Err(e) = b.build() {
+                        error!("failed to build the book: {e:?}");
+                    } else {
+                        post_build();
+                    }
+                    book = b;
+                }
+                Err(e) => error!("failed to load book config: {e:?}"),
+            }
+        }
+    }
+}
+
+fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
+    if paths.is_empty() {
+        return vec![];
+    }
+
+    match super::find_gitignore(book_root) {
+        Some(gitignore_path) => {
+            let (ignore, err) = Gitignore::new(&gitignore_path);
+            if let Some(err) = err {
+                warn!(
+                    "error reading gitignore `{}`: {err}",
+                    gitignore_path.display()
+                );
+            }
+            filter_ignored_files(ignore, paths)
+        }
+        None => {
+            // There is no .gitignore file.
+            paths.iter().map(|path| path.to_path_buf()).collect()
+        }
+    }
+}
+
+// Note: The usage of `canonicalize` may encounter occasional failures on the Windows platform, presenting a potential risk.
+// For more details, refer to [Pull Request #2229](https://github.com/rust-lang/mdBook/pull/2229#discussion_r1408665981).
+fn filter_ignored_files(ignore: Gitignore, paths: &[PathBuf]) -> Vec<PathBuf> {
+    let ignore_root = ignore
+        .path()
+        .canonicalize()
+        .expect("ignore root canonicalize error");
+
+    paths
+        .iter()
+        .filter(|path| {
+            let relative_path = pathdiff::diff_paths(&path, &ignore_root)
+                .expect("One of the paths should be an absolute");
+            !ignore
+                .matched_path_or_any_parents(&relative_path, relative_path.is_dir())
+                .is_ignore()
+        })
+        .map(|path| path.to_path_buf())
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ignore::gitignore::GitignoreBuilder;
+    use std::env;
+
+    #[test]
+    fn test_filter_ignored_files() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+        let should_remain = current_dir.join("record.text");
+        let should_filter = current_dir.join("index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+
+    #[test]
+    fn filter_ignored_files_should_handle_parent_dir() {
+        let current_dir = env::current_dir().unwrap();
+
+        let ignore = GitignoreBuilder::new(&current_dir)
+            .add_line(None, "*.html")
+            .unwrap()
+            .build()
+            .unwrap();
+
+        let parent_dir = current_dir.join("..");
+        let should_remain = parent_dir.join("record.text");
+        let should_filter = parent_dir.join("index.html");
+
+        let remain = filter_ignored_files(ignore, &[should_remain.clone(), should_filter]);
+        assert_eq!(remain, vec![should_remain])
+    }
+}

src/cmd/watch/poller.rs

@@ -0,0 +1,386 @@
+//! A simple poll-based filesystem watcher.
+//!
+//! This exists because the native change notifications have historically had
+//! lots of problems. Various operating systems and different filesystems have
+//! had problems correctly reporting changes.
+
+use ignore::gitignore::Gitignore;
+use mdbook::MDBook;
+use pathdiff::diff_paths;
+use std::collections::HashMap;
+use std::fs::FileType;
+use std::path::{Path, PathBuf};
+use std::time::{Duration, Instant, SystemTime};
+use walkdir::WalkDir;
+
+/// Calls the closure when a book source file is changed, blocking indefinitely.
+pub fn rebuild_on_change(
+    book_dir: &Path,
+    update_config: &dyn Fn(&mut MDBook),
+    post_build: &dyn Fn(),
+) {
+    let mut book = MDBook::load(book_dir).unwrap_or_else(|e| {
+        error!("failed to load book: {e}");
+        std::process::exit(1);
+    });
+
+    let mut watcher = Watcher::new(book_dir);
+
+    info!("Watching for changes...");
+    // Scan once to initialize the starting point.
+    watcher.set_roots(&book);
+    watcher.scan();
+
+    // Track average scan time, to help investigate if the poller is taking
+    // undesirably long. This is not a rigorous benchmark, just a rough
+    // estimate.
+    const AVG_SIZE: usize = 60;
+    let mut avgs = vec![0.0; AVG_SIZE];
+    let mut avg_i = 0;
+
+    loop {
+        std::thread::sleep(Duration::new(1, 0));
+        watcher.set_roots(&book);
+        let start = Instant::now();
+        let paths = watcher.scan();
+        let elapsed = start.elapsed().as_secs_f64();
+        avgs[avg_i] = elapsed;
+        avg_i += 1;
+        if avg_i >= AVG_SIZE {
+            avg_i = 0;
+            let avg = avgs.iter().sum::<f64>() / (avgs.len() as f64);
+            trace!(
+                "scan average time: {avg:.2}s, scan size is {}",
+                watcher.path_data.len()
+            );
+        }
+
+        if !paths.is_empty() {
+            info!("Files changed: {paths:?}");
+            match MDBook::load(book_dir) {
+                Ok(mut b) => {
+                    update_config(&mut b);
+                    if let Err(e) = b.build() {
+                        error!("failed to build the book: {e:?}");
+                    } else {
+                        post_build();
+                    }
+                    book = b;
+                }
+                Err(e) => error!("failed to load book config: {e:?}"),
+            }
+        }
+    }
+}
+
+#[derive(PartialEq)]
+struct PathData {
+    file_type: FileType,
+    mtime: SystemTime,
+    size: u64,
+}
+
+/// A very simple poll-watcher that scans for modified files.
+#[derive(Default)]
+struct Watcher {
+    /// The root paths where it will recursively scan for changes.
+    root_paths: Vec<PathBuf>,
+    /// Data about files on disk.
+    path_data: HashMap<PathBuf, PathData>,
+    /// Filters paths that will be watched.
+    ignore: Option<(PathBuf, Gitignore)>,
+}
+
+impl Watcher {
+    fn new(book_root: &Path) -> Watcher {
+        // FIXME: ignore should be reloaded when it changes.
+        let ignore = super::find_gitignore(book_root).map(|gitignore_path| {
+            let (ignore, err) = Gitignore::new(&gitignore_path);
+            if let Some(err) = err {
+                warn!(
+                    "error reading gitignore `{}`: {err}",
+                    gitignore_path.display()
+                );
+            }
+            // Note: The usage of `canonicalize` may encounter occasional
+            // failures on the Windows platform, presenting a potential risk.
+            // For more details, refer to [Pull Request
+            // #2229](https://github.com/rust-lang/mdBook/pull/2229#discussion_r1408665981).
+            let ignore_path = ignore
+                .path()
+                .canonicalize()
+                .expect("ignore root canonicalize error");
+            (ignore_path, ignore)
+        });
+
+        Watcher {
+            ignore,
+            ..Default::default()
+        }
+    }
+
+    /// Sets the root directories where scanning will start.
+    fn set_roots(&mut self, book: &MDBook) {
+        let mut root_paths = vec![
+            book.source_dir(),
+            book.theme_dir(),
+            book.root.join("book.toml"),
+        ];
+        root_paths.extend(
+            book.config
+                .build
+                .extra_watch_dirs
+                .iter()
+                .map(|path| book.root.join(path)),
+        );
+        if let Some(html_config) = book.config.html_config() {
+            root_paths.extend(
+                html_config
+                    .additional_css
+                    .iter()
+                    .chain(html_config.additional_js.iter())
+                    .map(|path| book.root.join(path)),
+            );
+        }
+
+        self.root_paths = root_paths;
+    }
+
+    /// Scans for changes.
+    ///
+    /// Returns the paths that have changed.
+    fn scan(&mut self) -> Vec<PathBuf> {
+        let ignore = &self.ignore;
+        let new_path_data: HashMap<_, _> = self
+            .root_paths
+            .iter()
+            .filter(|root| root.exists())
+            .flat_map(|root| {
+                WalkDir::new(root)
+                    .follow_links(true)
+                    .into_iter()
+                    .filter_entry(|entry| {
+                        if let Some((ignore_path, ignore)) = ignore {
+                            let path = entry.path();
+                            // Canonicalization helps with removing `..` and
+                            // `.` entries, which can cause issues with
+                            // diff_paths.
+                            let path = path.canonicalize().unwrap_or_else(|_| path.to_path_buf());
+                            let relative_path = diff_paths(&path, &ignore_path)
+                                .expect("One of the paths should be an absolute");
+                            if ignore
+                                .matched_path_or_any_parents(&relative_path, relative_path.is_dir())
+                                .is_ignore()
+                            {
+                                trace!("ignoring {path:?}");
+                                return false;
+                            }
+                        }
+                        true
+                    })
+                    .filter_map(move |entry| {
+                        let entry = match entry {
+                            Ok(e) => e,
+                            Err(e) => {
+                                debug!("failed to scan {root:?}: {e}");
+                                return None;
+                            }
+                        };
+                        if entry.file_type().is_dir() {
+                            // Changes to directories themselves aren't
+                            // particularly interesting.
+                            return None;
+                        }
+                        let path = entry.path().to_path_buf();
+
+                        let meta = match entry.metadata() {
+                            Ok(meta) => meta,
+                            Err(e) => {
+                                debug!("failed to scan {path:?}: {e}");
+                                return None;
+                            }
+                        };
+                        let mtime = meta.modified().unwrap_or(SystemTime::UNIX_EPOCH);
+                        let pd = PathData {
+                            file_type: meta.file_type(),
+                            mtime,
+                            size: meta.len(),
+                        };
+                        Some((path, pd))
+                    })
+            })
+            .collect();
+        let mut paths = Vec::new();
+        for (new_path, new_data) in &new_path_data {
+            match self.path_data.get(new_path) {
+                Some(old_data) => {
+                    if new_data != old_data {
+                        paths.push(new_path.to_path_buf());
+                    }
+                }
+                None => {
+                    paths.push(new_path.clone());
+                }
+            }
+        }
+        for old_path in self.path_data.keys() {
+            if !new_path_data.contains_key(old_path) {
+                paths.push(old_path.to_path_buf());
+            }
+        }
+        self.path_data = new_path_data;
+        paths
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Helper for testing the watcher.
+    fn check_watch_behavior(
+        gitignore_path: &str,
+        gitignore: &str,
+        book_root_path: &str,
+        ignored: &[&str],
+        not_ignored: &[&str],
+        extra_setup: &dyn Fn(&Path),
+    ) {
+        // Create the book and initialize things.
+        let temp = tempfile::Builder::new()
+            .prefix("mdbook-")
+            .tempdir()
+            .unwrap();
+        let root = temp.path();
+        let book_root = root.join(book_root_path);
+        // eprintln!("book_root={book_root:?}",);
+        MDBook::init(&book_root).build().unwrap();
+        std::fs::write(root.join(gitignore_path), gitignore).unwrap();
+        let create = |paths: &[&str]| {
+            let mut paths = paths
+                .iter()
+                .map(|path| root.join(path))
+                .inspect(|path| {
+                    std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+                    std::fs::write(path, "initial content").unwrap();
+                })
+                .map(|path| path.canonicalize().unwrap())
+                .collect::<Vec<_>>();
+            paths.sort();
+            paths
+        };
+        let ignored = create(ignored);
+        let not_ignored = create(not_ignored);
+        extra_setup(&book_root);
+        // Create a watcher and check its behavior.
+        let book = MDBook::load(&book_root).unwrap();
+        let mut watcher = Watcher::new(&book_root);
+        watcher.set_roots(&book);
+        // Do an initial scan to initialize its state.
+        watcher.scan();
+        // Verify the steady state is empty.
+        let changed = watcher.scan();
+        assert_eq!(changed, Vec::<PathBuf>::new());
+        // Modify all files, and verify that only not_ignored are detected.
+        for path in ignored.iter().chain(not_ignored.iter()) {
+            std::fs::write(path, "modified").unwrap();
+        }
+        let changed = watcher.scan();
+        let mut changed = changed
+            .into_iter()
+            .map(|p| p.canonicalize().unwrap())
+            .collect::<Vec<_>>();
+        changed.sort();
+        assert_eq!(changed, not_ignored);
+        // Verify again that steady state is empty.
+        let changed = watcher.scan();
+        assert_eq!(changed, Vec::<PathBuf>::new());
+    }
+
+    #[test]
+    fn test_ignore() {
+        // Basic gitignore test.
+        check_watch_behavior(
+            "foo/.gitignore",
+            "*.tmp",
+            "foo",
+            &["foo/src/somefile.tmp"],
+            &["foo/src/chapter.md"],
+            &|_book_root| {},
+        );
+    }
+
+    #[test]
+    fn test_ignore_in_parent() {
+        // gitignore is in the parent of the book
+        check_watch_behavior(
+            ".gitignore",
+            "*.tmp\nsomedir/\n/inroot\n/foo/src/inbook\n",
+            "foo",
+            &[
+                "foo/src/somefile.tmp",
+                "foo/src/somedir/somefile",
+                "inroot/somefile",
+                "foo/src/inbook/somefile",
+            ],
+            &["foo/src/inroot/somefile"],
+            &|_book_root| {},
+        );
+    }
+
+    #[test]
+    fn test_ignore_canonical() {
+        // test with path with ..
+        check_watch_behavior(
+            ".gitignore",
+            "*.tmp\nsomedir/\n/foo/src/inbook\n",
+            "bar/../foo",
+            &[
+                "foo/src/somefile.tmp",
+                "foo/src/somedir/somefile",
+                "foo/src/inbook/somefile",
+            ],
+            &["foo/src/chapter.md"],
+            &|_book_root| {},
+        );
+    }
+
+    #[test]
+    fn test_scan_extra_watch() {
+        // Check behavior with extra-watch-dirs
+        check_watch_behavior(
+            ".gitignore",
+            "*.tmp\n/outside-root/ignoreme\n/foo/examples/ignoreme\n",
+            "foo",
+            &[
+                "foo/src/somefile.tmp",
+                "foo/examples/example.tmp",
+                "outside-root/somefile.tmp",
+                "outside-root/ignoreme",
+                "foo/examples/ignoreme",
+            ],
+            &[
+                "foo/src/chapter.md",
+                "foo/examples/example.rs",
+                "foo/examples/example2.rs",
+                "outside-root/image.png",
+            ],
+            &|book_root| {
+                std::fs::write(
+                    book_root.join("book.toml"),
+                    r#"
+                        [book]
+                        title = "foo"
+
+                        [build]
+                        extra-watch-dirs = [
+                            "examples",
+                            "../outside-root",
+                        ]
+                    "#,
+                )
+                .unwrap();
+            },
+        );
+    }
+}

src/config.rs

@@ -49,6 +49,7 @@
 
 #![deny(missing_docs)]
 
+use log::{debug, trace, warn};
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use std::collections::HashMap;
 use std::env;
@@ -57,7 +58,7 @@ use std::io::Read;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use toml::value::Table;
-use toml::{self, Value};
+use toml::Value;
 
 use crate::errors::*;
 use crate::utils::{self, toml_ext::TomlExt};
@@ -144,7 +145,7 @@ impl Config {
                 if let serde_json::Value::Object(ref map) = parsed_value {
                     // To `set` each `key`, we wrap them as `prefix.key`
                     for (k, v) in map {
-                        let full_key = format!("{}.{}", key, k);
+                        let full_key = format!("{key}.{k}");
                         self.set(&full_key, v).expect("unreachable");
                     }
                     return;
@@ -227,10 +228,10 @@ impl Config {
         let value = Value::try_from(value)
             .with_context(|| "Unable to represent the item as a JSON Value")?;
 
-        if index.starts_with("book.") {
-            self.book.update_value(&index[5..], value);
-        } else if index.starts_with("build.") {
-            self.build.update_value(&index[6..], value);
+        if let Some(key) = index.strip_prefix("book.") {
+            self.book.update_value(key, value);
+        } else if let Some(key) = index.strip_prefix("build.") {
+            self.build.update_value(key, value);
         } else {
             self.rest.insert(index, value);
         }
@@ -295,7 +296,7 @@ impl Default for Config {
     }
 }
 
-impl<'de> Deserialize<'de> for Config {
+impl<'de> serde::Deserialize<'de> for Config {
     fn deserialize<D: Deserializer<'de>>(de: D) -> std::result::Result<Self, D::Error> {
         let raw = Value::deserialize(de)?;
 
@@ -307,10 +308,12 @@ impl<'de> Deserialize<'de> for Config {
             warn!("`description` under a table called `[book]`, move the `destination` entry");
             warn!("from `[output.html]`, renamed to `build-dir`, under a table called");
             warn!("`[build]`, and it should all work.");
-            warn!("Documentation: http://rust-lang.github.io/mdBook/format/config.html");
+            warn!("Documentation: https://rust-lang.github.io/mdBook/format/config.html");
             return Ok(Config::from_legacy(raw));
         }
 
+        warn_on_invalid_fields(&raw);
+
         use serde::de::Error;
         let mut table = match raw {
             Value::Table(t) => t,
@@ -371,14 +374,18 @@ impl Serialize for Config {
 }
 
 fn parse_env(key: &str) -> Option<String> {
-    const PREFIX: &str = "MDBOOK_";
+    key.strip_prefix("MDBOOK_")
+        .map(|key| key.to_lowercase().replace("__", ".").replace('_', "-"))
+}
 
-    if key.starts_with(PREFIX) {
-        let key = &key[PREFIX.len()..];
+fn warn_on_invalid_fields(table: &Value) {
+    let valid_items = ["book", "build", "rust", "output", "preprocessor"];
 
-        Some(key.to_lowercase().replace("__", ".").replace("_", "-"))
-    } else {
-        None
+    let table = table.as_table().expect("root must be a table");
+    for item in table.keys() {
+        if !valid_items.contains(&item.as_str()) {
+            warn!("Invalid field {:?} in book.toml", &item);
+        }
     }
 }
 
@@ -414,9 +421,15 @@ pub struct BookConfig {
     /// Location of the book source relative to the book's root directory.
     pub src: PathBuf,
     /// Does this book support more than one language?
+    // TODO: Remove this field in 0.5, it is unused:
+    // https://github.com/rust-lang/mdBook/issues/2636
+    #[serde(skip_serializing)]
     pub multilingual: bool,
     /// The main language of the book.
     pub language: Option<String>,
+    /// The direction of text in the book: Left-to-right (LTR) or Right-to-left (RTL).
+    /// When not specified, the text direction is derived from [`BookConfig::language`].
+    pub text_direction: Option<TextDirection>,
 }
 
 impl Default for BookConfig {
@@ -428,6 +441,43 @@ impl Default for BookConfig {
             src: PathBuf::from("src"),
             multilingual: false,
             language: Some(String::from("en")),
+            text_direction: None,
+        }
+    }
+}
+
+impl BookConfig {
+    /// Gets the realized text direction, either from [`BookConfig::text_direction`]
+    /// or derived from [`BookConfig::language`], to be used by templating engines.
+    pub fn realized_text_direction(&self) -> TextDirection {
+        if let Some(direction) = self.text_direction {
+            direction
+        } else {
+            TextDirection::from_lang_code(self.language.as_deref().unwrap_or_default())
+        }
+    }
+}
+
+/// Text direction to use for HTML output
+#[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
+pub enum TextDirection {
+    /// Left to right.
+    #[serde(rename = "ltr")]
+    LeftToRight,
+    /// Right to left
+    #[serde(rename = "rtl")]
+    RightToLeft,
+}
+
+impl TextDirection {
+    /// Gets the text direction from language code
+    pub fn from_lang_code(code: &str) -> Self {
+        match code {
+            // list sourced from here: https://github.com/abarrak/rtl/blob/master/lib/rtl/core.rb#L16
+            "ar" | "ara" | "arc" | "ae" | "ave" | "egy" | "he" | "heb" | "nqo" | "pal" | "phn"
+            | "sam" | "syc" | "syr" | "fa" | "per" | "fas" | "ku" | "kur" | "ur" | "urd"
+            | "pus" | "ps" | "yi" | "yid" => TextDirection::RightToLeft,
+            _ => TextDirection::LeftToRight,
         }
     }
 }
@@ -444,6 +494,8 @@ pub struct BuildConfig {
     /// Should the default preprocessors always be used when they are
     /// compatible with the renderer?
     pub use_default_preprocessors: bool,
+    /// Extra directories to trigger rebuild when watching/serving
+    pub extra_watch_dirs: Vec<PathBuf>,
 }
 
 impl Default for BuildConfig {
@@ -452,6 +504,7 @@ impl Default for BuildConfig {
             build_dir: PathBuf::from("book"),
             create_missing: true,
             use_default_preprocessors: true,
+            extra_watch_dirs: Vec::new(),
         }
     }
 }
@@ -467,6 +520,9 @@ pub struct RustConfig {
 #[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
 /// Rust edition to use for the code.
 pub enum RustEdition {
+    /// The 2024 edition of Rust
+    #[serde(rename = "2024")]
+    E2024,
     /// The 2021 edition of Rust
     #[serde(rename = "2021")]
     E2021,
@@ -489,7 +545,9 @@ pub struct HtmlConfig {
     /// The theme to use if the browser requests the dark version of the site.
     /// Defaults to 'navy'.
     pub preferred_dark_theme: Option<String>,
-    /// Use "smart quotes" instead of the usual `"` character.
+    /// Supports smart quotes, apostrophes, ellipsis, en-dash, and em-dash.
+    pub smart_punctuation: bool,
+    /// Deprecated alias for `smart_punctuation`.
     pub curly_quotes: bool,
     /// Should mathjax be enabled?
     pub mathjax_support: bool,
@@ -507,6 +565,8 @@ pub struct HtmlConfig {
     /// Playground settings.
     #[serde(alias = "playpen")]
     pub playground: Playground,
+    /// Code settings.
+    pub code: Code,
     /// Print settings.
     pub print: Print,
     /// Don't render section labels.
@@ -533,10 +593,9 @@ pub struct HtmlConfig {
     /// directly jumping to editing the currently viewed page.
     /// Contains {path} that is replaced with chapter source file path
     pub edit_url_template: Option<String>,
-    /// Endpoint of websocket, for livereload usage. Value loaded from .toml file
-    /// is ignored, because our code overrides this field with the value [`LIVE_RELOAD_ENDPOINT`]
-    ///
-    /// [`LIVE_RELOAD_ENDPOINT`]: cmd::serve::LIVE_RELOAD_ENDPOINT
+    /// Endpoint of websocket, for livereload usage. Value loaded from .toml
+    /// file is ignored, because our code overrides this field with an
+    /// internal value (`LIVE_RELOAD_ENDPOINT)
     ///
     /// This config item *should not be edited* by the end user.
     #[doc(hidden)]
@@ -544,6 +603,9 @@ pub struct HtmlConfig {
     /// The mapping from old pages to new pages/URLs to use when generating
     /// redirects.
     pub redirect: HashMap<String, String>,
+    /// If this option is turned on, "cache bust" static files by adding
+    /// hashes to their file names.
+    pub hash_files: bool,
 }
 
 impl Default for HtmlConfig {
@@ -552,6 +614,7 @@ impl Default for HtmlConfig {
             theme: None,
             default_theme: None,
             preferred_dark_theme: None,
+            smart_punctuation: false,
             curly_quotes: false,
             mathjax_support: false,
             copy_fonts: true,
@@ -560,6 +623,7 @@ impl Default for HtmlConfig {
             additional_js: Vec::new(),
             fold: Fold::default(),
             playground: Playground::default(),
+            code: Code::default(),
             print: Print::default(),
             no_section_label: false,
             search: None,
@@ -571,6 +635,7 @@ impl Default for HtmlConfig {
             cname: None,
             live_reload_endpoint: None,
             redirect: HashMap::new(),
+            hash_files: false,
         }
     }
 }
@@ -584,6 +649,11 @@ impl HtmlConfig {
             None => root.join("theme"),
         }
     }
+
+    /// Returns `true` if smart punctuation is enabled.
+    pub fn smart_punctuation(&self) -> bool {
+        self.smart_punctuation || self.curly_quotes
+    }
 }
 
 /// Configuration for how to render the print icon, print.html, and print.css.
@@ -617,7 +687,7 @@ pub struct Fold {
     pub level: u8,
 }
 
-/// Configuration for tweaking how the the HTML renderer handles the playground.
+/// Configuration for tweaking how the HTML renderer handles the playground.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
 pub struct Playground {
@@ -646,6 +716,14 @@ impl Default for Playground {
     }
 }
 
+/// Configuration for tweaking how the HTML renderer handles code blocks.
+#[derive(Debug, Default, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(default, rename_all = "kebab-case")]
+pub struct Code {
+    /// A prefix string to hide lines per language (one or more chars).
+    pub hidelines: HashMap<String, String>,
+}
+
 /// Configuration of the search functionality of the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
@@ -677,6 +755,11 @@ pub struct Search {
     /// Copy JavaScript files for the search functionality to the output directory?
     /// Default: `true`.
     pub copy_js: bool,
+    /// Specifies search settings for the given path.
+    ///
+    /// The path can be for a specific chapter, or a directory. This will
+    /// merge recursively, with more specific paths taking precedence.
+    pub chapter: HashMap<String, SearchChapterSettings>,
 }
 
 impl Default for Search {
@@ -693,10 +776,19 @@ impl Default for Search {
             expand: true,
             heading_split_level: 3,
             copy_js: true,
+            chapter: HashMap::new(),
         }
     }
 }
 
+/// Search options for chapters (or paths).
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
+#[serde(default, rename_all = "kebab-case")]
+pub struct SearchChapterSettings {
+    /// Whether or not indexing is enabled, default `true`.
+    pub enable: Option<bool>,
+}
+
 /// Allows you to "update" any arbitrary field in a struct by round-tripping via
 /// a `toml::Value`.
 ///
@@ -707,7 +799,7 @@ trait Updateable<'de>: Serialize + Deserialize<'de> {
         let mut raw = Value::try_from(&self).expect("unreachable");
 
         if let Ok(value) = Value::try_from(value) {
-            let _ = raw.insert(key, value);
+            raw.insert(key, value);
         } else {
             return;
         }
@@ -724,6 +816,7 @@ impl<'de, T> Updateable<'de> for T where T: Serialize + Deserialize<'de> {}
 mod tests {
     use super::*;
     use crate::utils::fs::get_404_output_file;
+    use serde_json::json;
 
     const COMPLEX_CONFIG: &str = r#"
         [book]
@@ -742,7 +835,7 @@ mod tests {
         [output.html]
         theme = "./themedir"
         default-theme = "rust"
-        curly-quotes = true
+        smart-punctuation = true
         google-analytics = "123456"
         additional-css = ["./foo/bar/baz.css"]
         git-repository-url = "https://foo.com/"
@@ -772,11 +865,13 @@ mod tests {
             multilingual: true,
             src: PathBuf::from("source"),
             language: Some(String::from("ja")),
+            text_direction: None,
         };
         let build_should_be = BuildConfig {
             build_dir: PathBuf::from("outputs"),
             create_missing: false,
             use_default_preprocessors: true,
+            extra_watch_dirs: Vec::new(),
         };
         let rust_should_be = RustConfig { edition: None };
         let playground_should_be = Playground {
@@ -787,7 +882,7 @@ mod tests {
             runnable: true,
         };
         let html_should_be = HtmlConfig {
-            curly_quotes: true,
+            smart_punctuation: true,
             google_analytics: Some(String::from("123456")),
             additional_css: vec![PathBuf::from("./foo/bar/baz.css")],
             theme: Some(PathBuf::from("./themedir")),
@@ -828,7 +923,7 @@ mod tests {
         "#;
 
         let got = Config::from_str(src).unwrap();
-        assert_eq!(got.html_config().unwrap().playground.runnable, false);
+        assert!(!got.html_config().unwrap().playground.runnable);
     }
 
     #[test]
@@ -967,7 +1062,7 @@ mod tests {
         [output.html]
         destination = "my-book" # the output files will be generated in `root/my-book` instead of `root/book`
         theme = "my-theme"
-        curly-quotes = true
+        smart-punctuation = true
         google-analytics = "123456"
         additional-css = ["custom.css", "custom2.css"]
         additional-js = ["custom.js"]
@@ -987,11 +1082,12 @@ mod tests {
             build_dir: PathBuf::from("my-book"),
             create_missing: true,
             use_default_preprocessors: true,
+            extra_watch_dirs: Vec::new(),
         };
 
         let html_should_be = HtmlConfig {
             theme: Some(PathBuf::from("my-theme")),
-            curly_quotes: true,
+            smart_punctuation: true,
             google_analytics: Some(String::from("123456")),
             additional_css: vec![PathBuf::from("custom.css"), PathBuf::from("custom2.css")],
             additional_js: vec![PathBuf::from("custom.js")],
@@ -1037,7 +1133,7 @@ mod tests {
     fn encode_env_var(key: &str) -> String {
         format!(
             "MDBOOK_{}",
-            key.to_uppercase().replace('.', "__").replace("-", "_")
+            key.to_uppercase().replace('.', "__").replace('-', "_")
         )
     }
 
@@ -1061,11 +1157,10 @@ mod tests {
     }
 
     #[test]
-    #[allow(clippy::approx_constant)]
     fn update_config_using_env_var_and_complex_value() {
         let mut cfg = Config::default();
         let key = "foo-bar.baz";
-        let value = json!({"array": [1, 2, 3], "number": 3.14});
+        let value = json!({"array": [1, 2, 3], "number": 13.37});
         let value_str = serde_json::to_string(&value).unwrap();
 
         assert!(cfg.get(key).is_none());
@@ -1123,6 +1218,73 @@ mod tests {
         assert_eq!(&get_404_output_file(&html_config.input_404), "missing.html");
     }
 
+    #[test]
+    fn text_direction_ltr() {
+        let src = r#"
+        [book]
+        text-direction = "ltr"
+        "#;
+
+        let got = Config::from_str(src).unwrap();
+        assert_eq!(got.book.text_direction, Some(TextDirection::LeftToRight));
+    }
+
+    #[test]
+    fn text_direction_rtl() {
+        let src = r#"
+        [book]
+        text-direction = "rtl"
+        "#;
+
+        let got = Config::from_str(src).unwrap();
+        assert_eq!(got.book.text_direction, Some(TextDirection::RightToLeft));
+    }
+
+    #[test]
+    fn text_direction_none() {
+        let src = r#"
+        [book]
+        "#;
+
+        let got = Config::from_str(src).unwrap();
+        assert_eq!(got.book.text_direction, None);
+    }
+
+    #[test]
+    fn test_text_direction() {
+        let mut cfg = BookConfig::default();
+
+        // test deriving the text direction from language codes
+        cfg.language = Some("ar".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+
+        cfg.language = Some("he".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+
+        cfg.language = Some("en".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        cfg.language = Some("ja".into());
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        // test forced direction
+        cfg.language = Some("ar".into());
+        cfg.text_direction = Some(TextDirection::LeftToRight);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        cfg.language = Some("ar".into());
+        cfg.text_direction = Some(TextDirection::RightToLeft);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+
+        cfg.language = Some("en".into());
+        cfg.text_direction = Some(TextDirection::LeftToRight);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::LeftToRight);
+
+        cfg.language = Some("en".into());
+        cfg.text_direction = Some(TextDirection::RightToLeft);
+        assert_eq!(cfg.realized_text_direction(), TextDirection::RightToLeft);
+    }
+
     #[test]
     #[should_panic(expected = "Invalid configuration file")]
     fn invalid_language_type_error() {
@@ -1184,15 +1346,48 @@ mod tests {
         "#;
         let got = Config::from_str(src).unwrap();
         let html_config = got.html_config().unwrap();
-        assert_eq!(html_config.print.enable, false);
-        assert_eq!(html_config.print.page_break, true);
+        assert!(!html_config.print.enable);
+        assert!(html_config.print.page_break);
         let src = r#"
         [output.html.print]
         page-break = false
         "#;
         let got = Config::from_str(src).unwrap();
         let html_config = got.html_config().unwrap();
-        assert_eq!(html_config.print.enable, true);
-        assert_eq!(html_config.print.page_break, false);
+        assert!(html_config.print.enable);
+        assert!(!html_config.print.page_break);
+    }
+
+    #[test]
+    fn curly_quotes_or_smart_punctuation() {
+        let src = r#"
+        [book]
+        title = "mdBook Documentation"
+
+        [output.html]
+        smart-punctuation = true
+        "#;
+        let config = Config::from_str(src).unwrap();
+        assert_eq!(config.html_config().unwrap().smart_punctuation(), true);
+
+        let src = r#"
+        [book]
+        title = "mdBook Documentation"
+
+        [output.html]
+        curly-quotes = true
+        "#;
+        let config = Config::from_str(src).unwrap();
+        assert_eq!(config.html_config().unwrap().smart_punctuation(), true);
+
+        let src = r#"
+        [book]
+        title = "mdBook Documentation"
+        "#;
+        let config = Config::from_str(src).unwrap();
+        assert_eq!(
+            config.html_config().unwrap_or_default().smart_punctuation(),
+            false
+        );
     }
 }

src/front-end/css/ayu-highlight.css

@@ -8,7 +8,6 @@ Original by Dempfi (https://github.com/dempfi/ayu)
   overflow-x: auto;
   background: #191f26;
   color: #e6e1cf;
-  padding: 0.5em;
 }
 
 .hljs-comment,

src/front-end/css/chrome.css

@@ -1,13 +1,5 @@
 /* CSS for UI elements (a.k.a. chrome) */
 
-@import 'variables.css';
-
-::-webkit-scrollbar {
-    background: var(--bg);
-}
-::-webkit-scrollbar-thumb {
-    background: var(--scrollbar);
-}
 html {
     scrollbar-color: var(--scrollbar) var(--bg);
 }
@@ -18,6 +10,19 @@ a > .hljs {
     color: var(--links);
 }
 
+/*
+    body-container is necessary because mobile browsers don't seem to like
+    overflow-x on the body tag when there is a <meta name="viewport"> tag.
+*/
+#body-container {
+    /*
+        This is used when the sidebar pushes the body content off the side of
+        the screen on small screens. Without it, dragging on mobile Safari
+        will want to reposition the viewport in a weird way.
+    */
+    overflow-x: clip;
+}
+
 /* Menu Bar */
 
 #menu-bar,
@@ -30,14 +35,14 @@ a > .hljs {
     display: flex;
     flex-wrap: wrap;
     background-color: var(--bg);
-    border-bottom-color: var(--bg);
-    border-bottom-width: 1px;
-    border-bottom-style: solid;
+    border-block-end-color: var(--bg);
+    border-block-end-width: 1px;
+    border-block-end-style: solid;
 }
 #menu-bar.sticky,
-.js #menu-bar-hover-placeholder:hover + #menu-bar,
-.js #menu-bar:hover,
-.js.sidebar-visible #menu-bar {
+#menu-bar-hover-placeholder:hover + #menu-bar,
+#menu-bar:hover,
+html.sidebar-visible #menu-bar {
     position: -webkit-sticky;
     position: sticky;
     top: 0 !important;
@@ -49,7 +54,7 @@ a > .hljs {
     height: var(--menu-bar-height);
 }
 #menu-bar.bordered {
-    border-bottom-color: var(--table-border-color);
+    border-block-end-color: var(--table-border-color);
 }
 #menu-bar i, #menu-bar .icon-button {
     position: relative;
@@ -86,7 +91,7 @@ a > .hljs {
     display: flex;
     margin: 0 5px;
 }
-.no-js .left-buttons {
+html:not(.js) .left-buttons button {
     display: none;
 }
 
@@ -102,7 +107,7 @@ a > .hljs {
     overflow: hidden;
     text-overflow: ellipsis;
 }
-.js .menu-title {
+.menu-title {
     cursor: pointer;
 }
 
@@ -153,7 +158,7 @@ a > .hljs {
 }
 
 .nav-wrapper {
-    margin-top: 50px;
+    margin-block-start: 50px;
     display: none;
 }
 
@@ -166,23 +171,34 @@ a > .hljs {
     background-color: var(--sidebar-bg);
 }
 
-.previous {
-    float: left;
-}
+/* Only Firefox supports flow-relative values */
+.previous { float: left; }
+[dir=rtl] .previous { float: right; }
 
+/* Only Firefox supports flow-relative values */
 .next {
     float: right;
     right: var(--page-padding);
 }
+[dir=rtl] .next {
+    float: left;
+    right: unset;
+    left: var(--page-padding);
+}
+
+/* Use the correct buttons for RTL layouts*/
+[dir=rtl] .previous i.fa-angle-left:before {content:"\f105";}
+[dir=rtl] .next i.fa-angle-right:before { content:"\f104"; }
 
 @media only screen and (max-width: 1080px) {
     .nav-wide-wrapper { display: none; }
     .nav-wrapper { display: block; }
 }
 
+/* sidebar-visible */
 @media only screen and (max-width: 1380px) {
-    .sidebar-visible .nav-wide-wrapper { display: none; }
-    .sidebar-visible .nav-wrapper { display: block; }
+    #sidebar-toggle-anchor:checked ~ .page-wrapper .nav-wide-wrapper { display: none; }
+    #sidebar-toggle-anchor:checked ~ .page-wrapper .nav-wrapper { display: block; }
 }
 
 /* Inline code */
@@ -208,26 +224,92 @@ pre {
 pre > .buttons {
     position: absolute;
     z-index: 100;
-    right: 5px;
-    top: 5px;
+    right: 0px;
+    top: 2px;
+    margin: 0px;
+    padding: 2px 0px;
 
     color: var(--sidebar-fg);
     cursor: pointer;
+    visibility: hidden;
+    opacity: 0;
+    transition: visibility 0.1s linear, opacity 0.1s linear;
+}
+pre:hover > .buttons {
+    visibility: visible;
+    opacity: 1
 }
 pre > .buttons :hover {
     color: var(--sidebar-active);
+    border-color: var(--icons-hover);
+    background-color: var(--theme-hover);
 }
 pre > .buttons i {
-    margin-left: 8px;
+    margin-inline-start: 8px;
 }
 pre > .buttons button {
-    color: inherit;
-    background: transparent;
-    border: none;
     cursor: inherit;
+    margin: 0px 5px;
+    padding: 4px 4px 3px 5px;
+    font-size: 23px;
+
+    border-style: solid;
+    border-width: 1px;
+    border-radius: 4px;
+    border-color: var(--icons);
+    background-color: var(--theme-popup-bg);
+    transition: 100ms;
+    transition-property: color,border-color,background-color;
+    color: var(--icons);
 }
+
+pre > .buttons button.clip-button {
+    padding: 2px 4px 0px 6px;
+}
+pre > .buttons button.clip-button::before {
+    /* clipboard image from octicons (https://github.com/primer/octicons/tree/v2.0.0) MIT license
+     */
+    content: url('data:image/svg+xml,<svg width="21" height="20" viewBox="0 0 24 25" \
+xmlns="http://www.w3.org/2000/svg" aria-label="Copy to clipboard">\
+<path d="M18 20h2v3c0 1-1 2-2 2H2c-.998 0-2-1-2-2V5c0-.911.755-1.667 1.667-1.667h5A3.323 3.323 0 \
+0110 0a3.323 3.323 0 013.333 3.333h5C19.245 3.333 20 4.09 20 5v8.333h-2V9H2v14h16v-3zM3 \
+7h14c0-.911-.793-1.667-1.75-1.667H13.5c-.957 0-1.75-.755-1.75-1.666C11.75 2.755 10.957 2 10 \
+2s-1.75.755-1.75 1.667c0 .911-.793 1.666-1.75 1.666H4.75C3.793 5.333 3 6.09 3 7z"/>\
+<path d="M4 19h6v2H4zM12 11H4v2h8zM4 17h4v-2H4zM15 15v-3l-4.5 4.5L15 21v-3l8.027-.032L23 15z"/>\
+</svg>');
+    filter: var(--copy-button-filter);
+}
+pre > .buttons button.clip-button:hover::before {
+    filter: var(--copy-button-filter-hover);
+}
+
+@media (pointer: coarse) {
+    pre > .buttons button {
+        /* On mobile, make it easier to tap buttons. */
+        padding: 0.3rem 1rem;
+    }
+
+    .sidebar-resize-indicator {
+        /* Hide resize indicator on devices with limited accuracy */
+        display: none;
+    }
+}
+pre > code {
+    display: block;
+    padding: 1rem;
+}
+
+/* FIXME: ACE editors overlap their buttons because ACE does absolute
+   positioning within the code block which breaks padding. The only solution I
+   can think of is to move the padding to the outer pre tag (or insert a div
+   wrapper), but that would require fixing a whole bunch of CSS rules.
+*/
+.hljs.ace_editor {
+  padding: 0rem 0rem;
+}
+
 pre > .result {
-    margin-top: 10px;
+    margin-block-start: 10px;
 }
 
 /* Search */
@@ -238,8 +320,14 @@ pre > .result {
 
 mark {
     border-radius: 2px;
-    padding: 0 3px 1px 3px;
-    margin: 0 -3px -1px -3px;
+    padding-block-start: 0;
+    padding-block-end: 1px;
+    padding-inline-start: 3px;
+    padding-inline-end: 3px;
+    margin-block-start: 0;
+    margin-block-end: -1px;
+    margin-inline-start: -3px;
+    margin-inline-end: -3px;
     background-color: var(--search-mark-bg);
     transition: background-color 300ms linear;
     cursor: pointer;
@@ -251,14 +339,17 @@ mark.fade-out {
 }
 
 .searchbar-outer {
-    margin-left: auto;
-    margin-right: auto;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     max-width: var(--content-max-width);
 }
 
 #searchbar {
     width: 100%;
-    margin: 5px auto 0px auto;
+    margin-block-start: 5px;
+    margin-block-end: 0;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     padding: 10px 16px;
     transition: box-shadow 300ms ease-in-out;
     border: 1px solid var(--searchbar-border-color);
@@ -274,20 +365,23 @@ mark.fade-out {
 .searchresults-header {
     font-weight: bold;
     font-size: 1em;
-    padding: 18px 0 0 5px;
+    padding-block-start: 18px;
+    padding-block-end: 0;
+    padding-inline-start: 5px;
+    padding-inline-end: 0;
     color: var(--searchresults-header-fg);
 }
 
 .searchresults-outer {
-    margin-left: auto;
-    margin-right: auto;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     max-width: var(--content-max-width);
-    border-bottom: 1px dashed var(--searchresults-border-color);
+    border-block-end: 1px dashed var(--searchresults-border-color);
 }
 
 ul#searchresults {
     list-style: none;
-    padding-left: 20px;
+    padding-inline-start: 20px;
 }
 ul#searchresults li {
     margin: 10px 0px;
@@ -300,7 +394,10 @@ ul#searchresults li.focus {
 ul#searchresults span.teaser {
     display: block;
     clear: both;
-    margin: 5px 0 0 20px;
+    margin-block-start: 5px;
+    margin-block-end: 0;
+    margin-inline-start: 20px;
+    margin-inline-end: 0;
     font-size: 0.8em;
 }
 ul#searchresults span.teaser em {
@@ -323,13 +420,33 @@ ul#searchresults span.teaser em {
     background-color: var(--sidebar-bg);
     color: var(--sidebar-fg);
 }
+.sidebar-iframe-inner {
+    --padding: 10px;
+
+    background-color: var(--sidebar-bg);
+    padding: var(--padding);
+    margin: 0;
+    font-size: 1.4rem;
+    color: var(--sidebar-fg);
+    min-height: calc(100vh - var(--padding) * 2);
+}
+.sidebar-iframe-outer {
+    border: none;
+    height: 100%;
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    left: 0;
+    right: 0;
+}
+[dir=rtl] .sidebar { left: unset; right: 0; }
 .sidebar-resizing {
     -moz-user-select: none;
     -webkit-user-select: none;
     -ms-user-select: none;
     user-select: none;
 }
-.js:not(.sidebar-resizing) .sidebar {
+html:not(.sidebar-resizing) .sidebar {
     transition: transform 0.3s; /* Animation: slide away */
 }
 .sidebar code {
@@ -348,16 +465,35 @@ ul#searchresults span.teaser em {
     position: absolute;
     cursor: col-resize;
     width: 0;
-    right: 0;
+    right: calc(var(--sidebar-resize-indicator-width) * -1);
     top: 0;
     bottom: 0;
+    display: flex;
+    align-items: center;
+}
+
+.sidebar-resize-handle .sidebar-resize-indicator {
+    width: 100%;
+    height: 12px;
+    background-color: var(--icons);
+    margin-inline-start: var(--sidebar-resize-indicator-space);
+}
+
+[dir=rtl] .sidebar .sidebar-resize-handle {
+    left: calc(var(--sidebar-resize-indicator-width) * -1);
+    right: unset;
 }
 .js .sidebar .sidebar-resize-handle {
     cursor: col-resize;
-    width: 5px;
+    width: calc(var(--sidebar-resize-indicator-width) - var(--sidebar-resize-indicator-space));
 }
-.sidebar-hidden .sidebar {
-    transform: translateX(calc(0px - var(--sidebar-width)));
+/* sidebar-hidden */
+#sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+    transform: translateX(calc(0px - var(--sidebar-width) - var(--sidebar-resize-indicator-width)));
+    z-index: -1;
+}
+[dir=rtl] #sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+    transform: translateX(calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width)));
 }
 .sidebar::-webkit-scrollbar {
     background: var(--sidebar-bg);
@@ -366,19 +502,26 @@ ul#searchresults span.teaser em {
     background: var(--scrollbar);
 }
 
-.sidebar-visible .page-wrapper {
-    transform: translateX(var(--sidebar-width));
+/* sidebar-visible */
+#sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: translateX(calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width)));
+}
+[dir=rtl] #sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: translateX(calc(0px - var(--sidebar-width) - var(--sidebar-resize-indicator-width)));
 }
 @media only screen and (min-width: 620px) {
-    .sidebar-visible .page-wrapper {
+    #sidebar-toggle-anchor:checked ~ .page-wrapper {
+        transform: none;
+        margin-inline-start: calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width));
+    }
+    [dir=rtl] #sidebar-toggle-anchor:checked ~ .page-wrapper {
         transform: none;
-        margin-left: var(--sidebar-width);
     }
 }
 
 .chapter {
     list-style: none outside none;
-    padding-left: 0;
+    padding-inline-start: 0;
     line-height: 2.2em;
 }
 
@@ -408,7 +551,7 @@ ul#searchresults span.teaser em {
 .chapter li > a.toggle {
     cursor: pointer;
     display: block;
-    margin-left: auto;
+    margin-inline-start: auto;
     padding: 0 10px;
     user-select: none;
     opacity: 0.68;
@@ -425,7 +568,7 @@ ul#searchresults span.teaser em {
 
 .chapter li.chapter-item {
     line-height: 1.5em;
-    margin-top: 0.6em;
+    margin-block-start: 0.6em;
 }
 
 .chapter li.expanded > a.toggle div {
@@ -448,7 +591,7 @@ ul#searchresults span.teaser em {
 
 .section {
     list-style: none outside none;
-    padding-left: 20px;
+    padding-inline-start: 20px;
     line-height: 1.9em;
 }
 
@@ -468,7 +611,10 @@ ul#searchresults span.teaser em {
     padding: 0;
     list-style: none;
     display: none;
+    /* Don't let the children's background extend past the rounded corners. */
+    overflow: hidden;
 }
+[dir=rtl] .theme-popup { left: unset;  right: 10px; }
 .theme-popup .default {
     color: var(--icons);
 }
@@ -476,10 +622,10 @@ ul#searchresults span.teaser em {
     width: 100%;
     border: 0;
     margin: 0;
-    padding: 2px 10px;
+    padding: 2px 20px;
     line-height: 25px;
     white-space: nowrap;
-    text-align: left;
+    text-align: start;
     cursor: pointer;
     color: inherit;
     background: inherit;
@@ -488,8 +634,10 @@ ul#searchresults span.teaser em {
 .theme-popup .theme:hover {
     background-color: var(--theme-hover);
 }
-.theme-popup .theme:hover:first-child,
-.theme-popup .theme:hover:last-child {
-    border-top-left-radius: inherit;
-    border-top-right-radius: inherit;
+
+.theme-selected::before {
+    display: inline-block;
+    content: "✓";
+    margin-inline-start: -14px;
+    width: 14px;
 }

src/front-end/css/general.css

@@ -0,0 +1,279 @@
+/* Base styles and content styles */
+
+:root {
+    /* Browser default font-size is 16px, this way 1 rem = 10px */
+    font-size: 62.5%;
+    color-scheme: var(--color-scheme);
+}
+
+html {
+    font-family: "Open Sans", sans-serif;
+    color: var(--fg);
+    background-color: var(--bg);
+    text-size-adjust: none;
+    -webkit-text-size-adjust: none;
+}
+
+body {
+    margin: 0;
+    font-size: 1.6rem;
+    overflow-x: hidden;
+}
+
+code {
+    font-family: var(--mono-font) !important;
+    font-size: var(--code-font-size);
+    direction: ltr !important;
+}
+
+/* make long words/inline code not x overflow */
+main {
+    overflow-wrap: break-word;
+}
+
+/* make wide tables scroll if they overflow */
+.table-wrapper {
+    overflow-x: auto;
+}
+
+/* Don't change font size in headers. */
+h1 code, h2 code, h3 code, h4 code, h5 code, h6 code {
+    font-size: unset;
+}
+
+.left { float: left; }
+.right { float: right; }
+.boring { opacity: 0.6; }
+.hide-boring .boring { display: none; }
+.hidden { display: none !important; }
+
+h2, h3 { margin-block-start: 2.5em; }
+h4, h5 { margin-block-start: 2em; }
+
+.header + .header h3,
+.header + .header h4,
+.header + .header h5 {
+    margin-block-start: 1em;
+}
+
+h1:target::before,
+h2:target::before,
+h3:target::before,
+h4:target::before,
+h5:target::before,
+h6:target::before {
+    display: inline-block;
+    content: "»";
+    margin-inline-start: -30px;
+    width: 30px;
+}
+
+/* This is broken on Safari as of version 14, but is fixed
+   in Safari Technology Preview 117 which I think will be Safari 14.2.
+   https://bugs.webkit.org/show_bug.cgi?id=218076
+*/
+:target {
+    /* Safari does not support logical properties */
+    scroll-margin-top: calc(var(--menu-bar-height) + 0.5em);
+}
+
+.page {
+    outline: 0;
+    padding: 0 var(--page-padding);
+    margin-block-start: calc(0px - var(--menu-bar-height)); /* Compensate for the #menu-bar-hover-placeholder */
+}
+.page-wrapper {
+    box-sizing: border-box;
+    background-color: var(--bg);
+}
+.no-js .page-wrapper,
+.js:not(.sidebar-resizing) .page-wrapper {
+    transition: margin-left 0.3s ease, transform 0.3s ease; /* Animation: slide away */
+}
+[dir=rtl] .js:not(.sidebar-resizing) .page-wrapper {
+    transition: margin-right 0.3s ease, transform 0.3s ease; /* Animation: slide away */
+}
+
+.content {
+    overflow-y: auto;
+    padding: 0 5px 50px 5px;
+}
+.content main {
+    margin-inline-start: auto;
+    margin-inline-end: auto;
+    max-width: var(--content-max-width);
+}
+.content p { line-height: 1.45em; }
+.content ol { line-height: 1.45em; }
+.content ul { line-height: 1.45em; }
+.content a { text-decoration: none; }
+.content a:hover { text-decoration: underline; }
+.content img, .content video { max-width: 100%; }
+.content .header:link,
+.content .header:visited {
+    color: var(--fg);
+}
+.content .header:link,
+.content .header:visited:hover {
+    text-decoration: none;
+}
+
+table {
+    margin: 0 auto;
+    border-collapse: collapse;
+}
+table td {
+    padding: 3px 20px;
+    border: 1px var(--table-border-color) solid;
+}
+table thead {
+    background: var(--table-header-bg);
+}
+table thead td {
+    font-weight: 700;
+    border: none;
+}
+table thead th {
+    padding: 3px 20px;
+}
+table thead tr {
+    border: 1px var(--table-header-bg) solid;
+}
+/* Alternate background colors for rows */
+table tbody tr:nth-child(2n) {
+    background: var(--table-alternate-bg);
+}
+
+
+blockquote {
+    margin: 20px 0;
+    padding: 0 20px;
+    color: var(--fg);
+    background-color: var(--quote-bg);
+    border-block-start: .1em solid var(--quote-border);
+    border-block-end: .1em solid var(--quote-border);
+}
+
+.warning {
+    margin: 20px;
+    padding: 0 20px;
+    border-inline-start: 2px solid var(--warning-border);
+}
+
+.warning:before {
+    position: absolute;
+    width: 3rem;
+    height: 3rem;
+    margin-inline-start: calc(-1.5rem - 21px);
+    content: "ⓘ";
+    text-align: center;
+    background-color: var(--bg);
+    color: var(--warning-border);
+    font-weight: bold;
+    font-size: 2rem;
+}
+
+blockquote .warning:before {
+    background-color: var(--quote-bg);
+}
+
+kbd {
+    background-color: var(--table-border-color);
+    border-radius: 4px;
+    border: solid 1px var(--theme-popup-border);
+    box-shadow: inset 0 -1px 0 var(--theme-hover);
+    display: inline-block;
+    font-size: var(--code-font-size);
+    font-family: var(--mono-font);
+    line-height: 10px;
+    padding: 4px 5px;
+    vertical-align: middle;
+}
+
+sup {
+    /* Set the line-height for superscript and footnote references so that there
+       isn't an awkward space appearing above lines that contain the footnote.
+
+       See https://github.com/rust-lang/mdBook/pull/2443#discussion_r1813773583
+       for an explanation.
+    */
+    line-height: 0;
+}
+
+.footnote-definition {
+    font-size: 0.9em;
+}
+/* The default spacing for a list is a little too large. */
+.footnote-definition ul,
+.footnote-definition ol {
+    padding-left: 20px;
+}
+.footnote-definition > li {
+    /* Required to position the ::before target */
+    position: relative;
+}
+.footnote-definition > li:target {
+    scroll-margin-top: 50vh;
+}
+.footnote-reference:target {
+    scroll-margin-top: 50vh;
+}
+/* Draws a border around the footnote (including the marker) when it is selected.
+   TODO: If there are multiple linkbacks, highlight which one you just came
+   from so you know which one to click.
+*/
+.footnote-definition > li:target::before {
+    border: 2px solid var(--footnote-highlight);
+    border-radius: 6px;
+    position: absolute;
+    top: -8px;
+    right: -8px;
+    bottom: -8px;
+    left: -32px;
+    pointer-events: none;
+    content: "";
+}
+/* Pulses the footnote reference so you can quickly see where you left off reading.
+   This could use some improvement.
+*/
+@media not (prefers-reduced-motion) {
+    .footnote-reference:target  {
+        animation: fn-highlight 0.8s;
+        border-radius: 2px;
+    }
+
+    @keyframes fn-highlight {
+        from {
+            background-color: var(--footnote-highlight);
+        }
+    }
+}
+
+.tooltiptext {
+    position: absolute;
+    visibility: hidden;
+    color: #fff;
+    background-color: #333;
+    transform: translateX(-50%); /* Center by moving tooltip 50% of its width left */
+    left: -8px; /* Half of the width of the icon */
+    top: -35px;
+    font-size: 0.8em;
+    text-align: center;
+    border-radius: 6px;
+    padding: 5px 8px;
+    margin: 5px;
+    z-index: 1000;
+}
+.tooltipped .tooltiptext {
+    visibility: visible;
+}
+
+.chapter li.part-title {
+    color: var(--sidebar-fg);
+    margin: 5px 0px;
+    font-weight: bold;
+}
+
+.result-no-output {
+    font-style: italic;
+}

src/front-end/css/highlight.css

@@ -16,6 +16,7 @@
 .hljs-variable,
 .hljs-template-variable,
 .hljs-attribute,
+.hljs-attr,
 .hljs-tag,
 .hljs-name,
 .hljs-regexp,
@@ -61,7 +62,6 @@
   overflow-x: auto;
   background: #f6f7f6;
   color: #000;
-  padding: 0.5em;
 }
 
 .hljs-emphasis {

src/front-end/css/print.css

@@ -7,8 +7,8 @@
 }
 
 #page-wrapper.page-wrapper {
-    transform: none;
-    margin-left: 0px;
+    transform: none !important;
+    margin-inline-start: 0px;
     overflow-y: initial;
 }
 
@@ -23,11 +23,7 @@
 }
 
 code {
-    background-color: #666666;
-    border-radius: 5px;
-
-    /* Force background to be printed in Chrome */
-    -webkit-print-color-adjust: exact;
+    direction: ltr !important;
 }
 
 pre > .buttons {

src/front-end/css/tomorrow-night.css

@@ -1,7 +1,7 @@
 /* Tomorrow Night Theme */
-/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
+/* https://github.com/jmblog/color-themes-for-highlightjs */
 /* Original theme - https://github.com/chriskempson/tomorrow-theme */
-/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
+/* https://github.com/jmblog/color-themes-for-highlightjs */
 
 /* Tomorrow Comment */
 .hljs-comment {
@@ -11,6 +11,7 @@
 /* Tomorrow Red */
 .hljs-variable,
 .hljs-attribute,
+.hljs-attr,
 .hljs-tag,
 .hljs-regexp,
 .ruby .hljs-constant,
@@ -54,6 +55,7 @@
 
 /* Tomorrow Aqua */
 .hljs-title,
+.hljs-section,
 .css .hljs-hexcolor {
   color: #8abeb7;
 }
@@ -81,8 +83,6 @@
   overflow-x: auto;
   background: #1d1f21;
   color: #c5c8c6;
-  padding: 0.5em;
-  -webkit-text-size-adjust: none;
 }
 
 .coffeescript .javascript,

src/front-end/css/variables.css

@@ -2,10 +2,15 @@
 /* Globals */
 
 :root {
-    --sidebar-width: 300px;
+    --sidebar-target-width: 300px;
+    --sidebar-width: min(var(--sidebar-target-width), 80vw);
+    --sidebar-resize-indicator-width: 8px;
+    --sidebar-resize-indicator-space: 2px;
     --page-padding: 15px;
     --content-max-width: 750px;
     --menu-bar-height: 50px;
+    --mono-font: "Source Code Pro", Consolas, "Ubuntu Mono", Menlo, "DejaVu Sans Mono", monospace, monospace;
+    --code-font-size: 0.875em; /* please adjust the ace font size accordingly in editor.js */
 }
 
 /* Themes */
@@ -36,6 +41,8 @@
     --quote-bg: hsl(226, 15%, 17%);
     --quote-border: hsl(226, 15%, 22%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(210, 25%, 13%);
     --table-header-bg: hsl(210, 25%, 28%);
     --table-alternate-bg: hsl(210, 25%, 11%);
@@ -48,6 +55,15 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #252932;
     --search-mark-bg: #e3b171;
+
+    --color-scheme: dark;
+
+    /* Same as `--icons` */
+    --copy-button-filter: invert(45%) sepia(6%) saturate(621%) hue-rotate(198deg) brightness(99%) contrast(85%);
+    /* Same as `--sidebar-active` */
+    --copy-button-filter-hover: invert(68%) sepia(55%) saturate(531%) hue-rotate(341deg) brightness(104%) contrast(101%);
+
+    --footnote-highlight: #2668a6;
 }
 
 .coal {
@@ -76,6 +92,8 @@
     --quote-bg: hsl(234, 21%, 18%);
     --quote-border: hsl(234, 21%, 23%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(200, 7%, 13%);
     --table-header-bg: hsl(200, 7%, 28%);
     --table-alternate-bg: hsl(200, 7%, 11%);
@@ -88,9 +106,18 @@
     --searchresults-border-color: #98a3ad;
     --searchresults-li-bg: #2b2b2f;
     --search-mark-bg: #355c7d;
+
+    --color-scheme: dark;
+
+    /* Same as `--icons` */
+    --copy-button-filter: invert(26%) sepia(8%) saturate(575%) hue-rotate(169deg) brightness(87%) contrast(82%);
+    /* Same as `--sidebar-active` */
+    --copy-button-filter-hover: invert(36%) sepia(70%) saturate(503%) hue-rotate(167deg) brightness(98%) contrast(89%);
+
+    --footnote-highlight: #4079ae;
 }
 
-.light {
+.light, html:not(.js) {
     --bg: hsl(0, 0%, 100%);
     --fg: hsl(0, 0%, 0%);
 
@@ -116,6 +143,8 @@
     --quote-bg: hsl(197, 37%, 96%);
     --quote-border: hsl(197, 37%, 91%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(0, 0%, 95%);
     --table-header-bg: hsl(0, 0%, 80%);
     --table-alternate-bg: hsl(0, 0%, 97%);
@@ -128,6 +157,15 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #e4f2fe;
     --search-mark-bg: #a2cff5;
+
+    --color-scheme: light;
+
+    /* Same as `--icons` */
+    --copy-button-filter: invert(45.49%);
+    /* Same as `--sidebar-active` */
+    --copy-button-filter-hover: invert(14%) sepia(93%) saturate(4250%) hue-rotate(243deg) brightness(99%) contrast(130%);
+
+    --footnote-highlight: #7e7eff;
 }
 
 .navy {
@@ -156,6 +194,8 @@
     --quote-bg: hsl(226, 15%, 17%);
     --quote-border: hsl(226, 15%, 22%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(226, 23%, 16%);
     --table-header-bg: hsl(226, 23%, 31%);
     --table-alternate-bg: hsl(226, 23%, 14%);
@@ -168,6 +208,15 @@
     --searchresults-border-color: #5c5c68;
     --searchresults-li-bg: #242430;
     --search-mark-bg: #a2cff5;
+
+    --color-scheme: dark;
+
+    /* Same as `--icons` */
+    --copy-button-filter: invert(51%) sepia(10%) saturate(393%) hue-rotate(198deg) brightness(86%) contrast(87%);
+    /* Same as `--sidebar-active` */
+    --copy-button-filter-hover: invert(46%) sepia(20%) saturate(1537%) hue-rotate(156deg) brightness(85%) contrast(90%);
+
+    --footnote-highlight: #4079ae;
 }
 
 .rust {
@@ -196,6 +245,8 @@
     --quote-bg: hsl(60, 5%, 75%);
     --quote-border: hsl(60, 5%, 70%);
 
+    --warning-border: #ff8e00;
+
     --table-border-color: hsl(60, 9%, 82%);
     --table-header-bg: #b3a497;
     --table-alternate-bg: hsl(60, 9%, 84%);
@@ -208,10 +259,17 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #dec2a2;
     --search-mark-bg: #e69f67;
+
+    /* Same as `--icons` */
+    --copy-button-filter: invert(51%) sepia(10%) saturate(393%) hue-rotate(198deg) brightness(86%) contrast(87%);
+    /* Same as `--sidebar-active` */
+    --copy-button-filter-hover: invert(77%) sepia(16%) saturate(1798%) hue-rotate(328deg) brightness(98%) contrast(83%);
+
+    --footnote-highlight: #d3a17a;
 }
 
 @media (prefers-color-scheme: dark) {
-    .light.no-js {
+    html:not(.js) {
         --bg: hsl(200, 7%, 8%);
         --fg: #98a3ad;
 
@@ -237,6 +295,8 @@
         --quote-bg: hsl(234, 21%, 18%);
         --quote-border: hsl(234, 21%, 23%);
 
+        --warning-border: #ff8e00;
+
         --table-border-color: hsl(200, 7%, 13%);
         --table-header-bg: hsl(200, 7%, 28%);
         --table-alternate-bg: hsl(200, 7%, 11%);
@@ -249,5 +309,12 @@
         --searchresults-border-color: #98a3ad;
         --searchresults-li-bg: #2b2b2f;
         --search-mark-bg: #355c7d;
+
+        --color-scheme: dark;
+
+        /* Same as `--icons` */
+        --copy-button-filter: invert(26%) sepia(8%) saturate(575%) hue-rotate(169deg) brightness(87%) contrast(82%);
+        /* Same as `--sidebar-active` */
+        --copy-button-filter-hover: invert(36%) sepia(70%) saturate(503%) hue-rotate(167deg) brightness(98%) contrast(89%);
     }
 }

src/front-end/fonts/fonts.css

@@ -7,7 +7,7 @@
   font-style: normal;
   font-weight: 300;
   src: local('Open Sans Light'), local('OpenSans-Light'),
-       url('open-sans-v17-all-charsets-300.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-300.woff2" }}') format('woff2');
 }
 
 /* open-sans-300italic - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -16,7 +16,7 @@
   font-style: italic;
   font-weight: 300;
   src: local('Open Sans Light Italic'), local('OpenSans-LightItalic'),
-       url('open-sans-v17-all-charsets-300italic.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-300italic.woff2" }}') format('woff2');
 }
 
 /* open-sans-regular - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -25,7 +25,7 @@
   font-style: normal;
   font-weight: 400;
   src: local('Open Sans Regular'), local('OpenSans-Regular'),
-       url('open-sans-v17-all-charsets-regular.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-regular.woff2" }}') format('woff2');
 }
 
 /* open-sans-italic - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -34,7 +34,7 @@
   font-style: italic;
   font-weight: 400;
   src: local('Open Sans Italic'), local('OpenSans-Italic'),
-       url('open-sans-v17-all-charsets-italic.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-italic.woff2" }}') format('woff2');
 }
 
 /* open-sans-600 - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -43,7 +43,7 @@
   font-style: normal;
   font-weight: 600;
   src: local('Open Sans SemiBold'), local('OpenSans-SemiBold'),
-       url('open-sans-v17-all-charsets-600.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-600.woff2" }}') format('woff2');
 }
 
 /* open-sans-600italic - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -52,7 +52,7 @@
   font-style: italic;
   font-weight: 600;
   src: local('Open Sans SemiBold Italic'), local('OpenSans-SemiBoldItalic'),
-       url('open-sans-v17-all-charsets-600italic.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-600italic.woff2" }}') format('woff2');
 }
 
 /* open-sans-700 - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -61,7 +61,7 @@
   font-style: normal;
   font-weight: 700;
   src: local('Open Sans Bold'), local('OpenSans-Bold'),
-       url('open-sans-v17-all-charsets-700.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-700.woff2" }}') format('woff2');
 }
 
 /* open-sans-700italic - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -70,7 +70,7 @@
   font-style: italic;
   font-weight: 700;
   src: local('Open Sans Bold Italic'), local('OpenSans-BoldItalic'),
-       url('open-sans-v17-all-charsets-700italic.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-700italic.woff2" }}') format('woff2');
 }
 
 /* open-sans-800 - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -79,7 +79,7 @@
   font-style: normal;
   font-weight: 800;
   src: local('Open Sans ExtraBold'), local('OpenSans-ExtraBold'),
-       url('open-sans-v17-all-charsets-800.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-800.woff2" }}') format('woff2');
 }
 
 /* open-sans-800italic - latin_vietnamese_latin-ext_greek-ext_greek_cyrillic-ext_cyrillic */
@@ -88,7 +88,7 @@
   font-style: italic;
   font-weight: 800;
   src: local('Open Sans ExtraBold Italic'), local('OpenSans-ExtraBoldItalic'),
-       url('open-sans-v17-all-charsets-800italic.woff2') format('woff2');
+       url('{{ resource "fonts/open-sans-v17-all-charsets-800italic.woff2" }}') format('woff2');
 }
 
 /* source-code-pro-500 - latin_vietnamese_latin-ext_greek_cyrillic-ext_cyrillic */
@@ -96,5 +96,5 @@
   font-family: 'Source Code Pro';
   font-style: normal;
   font-weight: 500;
-  src: url('source-code-pro-v11-all-charsets-500.woff2') format('woff2');
+  src: url('{{ resource "fonts/source-code-pro-v11-all-charsets-500.woff2" }}') format('woff2');
 }

src/front-end/js/book.js

@@ -0,0 +1,769 @@
+'use strict';
+
+/* global default_theme, default_dark_theme, default_light_theme, hljs, ClipboardJS */
+
+// Fix back button cache problem
+window.onunload = function() { };
+
+// Global variable, shared between modules
+function playground_text(playground, hidden = true) {
+    const code_block = playground.querySelector('code');
+
+    if (window.ace && code_block.classList.contains('editable')) {
+        const editor = window.ace.edit(code_block);
+        return editor.getValue();
+    } else if (hidden) {
+        return code_block.textContent;
+    } else {
+        return code_block.innerText;
+    }
+}
+
+(function codeSnippets() {
+    function fetch_with_timeout(url, options, timeout = 6000) {
+        return Promise.race([
+            fetch(url, options),
+            new Promise((_, reject) => setTimeout(() => reject(new Error('timeout')), timeout)),
+        ]);
+    }
+
+    const playgrounds = Array.from(document.querySelectorAll('.playground'));
+    if (playgrounds.length > 0) {
+        fetch_with_timeout('https://play.rust-lang.org/meta/crates', {
+            headers: {
+                'Content-Type': 'application/json',
+            },
+            method: 'POST',
+            mode: 'cors',
+        })
+            .then(response => response.json())
+            .then(response => {
+            // get list of crates available in the rust playground
+                const playground_crates = response.crates.map(item => item['id']);
+                playgrounds.forEach(block => handle_crate_list_update(block, playground_crates));
+            });
+    }
+
+    function handle_crate_list_update(playground_block, playground_crates) {
+        // update the play buttons after receiving the response
+        update_play_button(playground_block, playground_crates);
+
+        // and install on change listener to dynamically update ACE editors
+        if (window.ace) {
+            const code_block = playground_block.querySelector('code');
+            if (code_block.classList.contains('editable')) {
+                const editor = window.ace.edit(code_block);
+                editor.addEventListener('change', () => {
+                    update_play_button(playground_block, playground_crates);
+                });
+                // add Ctrl-Enter command to execute rust code
+                editor.commands.addCommand({
+                    name: 'run',
+                    bindKey: {
+                        win: 'Ctrl-Enter',
+                        mac: 'Ctrl-Enter',
+                    },
+                    exec: _editor => run_rust_code(playground_block),
+                });
+            }
+        }
+    }
+
+    // updates the visibility of play button based on `no_run` class and
+    // used crates vs ones available on https://play.rust-lang.org
+    function update_play_button(pre_block, playground_crates) {
+        const play_button = pre_block.querySelector('.play-button');
+
+        // skip if code is `no_run`
+        if (pre_block.querySelector('code').classList.contains('no_run')) {
+            play_button.classList.add('hidden');
+            return;
+        }
+
+        // get list of `extern crate`'s from snippet
+        const txt = playground_text(pre_block);
+        const re = /extern\s+crate\s+([a-zA-Z_0-9]+)\s*;/g;
+        const snippet_crates = [];
+        let item;
+        // eslint-disable-next-line no-cond-assign
+        while (item = re.exec(txt)) {
+            snippet_crates.push(item[1]);
+        }
+
+        // check if all used crates are available on play.rust-lang.org
+        const all_available = snippet_crates.every(function(elem) {
+            return playground_crates.indexOf(elem) > -1;
+        });
+
+        if (all_available) {
+            play_button.classList.remove('hidden');
+        } else {
+            play_button.classList.add('hidden');
+        }
+    }
+
+    function run_rust_code(code_block) {
+        let result_block = code_block.querySelector('.result');
+        if (!result_block) {
+            result_block = document.createElement('code');
+            result_block.className = 'result hljs language-bash';
+
+            code_block.append(result_block);
+        }
+
+        const text = playground_text(code_block);
+        const classes = code_block.querySelector('code').classList;
+        let edition = '2015';
+        classes.forEach(className => {
+            if (className.startsWith('edition')) {
+                edition = className.slice(7);
+            }
+        });
+        const params = {
+            version: 'stable',
+            optimize: '0',
+            code: text,
+            edition: edition,
+        };
+
+        if (text.indexOf('#![feature') !== -1) {
+            params.version = 'nightly';
+        }
+
+        result_block.innerText = 'Running...';
+
+        fetch_with_timeout('https://play.rust-lang.org/evaluate.json', {
+            headers: {
+                'Content-Type': 'application/json',
+            },
+            method: 'POST',
+            mode: 'cors',
+            body: JSON.stringify(params),
+        })
+            .then(response => response.json())
+            .then(response => {
+                if (response.result.trim() === '') {
+                    result_block.innerText = 'No output';
+                    result_block.classList.add('result-no-output');
+                } else {
+                    result_block.innerText = response.result;
+                    result_block.classList.remove('result-no-output');
+                }
+            })
+            .catch(error => result_block.innerText = 'Playground Communication: ' + error.message);
+    }
+
+    // Syntax highlighting Configuration
+    hljs.configure({
+        tabReplace: '    ', // 4 spaces
+        languages: [], // Languages used for auto-detection
+    });
+
+    const code_nodes = Array
+        .from(document.querySelectorAll('code'))
+        // Don't highlight `inline code` blocks in headers.
+        .filter(function(node) {
+            return !node.parentElement.classList.contains('header');
+        });
+
+    if (window.ace) {
+        // language-rust class needs to be removed for editable
+        // blocks or highlightjs will capture events
+        code_nodes
+            .filter(function(node) {
+                return node.classList.contains('editable');
+            })
+            .forEach(function(block) {
+                block.classList.remove('language-rust');
+            });
+
+        code_nodes
+            .filter(function(node) {
+                return !node.classList.contains('editable');
+            })
+            .forEach(function(block) {
+                hljs.highlightBlock(block);
+            });
+    } else {
+        code_nodes.forEach(function(block) {
+            hljs.highlightBlock(block);
+        });
+    }
+
+    // Adding the hljs class gives code blocks the color css
+    // even if highlighting doesn't apply
+    code_nodes.forEach(function(block) {
+        block.classList.add('hljs');
+    });
+
+    Array.from(document.querySelectorAll('code.hljs')).forEach(function(block) {
+
+        const lines = Array.from(block.querySelectorAll('.boring'));
+        // If no lines were hidden, return
+        if (!lines.length) {
+            return;
+        }
+        block.classList.add('hide-boring');
+
+        const buttons = document.createElement('div');
+        buttons.className = 'buttons';
+        buttons.innerHTML = '<button class="fa fa-eye" title="Show hidden lines" \
+aria-label="Show hidden lines"></button>';
+
+        // add expand button
+        const pre_block = block.parentNode;
+        pre_block.insertBefore(buttons, pre_block.firstChild);
+
+        pre_block.querySelector('.buttons').addEventListener('click', function(e) {
+            if (e.target.classList.contains('fa-eye')) {
+                e.target.classList.remove('fa-eye');
+                e.target.classList.add('fa-eye-slash');
+                e.target.title = 'Hide lines';
+                e.target.setAttribute('aria-label', e.target.title);
+
+                block.classList.remove('hide-boring');
+            } else if (e.target.classList.contains('fa-eye-slash')) {
+                e.target.classList.remove('fa-eye-slash');
+                e.target.classList.add('fa-eye');
+                e.target.title = 'Show hidden lines';
+                e.target.setAttribute('aria-label', e.target.title);
+
+                block.classList.add('hide-boring');
+            }
+        });
+    });
+
+    if (window.playground_copyable) {
+        Array.from(document.querySelectorAll('pre code')).forEach(function(block) {
+            const pre_block = block.parentNode;
+            if (!pre_block.classList.contains('playground')) {
+                let buttons = pre_block.querySelector('.buttons');
+                if (!buttons) {
+                    buttons = document.createElement('div');
+                    buttons.className = 'buttons';
+                    pre_block.insertBefore(buttons, pre_block.firstChild);
+                }
+
+                const clipButton = document.createElement('button');
+                clipButton.className = 'clip-button';
+                clipButton.title = 'Copy to clipboard';
+                clipButton.setAttribute('aria-label', clipButton.title);
+                clipButton.innerHTML = '<i class="tooltiptext"></i>';
+
+                buttons.insertBefore(clipButton, buttons.firstChild);
+            }
+        });
+    }
+
+    // Process playground code blocks
+    Array.from(document.querySelectorAll('.playground')).forEach(function(pre_block) {
+        // Add play button
+        let buttons = pre_block.querySelector('.buttons');
+        if (!buttons) {
+            buttons = document.createElement('div');
+            buttons.className = 'buttons';
+            pre_block.insertBefore(buttons, pre_block.firstChild);
+        }
+
+        const runCodeButton = document.createElement('button');
+        runCodeButton.className = 'fa fa-play play-button';
+        runCodeButton.hidden = true;
+        runCodeButton.title = 'Run this code';
+        runCodeButton.setAttribute('aria-label', runCodeButton.title);
+
+        buttons.insertBefore(runCodeButton, buttons.firstChild);
+        runCodeButton.addEventListener('click', () => {
+            run_rust_code(pre_block);
+        });
+
+        if (window.playground_copyable) {
+            const copyCodeClipboardButton = document.createElement('button');
+            copyCodeClipboardButton.className = 'clip-button';
+            copyCodeClipboardButton.innerHTML = '<i class="tooltiptext"></i>';
+            copyCodeClipboardButton.title = 'Copy to clipboard';
+            copyCodeClipboardButton.setAttribute('aria-label', copyCodeClipboardButton.title);
+
+            buttons.insertBefore(copyCodeClipboardButton, buttons.firstChild);
+        }
+
+        const code_block = pre_block.querySelector('code');
+        if (window.ace && code_block.classList.contains('editable')) {
+            const undoChangesButton = document.createElement('button');
+            undoChangesButton.className = 'fa fa-history reset-button';
+            undoChangesButton.title = 'Undo changes';
+            undoChangesButton.setAttribute('aria-label', undoChangesButton.title);
+
+            buttons.insertBefore(undoChangesButton, buttons.firstChild);
+
+            undoChangesButton.addEventListener('click', function() {
+                const editor = window.ace.edit(code_block);
+                editor.setValue(editor.originalCode);
+                editor.clearSelection();
+            });
+        }
+    });
+})();
+
+(function themes() {
+    const html = document.querySelector('html');
+    const themeToggleButton = document.getElementById('theme-toggle');
+    const themePopup = document.getElementById('theme-list');
+    const themeColorMetaTag = document.querySelector('meta[name="theme-color"]');
+    const themeIds = [];
+    themePopup.querySelectorAll('button.theme').forEach(function(el) {
+        themeIds.push(el.id);
+    });
+    const stylesheets = {
+        ayuHighlight: document.querySelector('#ayu-highlight-css'),
+        tomorrowNight: document.querySelector('#tomorrow-night-css'),
+        highlight: document.querySelector('#highlight-css'),
+    };
+
+    function showThemes() {
+        themePopup.style.display = 'block';
+        themeToggleButton.setAttribute('aria-expanded', true);
+        themePopup.querySelector('button#' + get_theme()).focus();
+    }
+
+    function updateThemeSelected() {
+        themePopup.querySelectorAll('.theme-selected').forEach(function(el) {
+            el.classList.remove('theme-selected');
+        });
+        const selected = get_saved_theme() ?? 'default_theme';
+        let element = themePopup.querySelector('button#' + selected);
+        if (element === null) {
+            // Fall back in case there is no "Default" item.
+            element = themePopup.querySelector('button#' + get_theme());
+        }
+        element.classList.add('theme-selected');
+    }
+
+    function hideThemes() {
+        themePopup.style.display = 'none';
+        themeToggleButton.setAttribute('aria-expanded', false);
+        themeToggleButton.focus();
+    }
+
+    function get_saved_theme() {
+        let theme = null;
+        try {
+            theme = localStorage.getItem('mdbook-theme');
+        } catch (e) {
+            // ignore error.
+        }
+        return theme;
+    }
+
+    function delete_saved_theme() {
+        localStorage.removeItem('mdbook-theme');
+    }
+
+    function get_theme() {
+        const theme = get_saved_theme();
+        if (theme === null || theme === undefined || !themeIds.includes(theme)) {
+            if (typeof default_dark_theme === 'undefined') {
+                // A customized index.hbs might not define this, so fall back to
+                // old behavior of determining the default on page load.
+                return default_theme;
+            }
+            return window.matchMedia('(prefers-color-scheme: dark)').matches
+                ? default_dark_theme
+                : default_light_theme;
+        } else {
+            return theme;
+        }
+    }
+
+    let previousTheme = default_theme;
+    function set_theme(theme, store = true) {
+        let ace_theme;
+
+        if (theme === 'coal' || theme === 'navy') {
+            stylesheets.ayuHighlight.disabled = true;
+            stylesheets.tomorrowNight.disabled = false;
+            stylesheets.highlight.disabled = true;
+
+            ace_theme = 'ace/theme/tomorrow_night';
+        } else if (theme === 'ayu') {
+            stylesheets.ayuHighlight.disabled = false;
+            stylesheets.tomorrowNight.disabled = true;
+            stylesheets.highlight.disabled = true;
+            ace_theme = 'ace/theme/tomorrow_night';
+        } else {
+            stylesheets.ayuHighlight.disabled = true;
+            stylesheets.tomorrowNight.disabled = true;
+            stylesheets.highlight.disabled = false;
+            ace_theme = 'ace/theme/dawn';
+        }
+
+        setTimeout(function() {
+            themeColorMetaTag.content = getComputedStyle(document.documentElement).backgroundColor;
+        }, 1);
+
+        if (window.ace && window.editors) {
+            window.editors.forEach(function(editor) {
+                editor.setTheme(ace_theme);
+            });
+        }
+
+        if (store) {
+            try {
+                localStorage.setItem('mdbook-theme', theme);
+            } catch (e) {
+                // ignore error.
+            }
+        }
+
+        html.classList.remove(previousTheme);
+        html.classList.add(theme);
+        previousTheme = theme;
+        updateThemeSelected();
+    }
+
+    const query = window.matchMedia('(prefers-color-scheme: dark)');
+    query.onchange = function() {
+        set_theme(get_theme(), false);
+    };
+
+    // Set theme.
+    set_theme(get_theme(), false);
+
+    themeToggleButton.addEventListener('click', function() {
+        if (themePopup.style.display === 'block') {
+            hideThemes();
+        } else {
+            showThemes();
+        }
+    });
+
+    themePopup.addEventListener('click', function(e) {
+        let theme;
+        if (e.target.className === 'theme') {
+            theme = e.target.id;
+        } else if (e.target.parentElement.className === 'theme') {
+            theme = e.target.parentElement.id;
+        } else {
+            return;
+        }
+        if (theme === 'default_theme' || theme === null) {
+            delete_saved_theme();
+            set_theme(get_theme(), false);
+        } else {
+            set_theme(theme);
+        }
+    });
+
+    themePopup.addEventListener('focusout', function(e) {
+        // e.relatedTarget is null in Safari and Firefox on macOS (see workaround below)
+        if (!!e.relatedTarget &&
+            !themeToggleButton.contains(e.relatedTarget) &&
+            !themePopup.contains(e.relatedTarget)
+        ) {
+            hideThemes();
+        }
+    });
+
+    // Should not be needed, but it works around an issue on macOS & iOS:
+    // https://github.com/rust-lang/mdBook/issues/628
+    document.addEventListener('click', function(e) {
+        if (themePopup.style.display === 'block' &&
+            !themeToggleButton.contains(e.target) &&
+            !themePopup.contains(e.target)
+        ) {
+            hideThemes();
+        }
+    });
+
+    document.addEventListener('keydown', function(e) {
+        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) {
+            return;
+        }
+        if (!themePopup.contains(e.target)) {
+            return;
+        }
+
+        let li;
+        switch (e.key) {
+        case 'Escape':
+            e.preventDefault();
+            hideThemes();
+            break;
+        case 'ArrowUp':
+            e.preventDefault();
+            li = document.activeElement.parentElement;
+            if (li && li.previousElementSibling) {
+                li.previousElementSibling.querySelector('button').focus();
+            }
+            break;
+        case 'ArrowDown':
+            e.preventDefault();
+            li = document.activeElement.parentElement;
+            if (li && li.nextElementSibling) {
+                li.nextElementSibling.querySelector('button').focus();
+            }
+            break;
+        case 'Home':
+            e.preventDefault();
+            themePopup.querySelector('li:first-child button').focus();
+            break;
+        case 'End':
+            e.preventDefault();
+            themePopup.querySelector('li:last-child button').focus();
+            break;
+        }
+    });
+})();
+
+(function sidebar() {
+    const body = document.querySelector('body');
+    const sidebar = document.getElementById('sidebar');
+    const sidebarLinks = document.querySelectorAll('#sidebar a');
+    const sidebarToggleButton = document.getElementById('sidebar-toggle');
+    const sidebarToggleAnchor = document.getElementById('sidebar-toggle-anchor');
+    const sidebarResizeHandle = document.getElementById('sidebar-resize-handle');
+    let firstContact = null;
+
+    function showSidebar() {
+        body.classList.remove('sidebar-hidden');
+        body.classList.add('sidebar-visible');
+        Array.from(sidebarLinks).forEach(function(link) {
+            link.setAttribute('tabIndex', 0);
+        });
+        sidebarToggleButton.setAttribute('aria-expanded', true);
+        sidebar.setAttribute('aria-hidden', false);
+        try {
+            localStorage.setItem('mdbook-sidebar', 'visible');
+        } catch (e) {
+            // Ignore error.
+        }
+    }
+
+    function hideSidebar() {
+        body.classList.remove('sidebar-visible');
+        body.classList.add('sidebar-hidden');
+        Array.from(sidebarLinks).forEach(function(link) {
+            link.setAttribute('tabIndex', -1);
+        });
+        sidebarToggleButton.setAttribute('aria-expanded', false);
+        sidebar.setAttribute('aria-hidden', true);
+        try {
+            localStorage.setItem('mdbook-sidebar', 'hidden');
+        } catch (e) {
+            // Ignore error.
+        }
+    }
+
+    // Toggle sidebar
+    sidebarToggleAnchor.addEventListener('change', function sidebarToggle() {
+        if (sidebarToggleAnchor.checked) {
+            const current_width = parseInt(
+                document.documentElement.style.getPropertyValue('--sidebar-target-width'), 10);
+            if (current_width < 150) {
+                document.documentElement.style.setProperty('--sidebar-target-width', '150px');
+            }
+            showSidebar();
+        } else {
+            hideSidebar();
+        }
+    });
+
+    sidebarResizeHandle.addEventListener('mousedown', initResize, false);
+
+    function initResize() {
+        window.addEventListener('mousemove', resize, false);
+        window.addEventListener('mouseup', stopResize, false);
+        body.classList.add('sidebar-resizing');
+    }
+    function resize(e) {
+        let pos = e.clientX - sidebar.offsetLeft;
+        if (pos < 20) {
+            hideSidebar();
+        } else {
+            if (body.classList.contains('sidebar-hidden')) {
+                showSidebar();
+            }
+            pos = Math.min(pos, window.innerWidth - 100);
+            document.documentElement.style.setProperty('--sidebar-target-width', pos + 'px');
+        }
+    }
+    //on mouseup remove windows functions mousemove & mouseup
+    function stopResize() {
+        body.classList.remove('sidebar-resizing');
+        window.removeEventListener('mousemove', resize, false);
+        window.removeEventListener('mouseup', stopResize, false);
+    }
+
+    document.addEventListener('touchstart', function(e) {
+        firstContact = {
+            x: e.touches[0].clientX,
+            time: Date.now(),
+        };
+    }, { passive: true });
+
+    document.addEventListener('touchmove', function(e) {
+        if (!firstContact) {
+            return;
+        }
+
+        const curX = e.touches[0].clientX;
+        const xDiff = curX - firstContact.x,
+            tDiff = Date.now() - firstContact.time;
+
+        if (tDiff < 250 && Math.abs(xDiff) >= 150) {
+            if (xDiff >= 0 && firstContact.x < Math.min(document.body.clientWidth * 0.25, 300)) {
+                showSidebar();
+            } else if (xDiff < 0 && curX < 300) {
+                hideSidebar();
+            }
+
+            firstContact = null;
+        }
+    }, { passive: true });
+})();
+
+(function chapterNavigation() {
+    document.addEventListener('keydown', function(e) {
+        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) {
+            return;
+        }
+        if (window.search && window.search.hasFocus()) {
+            return;
+        }
+        const html = document.querySelector('html');
+
+        function next() {
+            const nextButton = document.querySelector('.nav-chapters.next');
+            if (nextButton) {
+                window.location.href = nextButton.href;
+            }
+        }
+        function prev() {
+            const previousButton = document.querySelector('.nav-chapters.previous');
+            if (previousButton) {
+                window.location.href = previousButton.href;
+            }
+        }
+        switch (e.key) {
+        case 'ArrowRight':
+            e.preventDefault();
+            if (html.dir === 'rtl') {
+                prev();
+            } else {
+                next();
+            }
+            break;
+        case 'ArrowLeft':
+            e.preventDefault();
+            if (html.dir === 'rtl') {
+                next();
+            } else {
+                prev();
+            }
+            break;
+        }
+    });
+})();
+
+(function clipboard() {
+    const clipButtons = document.querySelectorAll('.clip-button');
+
+    function hideTooltip(elem) {
+        elem.firstChild.innerText = '';
+        elem.className = 'clip-button';
+    }
+
+    function showTooltip(elem, msg) {
+        elem.firstChild.innerText = msg;
+        elem.className = 'clip-button tooltipped';
+    }
+
+    const clipboardSnippets = new ClipboardJS('.clip-button', {
+        text: function(trigger) {
+            hideTooltip(trigger);
+            const playground = trigger.closest('pre');
+            return playground_text(playground, false);
+        },
+    });
+
+    Array.from(clipButtons).forEach(function(clipButton) {
+        clipButton.addEventListener('mouseout', function(e) {
+            hideTooltip(e.currentTarget);
+        });
+    });
+
+    clipboardSnippets.on('success', function(e) {
+        e.clearSelection();
+        showTooltip(e.trigger, 'Copied!');
+    });
+
+    clipboardSnippets.on('error', function(e) {
+        showTooltip(e.trigger, 'Clipboard error!');
+    });
+})();
+
+(function scrollToTop() {
+    const menuTitle = document.querySelector('.menu-title');
+
+    menuTitle.addEventListener('click', function() {
+        document.scrollingElement.scrollTo({ top: 0, behavior: 'smooth' });
+    });
+})();
+
+(function controllMenu() {
+    const menu = document.getElementById('menu-bar');
+
+    (function controllPosition() {
+        let scrollTop = document.scrollingElement.scrollTop;
+        let prevScrollTop = scrollTop;
+        const minMenuY = -menu.clientHeight - 50;
+        // When the script loads, the page can be at any scroll (e.g. if you reforesh it).
+        menu.style.top = scrollTop + 'px';
+        // Same as parseInt(menu.style.top.slice(0, -2), but faster
+        let topCache = menu.style.top.slice(0, -2);
+        menu.classList.remove('sticky');
+        let stickyCache = false; // Same as menu.classList.contains('sticky'), but faster
+        document.addEventListener('scroll', function() {
+            scrollTop = Math.max(document.scrollingElement.scrollTop, 0);
+            // `null` means that it doesn't need to be updated
+            let nextSticky = null;
+            let nextTop = null;
+            const scrollDown = scrollTop > prevScrollTop;
+            const menuPosAbsoluteY = topCache - scrollTop;
+            if (scrollDown) {
+                nextSticky = false;
+                if (menuPosAbsoluteY > 0) {
+                    nextTop = prevScrollTop;
+                }
+            } else {
+                if (menuPosAbsoluteY > 0) {
+                    nextSticky = true;
+                } else if (menuPosAbsoluteY < minMenuY) {
+                    nextTop = prevScrollTop + minMenuY;
+                }
+            }
+            if (nextSticky === true && stickyCache === false) {
+                menu.classList.add('sticky');
+                stickyCache = true;
+            } else if (nextSticky === false && stickyCache === true) {
+                menu.classList.remove('sticky');
+                stickyCache = false;
+            }
+            if (nextTop !== null) {
+                menu.style.top = nextTop + 'px';
+                topCache = nextTop;
+            }
+            prevScrollTop = scrollTop;
+        }, { passive: true });
+    })();
+    (function controllBorder() {
+        function updateBorder() {
+            if (menu.offsetTop === 0) {
+                menu.classList.remove('bordered');
+            } else {
+                menu.classList.add('bordered');
+            }
+        }
+        updateBorder();
+        document.addEventListener('scroll', updateBorder, { passive: true });
+    })();
+})();

src/front-end/mod.rs

@@ -9,34 +9,35 @@ pub mod searcher;
 
 use std::fs::File;
 use std::io::Read;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use crate::errors::*;
-
-pub static INDEX: &[u8] = include_bytes!("index.hbs");
-pub static HEAD: &[u8] = include_bytes!("head.hbs");
-pub static REDIRECT: &[u8] = include_bytes!("redirect.hbs");
-pub static HEADER: &[u8] = include_bytes!("header.hbs");
+use log::warn;
+pub static INDEX: &[u8] = include_bytes!("templates/index.hbs");
+pub static HEAD: &[u8] = include_bytes!("templates/head.hbs");
+pub static REDIRECT: &[u8] = include_bytes!("templates/redirect.hbs");
+pub static HEADER: &[u8] = include_bytes!("templates/header.hbs");
+pub static TOC_JS: &[u8] = include_bytes!("templates/toc.js.hbs");
+pub static TOC_HTML: &[u8] = include_bytes!("templates/toc.html.hbs");
 pub static CHROME_CSS: &[u8] = include_bytes!("css/chrome.css");
 pub static GENERAL_CSS: &[u8] = include_bytes!("css/general.css");
 pub static PRINT_CSS: &[u8] = include_bytes!("css/print.css");
 pub static VARIABLES_CSS: &[u8] = include_bytes!("css/variables.css");
-pub static FAVICON_PNG: &[u8] = include_bytes!("favicon.png");
-pub static FAVICON_SVG: &[u8] = include_bytes!("favicon.svg");
-pub static JS: &[u8] = include_bytes!("book.js");
-pub static HIGHLIGHT_JS: &[u8] = include_bytes!("highlight.js");
-pub static TOMORROW_NIGHT_CSS: &[u8] = include_bytes!("tomorrow-night.css");
-pub static HIGHLIGHT_CSS: &[u8] = include_bytes!("highlight.css");
-pub static AYU_HIGHLIGHT_CSS: &[u8] = include_bytes!("ayu-highlight.css");
-pub static CLIPBOARD_JS: &[u8] = include_bytes!("clipboard.min.js");
-pub static FONT_AWESOME: &[u8] = include_bytes!("FontAwesome/css/font-awesome.min.css");
-pub static FONT_AWESOME_EOT: &[u8] = include_bytes!("FontAwesome/fonts/fontawesome-webfont.eot");
-pub static FONT_AWESOME_SVG: &[u8] = include_bytes!("FontAwesome/fonts/fontawesome-webfont.svg");
-pub static FONT_AWESOME_TTF: &[u8] = include_bytes!("FontAwesome/fonts/fontawesome-webfont.ttf");
-pub static FONT_AWESOME_WOFF: &[u8] = include_bytes!("FontAwesome/fonts/fontawesome-webfont.woff");
-pub static FONT_AWESOME_WOFF2: &[u8] =
-    include_bytes!("FontAwesome/fonts/fontawesome-webfont.woff2");
-pub static FONT_AWESOME_OTF: &[u8] = include_bytes!("FontAwesome/fonts/FontAwesome.otf");
+pub static FAVICON_PNG: &[u8] = include_bytes!("images/favicon.png");
+pub static FAVICON_SVG: &[u8] = include_bytes!("images/favicon.svg");
+pub static JS: &[u8] = include_bytes!("js/book.js");
+pub static HIGHLIGHT_JS: &[u8] = include_bytes!("js/highlight.js");
+pub static TOMORROW_NIGHT_CSS: &[u8] = include_bytes!("css/tomorrow-night.css");
+pub static HIGHLIGHT_CSS: &[u8] = include_bytes!("css/highlight.css");
+pub static AYU_HIGHLIGHT_CSS: &[u8] = include_bytes!("css/ayu-highlight.css");
+pub static CLIPBOARD_JS: &[u8] = include_bytes!("js/clipboard.min.js");
+pub static FONT_AWESOME: &[u8] = include_bytes!("css/font-awesome.min.css");
+pub static FONT_AWESOME_EOT: &[u8] = include_bytes!("fonts/fontawesome-webfont.eot");
+pub static FONT_AWESOME_SVG: &[u8] = include_bytes!("fonts/fontawesome-webfont.svg");
+pub static FONT_AWESOME_TTF: &[u8] = include_bytes!("fonts/fontawesome-webfont.ttf");
+pub static FONT_AWESOME_WOFF: &[u8] = include_bytes!("fonts/fontawesome-webfont.woff");
+pub static FONT_AWESOME_WOFF2: &[u8] = include_bytes!("fonts/fontawesome-webfont.woff2");
+pub static FONT_AWESOME_OTF: &[u8] = include_bytes!("fonts/FontAwesome.otf");
 
 /// The `Theme` struct should be used instead of the static variables because
 /// the `new()` method will look if the user has a theme directory in their
@@ -50,10 +51,14 @@ pub struct Theme {
     pub head: Vec<u8>,
     pub redirect: Vec<u8>,
     pub header: Vec<u8>,
+    pub toc_js: Vec<u8>,
+    pub toc_html: Vec<u8>,
     pub chrome_css: Vec<u8>,
     pub general_css: Vec<u8>,
     pub print_css: Vec<u8>,
     pub variables_css: Vec<u8>,
+    pub fonts_css: Option<Vec<u8>>,
+    pub font_files: Vec<PathBuf>,
     pub favicon_png: Option<Vec<u8>>,
     pub favicon_svg: Option<Vec<u8>>,
     pub js: Vec<u8>,
@@ -83,6 +88,8 @@ impl Theme {
                 (theme_dir.join("head.hbs"), &mut theme.head),
                 (theme_dir.join("redirect.hbs"), &mut theme.redirect),
                 (theme_dir.join("header.hbs"), &mut theme.header),
+                (theme_dir.join("toc.js.hbs"), &mut theme.toc_js),
+                (theme_dir.join("toc.html.hbs"), &mut theme.toc_html),
                 (theme_dir.join("book.js"), &mut theme.js),
                 (theme_dir.join("css/chrome.css"), &mut theme.chrome_css),
                 (theme_dir.join("css/general.css"), &mut theme.general_css),
@@ -104,7 +111,7 @@ impl Theme {
                 ),
             ];
 
-            let load_with_warn = |filename: &Path, dest| {
+            let load_with_warn = |filename: &Path, dest: &mut Vec<u8>| {
                 if !filename.exists() {
                     // Don't warn if the file doesn't exist.
                     return false;
@@ -121,6 +128,29 @@ impl Theme {
                 load_with_warn(&filename, dest);
             }
 
+            let fonts_dir = theme_dir.join("fonts");
+            if fonts_dir.exists() {
+                let mut fonts_css = Vec::new();
+                if load_with_warn(&fonts_dir.join("fonts.css"), &mut fonts_css) {
+                    theme.fonts_css.replace(fonts_css);
+                }
+                if let Ok(entries) = fonts_dir.read_dir() {
+                    theme.font_files = entries
+                        .filter_map(|entry| {
+                            let entry = entry.ok()?;
+                            if entry.file_name() == "fonts.css" {
+                                None
+                            } else if entry.file_type().ok()?.is_dir() {
+                                log::info!("skipping font directory {:?}", entry.path());
+                                None
+                            } else {
+                                Some(entry.path())
+                            }
+                        })
+                        .collect();
+                }
+            }
+
             // If the user overrides one favicon, but not the other, do not
             // copy the default for the other.
             let favicon_png = &mut theme.favicon_png.as_mut().unwrap();
@@ -149,10 +179,14 @@ impl Default for Theme {
             head: HEAD.to_owned(),
             redirect: REDIRECT.to_owned(),
             header: HEADER.to_owned(),
+            toc_js: TOC_JS.to_owned(),
+            toc_html: TOC_HTML.to_owned(),
             chrome_css: CHROME_CSS.to_owned(),
             general_css: GENERAL_CSS.to_owned(),
             print_css: PRINT_CSS.to_owned(),
             variables_css: VARIABLES_CSS.to_owned(),
+            fonts_css: None,
+            font_files: Vec::new(),
             favicon_png: Some(FAVICON_PNG.to_owned()),
             favicon_svg: Some(FAVICON_SVG.to_owned()),
             js: JS.to_owned(),
@@ -185,7 +219,6 @@ fn load_file_contents<P: AsRef<Path>>(filename: P, dest: &mut Vec<u8>) -> Result
 mod tests {
     use super::*;
     use std::fs;
-    use std::path::PathBuf;
     use tempfile::Builder as TempFileBuilder;
 
     #[test]
@@ -206,13 +239,15 @@ mod tests {
             "head.hbs",
             "redirect.hbs",
             "header.hbs",
+            "toc.js.hbs",
+            "toc.html.hbs",
             "favicon.png",
             "favicon.svg",
             "css/chrome.css",
-            "css/fonts.css",
             "css/general.css",
             "css/print.css",
             "css/variables.css",
+            "fonts/fonts.css",
             "book.js",
             "highlight.js",
             "tomorrow-night.css",
@@ -223,6 +258,7 @@ mod tests {
 
         let temp = TempFileBuilder::new().prefix("mdbook-").tempdir().unwrap();
         fs::create_dir(temp.path().join("css")).unwrap();
+        fs::create_dir(temp.path().join("fonts")).unwrap();
 
         // "touch" all of the special files so we have empty copies
         for file in &files {
@@ -236,10 +272,14 @@ mod tests {
             head: Vec::new(),
             redirect: Vec::new(),
             header: Vec::new(),
+            toc_js: Vec::new(),
+            toc_html: Vec::new(),
             chrome_css: Vec::new(),
             general_css: Vec::new(),
             print_css: Vec::new(),
             variables_css: Vec::new(),
+            fonts_css: Some(Vec::new()),
+            font_files: Vec::new(),
             favicon_png: Some(Vec::new()),
             favicon_svg: Some(Vec::new()),
             js: Vec::new(),