Merge pull request #2206 from ehuss/bump-version

Update to 0.4.35

.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

@@ -3,26 +3,46 @@ 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]
+        target:
+          - aarch64-unknown-linux-musl
+          - x86_64-unknown-linux-gnu
+          - x86_64-unknown-linux-musl
+          - x86_64-apple-darwin
+          - x86_64-pc-windows-msvc
+        include:
+          - target: aarch64-unknown-linux-musl
+            os: ubuntu-20.04
+          - target: x86_64-unknown-linux-gnu
+            os: ubuntu-20.04
+          - target: x86_64-unknown-linux-musl
+            os: ubuntu-20.04
+          - target: x86_64-apple-darwin
+            os: macos-latest
+          - target: x86_64-pc-windows-msvc
+            os: windows-latest
     steps:
     - uses: actions/checkout@master
-    - name: Install hub
-      run: ci/install-hub.sh ${{ matrix.os }}
-      shell: bash
     - 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
@@ -40,3 +60,14 @@ 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@master
+      - 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

@@ -1,10 +1,7 @@
 name: CI
 on:
-  # Only run when merging to master, or open/synchronize/reopen a PR.
-  push:
-    branches:
-      - master
   pull_request:
+  merge_group:
 
 jobs:
   test:
@@ -30,15 +27,15 @@ jobs:
             os: windows-latest
             rust: stable
           - build: msrv
-            os: ubuntu-latest
-            # sync MSRV with docs: guide/src/guide/installation.md
-            rust: 1.54.0
+            os: ubuntu-20.04
+            # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
+            rust: 1.66.0
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: Install Rust
       run: bash ci/install-rust.sh ${{ matrix.rust }}
     - name: Build and run tests
-      run: cargo test
+      run: cargo test --locked
     - name: Test no default
       run: cargo test --no-default-features
 
@@ -46,7 +43,24 @@ jobs:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup component add rustfmt
     - run: cargo fmt --check
+
+  # 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
+    runs-on: ubuntu-latest
+    steps:
+      - run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'
+      - name: Done
+        run: exit 0

CHANGELOG.md

@@ -1,7 +1,226 @@
 # Changelog
 
+## 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...eb82ddc](https://github.com/rust-lang/mdBook/compare/ae275ad...eb82ddc)
+[ae275ad...53055e0](https://github.com/rust-lang/mdBook/compare/ae275ad...53055e0)
 
 ### Added
 - The `serve` command now supports HEAD requests.
@@ -60,7 +279,7 @@
   [#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
@@ -116,7 +141,7 @@ 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.
 
-## Updating higlight.js
+## Updating highlight.js
 
 The following are instructions for updating [highlight.js](https://highlightjs.org/).
 
@@ -128,3 +153,23 @@ The following are instructions for updating [highlight.js](https://highlightjs.o
 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

@@ -1,67 +1,73 @@
 [package]
 name = "mdbook"
-version = "0.4.19"
+version = "0.4.35"
 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 = "1.66"
 
 [dependencies]
-anyhow = "1.0.28"
-chrono = "0.4"
-clap = { version = "3.0", features = ["cargo"] }
-clap_complete = "3.0"
-env_logger = "0.9.0"
-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 = { version = "1.0", features = ["derive"] }
-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 = "0.10.0"
+handlebars = "4.3.7"
+log = "0.4.17"
+memchr = "2.5.0"
+opener = "0.6.1"
+pulldown-cmark = { version = "0.9.3", default-features = false }
+regex = "1.8.1"
+serde = { version = "1.0.163", features = ["derive"] }
+serde_json = "1.0.96"
+shlex = "1.1.0"
+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 = "6.0.1", optional = true }
+notify-debouncer-mini = { version = "0.3.0", optional = true }
+ignore = { version = "0.4.20", optional = true }
 
 # Serve feature
-futures-util = { version = "0.3.4", optional = true }
-tokio = { version = "1", features = ["macros", "rt-multi-thread"], optional = true }
-warp = { version = "0.3.2", default-features = false, features = ["websocket"], optional = true }
+futures-util = { version = "0.3.28", optional = true }
+tokio = { version = "1.28.1", features = ["macros", "rt-multi-thread"], optional = true }
+warp = { version = "0.3.5", default-features = false, features = ["websocket"], optional = true }
 
 # Search feature
-elasticlunr-rs = { version = "3.0.0", optional = true }
-ammonia = { version = "3", optional = true }
+elasticlunr-rs = { version = "3.0.2", optional = true }
+ammonia = { version = "3.3.0", optional = true }
 
 [dev-dependencies]
-assert_cmd = "1"
-predicates = "2"
-select = "0.5"
-semver = "1.0"
-pretty_assertions = "1.2.1"
-walkdir = "2.0"
+assert_cmd = "2.0.11"
+predicates = "3.0.3"
+select = "0.6.0"
+semver = "1.0.17"
+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"]
+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

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 +13,17 @@ 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
+fi
+
 rustup default $TOOLCHAIN
 rustup -V
 rustc -Vv

ci/make-release-asset.sh

@@ -11,16 +11,21 @@ fi
 TAG=${GITHUB_REF#*/tags/}
 
 host=$(rustc -Vv | grep ^host: | sed -e "s/host: //g")
+target=$2
+if [ "$host" != "$target" ]
+then
+  export "CARGO_TARGET_$(echo $target | tr a-z- A-Z_)_LINKER"=rust-lld
+fi
 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 +35,7 @@ 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 +44,10 @@ 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"),
         )
@@ -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);
+        }
+    }
 }

guide/book.toml

@@ -17,6 +17,9 @@ edit-url-template = "https://github.com/rust-lang/mdBook/edit/master/guide/{path
 editable = true
 line-numbers = true
 
+[output.html.code.hidelines]
+python = "~"
+
 [output.html.search]
 limit-results = 20
 use-boolean-and = true

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

@@ -67,4 +67,16 @@ mdbook init --title="my amazing book"
 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/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
 
@@ -43,7 +42,7 @@ mdbook test path/to/book
 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`:
@@ -61,3 +60,8 @@ 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/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/v0.4.19/mdbook-v0.4.19-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.35/mdbook-v0.4.35-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
 bin/mdbook build
 ```
 
@@ -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/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
@@ -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

@@ -126,7 +126,10 @@ The following configuration options are available:
   that occur in code blocks and code spans. Defaults to `false`.
 - **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 +150,9 @@ 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.
@@ -157,7 +160,8 @@ 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
@@ -178,7 +182,7 @@ 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 +218,25 @@ 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].

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~~.
@@ -220,3 +220,16 @@ To enable it, see the [`output.html.curly-quotes`] config option.
 [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
+
+### 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/specs/heading_attrs.txt).

guide/src/format/mdbook.md

@@ -2,11 +2,11 @@
 
 ## 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 use the `#` character as a prefix which will hide lines [like you would with Rustdoc][rustdoc-hide].
+
+[rustdoc-hide]: https://doc.rust-lang.org/stable/rustdoc/write-documentation/documentation-tests.html#hiding-portions-of-the-example
 
 ```bash
 # fn main() {
@@ -28,7 +28,47 @@ 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
 
@@ -274,3 +314,51 @@ 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
+fatique," 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
+fatique," where people are trained to ignore them because they usually don't
+matter for what they're doing.
+
+</div>

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/syntax-highlighting.md

@@ -77,38 +77,6 @@ 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 1.66.
 
 Once you have installed Rust, the following command can be used to build and install mdBook:
 

src/book/book.rs

@@ -8,7 +8,7 @@ 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.
@@ -39,9 +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);
@@ -277,7 +275,7 @@ 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())
@@ -317,7 +315,7 @@ 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);

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

@@ -14,6 +14,7 @@ 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 log::{debug, error, info, log_enabled, trace, warn};
 use std::io::Write;
 use std::path::PathBuf;
 use std::process::Command;
@@ -98,7 +99,7 @@ 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 +122,7 @@ 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 +196,26 @@ 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);
@@ -246,6 +252,13 @@ impl MDBook {
 
     /// Run `rustdoc` tests on the book, linking against the provided libraries.
     pub fn test(&mut self, library_paths: Vec<&str>) -> Result<()> {
+        // 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 library_args: Vec<&str> = (0..library_paths.len())
             .map(|_| "-L")
             .zip(library_paths.into_iter())
@@ -254,13 +267,27 @@ impl MDBook {
 
         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 mut failed = false;
         for item in book.iter() {
@@ -270,11 +297,19 @@ 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())?;
 
@@ -284,17 +319,18 @@ impl MDBook {
                 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"]);
                         }
                     }
                 }
 
+                debug!("running {:?}", cmd);
                 let output = cmd.output()?;
 
                 if !output.status.success() {
@@ -311,6 +347,11 @@ impl MDBook {
         if failed {
             bail!("One or more tests failed");
         }
+        if let Some(chapter) = chapter {
+            if !chapter_found {
+                bail!("Chapter not found: {}", chapter);
+            }
+        }
         Ok(())
     }
 

src/book/summary.rs

@@ -1,4 +1,5 @@
 use crate::errors::*;
+use log::{debug, trace, warn};
 use memchr::{self, Memchr};
 use pulldown_cmark::{self, Event, HeadingLevel, Tag};
 use serde::{Deserialize, Serialize};
@@ -453,7 +454,7 @@ 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;
                     }

src/cmd/build.rs

@@ -1,42 +1,30 @@
+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?
         let path = book.build_dir_for("html").join("index.html");
         if !path.exists() {

src/cmd/clean.rs

@@ -1,36 +1,24 @@
+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::path::PathBuf;
 
 // 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),
     };

src/cmd/command_prelude.rs

@@ -0,0 +1,45 @@
+//! 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"))
+    }
+}
+
+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()
     };
@@ -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()?;
 
@@ -122,5 +116,5 @@ fn confirm() -> bool {
     io::stdout().flush().unwrap();
     let mut s = String::new();
     io::stdin().read_line(&mut s).ok();
-    matches!(&*s.trim(), "Y" | "y" | "yes" | "Yes")
+    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

@@ -1,7 +1,8 @@
+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::*;
@@ -18,61 +19,48 @@ 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()
 }
 
 // Serve 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)?;
 
-    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 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);
 
@@ -115,7 +102,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         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| {
+        let result = MDBook::load(book_dir).and_then(|mut b| {
             update_config(&mut b);
             b.build()
         });

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::{Arg, ArgAction, ArgMatches, Command};
 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

@@ -1,49 +1,36 @@
+use super::command_prelude::*;
 use crate::{get_book_dir, open};
-use clap::{arg, App, Arg, ArgMatches};
+use ignore::gitignore::Gitignore;
 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;
 
 // 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()
 }
 
 // Watch 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)?;
 
     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()?;
         let path = book.build_dir_for("html").join("index.html");
         if !path.exists() {
@@ -55,7 +42,7 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 
     trigger_on_change(&book, |paths, book_dir| {
         info!("Files changed: {:?}\nBuilding book...\n", paths);
-        let result = MDBook::load(&book_dir).and_then(|mut b| {
+        let result = MDBook::load(book_dir).and_then(|mut b| {
             update_config(&mut b);
             b.build()
         });
@@ -76,14 +63,14 @@ fn remove_ignored_files(book_root: &Path, paths: &[PathBuf]) -> Vec<PathBuf> {
 
     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()
-                }
+            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.
@@ -99,18 +86,13 @@ fn find_gitignore(book_root: &Path) -> Option<PathBuf> {
         .find(|p| p.exists())
 }
 
-fn filter_ignored_files(exclusion_checker: gitignore::File, paths: &[PathBuf]) -> Vec<PathBuf> {
+fn filter_ignored_files(ignore: Gitignore, 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
-            }
+        .filter(|path| {
+            !ignore
+                .matched_path_or_any_parents(path, path.is_dir())
+                .is_ignore()
         })
         .map(|path| path.to_path_buf())
         .collect()
@@ -121,30 +103,47 @@ 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,
+    let mut debouncer = match notify_debouncer_mini::new_debouncer(Duration::from_secs(1), None, 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) {
+    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);
+    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);
+    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...");
 
@@ -155,18 +154,25 @@ where
 
         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,
+        let paths: Vec<_> = all_events
+            .filter_map(|event| match event {
+                Ok(events) => Some(events),
+                Err(errors) => {
+                    for error in errors {
+                        log::warn!("error while watching for changes: {error}");
+                    }
+                    None
                 }
             })
-            .collect::<Vec<_>>();
+            .flatten()
+            .map(|event| event.path)
+            .collect();
 
-        let paths = remove_ignored_files(&book.root, &paths[..]);
+        // 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() {
             closure(paths, &book.root);

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;
@@ -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)?;
 
@@ -307,7 +308,7 @@ 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));
         }
 
@@ -410,6 +411,9 @@ pub struct BookConfig {
     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 {
@@ -421,6 +425,43 @@ 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,
         }
     }
 }
@@ -437,6 +478,8 @@ 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 {
@@ -445,6 +488,7 @@ impl Default for BuildConfig {
             build_dir: PathBuf::from("book"),
             create_missing: true,
             use_default_preprocessors: true,
+            extra_watch_dirs: Vec::new(),
         }
     }
 }
@@ -500,6 +544,8 @@ 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.
@@ -526,10 +572,9 @@ 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)]
@@ -553,6 +598,7 @@ 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,
@@ -639,6 +685,22 @@ impl Default for Playground {
     }
 }
 
+/// Configuration for tweaking how the the HTML renderer handles code blocks.
+#[derive(Debug, 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>,
+}
+
+impl Default for Code {
+    fn default() -> Code {
+        Code {
+            hidelines: HashMap::new(),
+        }
+    }
+}
+
 /// Configuration of the search functionality of the HTML renderer.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "kebab-case")]
@@ -700,7 +762,7 @@ 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;
         }
@@ -717,6 +779,7 @@ 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]
@@ -765,11 +828,13 @@ 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 {
@@ -980,6 +1045,7 @@ 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 {
@@ -1115,6 +1181,73 @@ 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() {

src/lib.rs

@@ -83,17 +83,6 @@
 #![deny(missing_docs)]
 #![deny(rust_2018_idioms)]
 
-#[macro_use]
-extern crate lazy_static;
-#[macro_use]
-extern crate log;
-#[macro_use]
-extern crate serde_json;
-
-#[cfg(test)]
-#[macro_use]
-extern crate pretty_assertions;
-
 pub mod book;
 pub mod config;
 pub mod preprocess;

src/main.rs

@@ -5,7 +5,7 @@ extern crate log;
 
 use anyhow::anyhow;
 use chrono::Local;
-use clap::{App, AppSettings, Arg, ArgMatches};
+use clap::{Arg, ArgMatches, Command};
 use clap_complete::Shell;
 use env_logger::Builder;
 use log::LevelFilter;
@@ -13,7 +13,7 @@ use mdbook::utils;
 use std::env;
 use std::ffi::OsStr;
 use std::io::Write;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 mod cmd;
 
@@ -22,10 +22,10 @@ const VERSION: &str = concat!("v", crate_version!());
 fn main() {
     init_logger();
 
-    let app = create_clap_app();
+    let command = create_clap_command();
 
-    // Check which subcomamnd the user ran...
-    let res = match app.get_matches().subcommand() {
+    // Check which subcommand the user ran...
+    let res = match command.get_matches().subcommand() {
         Some(("init", sub_matches)) => cmd::init::execute(sub_matches),
         Some(("build", sub_matches)) => cmd::build::execute(sub_matches),
         Some(("clean", sub_matches)) => cmd::clean::execute(sub_matches),
@@ -35,15 +35,13 @@ fn main() {
         Some(("serve", sub_matches)) => cmd::serve::execute(sub_matches),
         Some(("test", sub_matches)) => cmd::test::execute(sub_matches),
         Some(("completions", sub_matches)) => (|| {
-            let shell: Shell = sub_matches
-                .value_of("shell")
-                .ok_or_else(|| anyhow!("Shell name missing."))?
-                .parse()
-                .map_err(|s| anyhow!("Invalid shell: {}", s))?;
+            let shell = sub_matches
+                .get_one::<Shell>("shell")
+                .ok_or_else(|| anyhow!("Shell name missing."))?;
 
-            let mut complete_app = create_clap_app();
+            let mut complete_app = create_clap_command();
             clap_complete::generate(
-                shell,
+                *shell,
                 &mut complete_app,
                 "mdbook",
                 &mut std::io::stdout().lock(),
@@ -61,13 +59,13 @@ fn main() {
 }
 
 /// Create a list of valid arguments and sub-commands
-fn create_clap_app() -> App<'static> {
-    let app = App::new(crate_name!())
+fn create_clap_command() -> Command {
+    let app = Command::new(crate_name!())
         .about(crate_description!())
         .author("Mathieu David <mathieudavid@mathieudavid.org>")
         .version(VERSION)
-        .setting(AppSettings::PropagateVersion)
-        .setting(AppSettings::ArgRequiredElseHelp)
+        .propagate_version(true)
+        .arg_required_else_help(true)
         .after_help(
             "For more information about a specific command, try `mdbook <command> --help`\n\
              The source code for mdBook is available at: https://github.com/rust-lang/mdBook",
@@ -77,12 +75,11 @@ fn create_clap_app() -> App<'static> {
         .subcommand(cmd::test::make_subcommand())
         .subcommand(cmd::clean::make_subcommand())
         .subcommand(
-            App::new("completions")
+            Command::new("completions")
                 .about("Generate shell completions for your shell to stdout")
                 .arg(
                     Arg::new("shell")
-                        .takes_value(true)
-                        .possible_values(Shell::possible_values())
+                        .value_parser(clap::value_parser!(Shell))
                         .help("the shell to generate completions for")
                         .value_name("SHELL")
                         .required(true),
@@ -124,11 +121,10 @@ fn init_logger() {
 }
 
 fn get_book_dir(args: &ArgMatches) -> PathBuf {
-    if let Some(dir) = args.value_of("dir") {
+    if let Some(p) = args.get_one::<PathBuf>("dir") {
         // Check if path is relative from current dir, or absolute...
-        let p = Path::new(dir);
         if p.is_relative() {
-            env::current_dir().unwrap().join(dir)
+            env::current_dir().unwrap().join(p)
         } else {
             p.to_path_buf()
         }
@@ -146,5 +142,5 @@ fn open<P: AsRef<OsStr>>(path: P) {
 
 #[test]
 fn verify_app() {
-    create_clap_app().debug_assert();
+    create_clap_command().debug_assert();
 }

src/preprocess/cmd.rs

@@ -1,6 +1,7 @@
 use super::{Preprocessor, PreprocessorContext};
 use crate::book::Book;
 use crate::errors::*;
+use log::{debug, trace, warn};
 use shlex::Shlex;
 use std::io::{self, Read, Write};
 use std::process::{Child, Command, Stdio};

src/preprocess/index.rs

@@ -1,10 +1,11 @@
 use regex::Regex;
 use std::path::Path;
 
-use crate::errors::*;
-
 use super::{Preprocessor, PreprocessorContext};
 use crate::book::{Book, BookItem};
+use crate::errors::*;
+use log::warn;
+use once_cell::sync::Lazy;
 
 /// A preprocessor for converting file name `README.md` to `index.md` since
 /// `README.md` is the de facto index file in markdown-based documentation.
@@ -67,9 +68,8 @@ fn warn_readme_name_conflict<P: AsRef<Path>>(readme_path: P, index_path: P) {
 }
 
 fn is_readme_file<P: AsRef<Path>>(path: P) -> bool {
-    lazy_static! {
-        static ref RE: Regex = Regex::new(r"(?i)^readme$").unwrap();
-    }
+    static RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"(?i)^readme$").unwrap());
+
     RE.is_match(
         path.as_ref()
             .file_stem()

src/preprocess/links.rs

@@ -10,6 +10,8 @@ use std::path::{Path, PathBuf};
 
 use super::{Preprocessor, PreprocessorContext};
 use crate::book::{Book, BookItem};
+use log::{error, warn};
+use once_cell::sync::Lazy;
 
 const ESCAPE_CHAR: char = '\\';
 const MAX_LINK_NESTED_DEPTH: usize = 10;
@@ -91,7 +93,7 @@ where
     for link in find_links(s) {
         replaced.push_str(&s[previous_end_index..link.start_index]);
 
-        match link.render_with_path(&path, chapter_title) {
+        match link.render_with_path(path, chapter_title) {
             Ok(new_content) => {
                 if depth < MAX_LINK_NESTED_DEPTH {
                     if let Some(rel_path) = link.link_type.relative_path(path) {
@@ -325,7 +327,7 @@ impl<'a> Link<'a> {
         let base = base.as_ref();
         match self.link_type {
             // omit the escape char
-            LinkType::Escaped => Ok((&self.link_text[1..]).to_owned()),
+            LinkType::Escaped => Ok(self.link_text[1..].to_owned()),
             LinkType::Include(ref pat, ref range_or_anchor) => {
                 let target = base.join(pat);
 
@@ -408,19 +410,20 @@ impl<'a> Iterator for LinkIter<'a> {
 fn find_links(contents: &str) -> LinkIter<'_> {
     // lazily compute following regex
     // r"\\\{\{#.*\}\}|\{\{#([a-zA-Z0-9]+)\s*([^}]+)\}\}")?;
-    lazy_static! {
-        static ref RE: Regex = Regex::new(
+    static RE: Lazy<Regex> = Lazy::new(|| {
+        Regex::new(
             r"(?x)              # insignificant whitespace mode
-            \\\{\{\#.*\}\}      # match escaped link
-            |                   # or
-            \{\{\s*             # link opening parens and whitespace
-            \#([a-zA-Z0-9_]+)   # link type
-            \s+                 # separating whitespace
-            ([^}]+)             # link target path and space separated properties
-            \}\}                # link closing parens"
+        \\\{\{\#.*\}\}      # match escaped link
+        |                   # or
+        \{\{\s*             # link opening parens and whitespace
+        \#([a-zA-Z0-9_]+)   # link type
+        \s+                 # separating whitespace
+        ([^}]+)             # link target path and space separated properties
+        \}\}                # link closing parens",
         )
-        .unwrap();
-    }
+        .unwrap()
+    });
+
     LinkIter(RE.captures_iter(contents))
 }
 

src/preprocess/mod.rs

@@ -12,12 +12,11 @@ use crate::book::Book;
 use crate::config::Config;
 use crate::errors::*;
 
+use serde::{Deserialize, Serialize};
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::path::PathBuf;
 
-use serde::{Deserialize, Serialize};
-
 /// Extra information for a `Preprocessor` to give them more context when
 /// processing a book.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]

src/renderer/html_handlebars/hbs_renderer.rs

@@ -1,5 +1,5 @@
 use crate::book::{Book, BookItem};
-use crate::config::{BookConfig, Config, HtmlConfig, Playground, RustEdition};
+use crate::config::{BookConfig, Code, Config, HtmlConfig, Playground, RustEdition};
 use crate::errors::*;
 use crate::renderer::html_handlebars::helpers;
 use crate::renderer::{RenderContext, Renderer};
@@ -14,7 +14,10 @@ use std::path::{Path, PathBuf};
 
 use crate::utils::fs::get_404_output_file;
 use handlebars::Handlebars;
+use log::{debug, trace, warn};
+use once_cell::sync::Lazy;
 use regex::{Captures, Regex};
+use serde_json::json;
 
 #[derive(Default)]
 pub struct HtmlHandlebars;
@@ -96,7 +99,7 @@ impl HtmlHandlebars {
         ctx.data.insert("title".to_owned(), json!(title));
         ctx.data.insert(
             "path_to_root".to_owned(),
-            json!(utils::fs::path_to_root(&path)),
+            json!(utils::fs::path_to_root(path)),
         );
         if let Some(ref section) = ch.number {
             ctx.data
@@ -107,7 +110,12 @@ impl HtmlHandlebars {
         debug!("Render template");
         let rendered = ctx.handlebars.render("index", &ctx.data)?;
 
-        let rendered = self.post_process(rendered, &ctx.html_config.playground, ctx.edition);
+        let rendered = self.post_process(
+            rendered,
+            &ctx.html_config.playground,
+            &ctx.html_config.code,
+            ctx.edition,
+        );
 
         // Write to file
         debug!("Creating {}", filepath.display());
@@ -118,8 +126,12 @@ impl HtmlHandlebars {
             ctx.data.insert("path_to_root".to_owned(), json!(""));
             ctx.data.insert("is_index".to_owned(), json!(true));
             let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
-            let rendered_index =
-                self.post_process(rendered_index, &ctx.html_config.playground, ctx.edition);
+            let rendered_index = self.post_process(
+                rendered_index,
+                &ctx.html_config.playground,
+                &ctx.html_config.code,
+                ctx.edition,
+            );
             debug!("Creating index.html from {}", ctx_path);
             utils::fs::write_file(&ctx.destination, "index.html", rendered_index.as_bytes())?;
         }
@@ -179,8 +191,12 @@ impl HtmlHandlebars {
         data_404.insert("title".to_owned(), json!(title));
         let rendered = handlebars.render("index", &data_404)?;
 
-        let rendered =
-            self.post_process(rendered, &html_config.playground, ctx.config.rust.edition);
+        let rendered = self.post_process(
+            rendered,
+            &html_config.playground,
+            &html_config.code,
+            ctx.config.rust.edition,
+        );
         let output_file = get_404_output_file(&html_config.input_404);
         utils::fs::write_file(destination, output_file, rendered.as_bytes())?;
         debug!("Creating 404.html ✓");
@@ -192,11 +208,13 @@ impl HtmlHandlebars {
         &self,
         rendered: String,
         playground_config: &Playground,
+        code_config: &Code,
         edition: Option<RustEdition>,
     ) -> String {
         let rendered = build_header_links(&rendered);
         let rendered = fix_code_blocks(&rendered);
         let rendered = add_playground_pre(&rendered, playground_config, edition);
+        let rendered = hide_lines(&rendered, code_config);
 
         rendered
     }
@@ -272,7 +290,8 @@ impl HtmlHandlebars {
             "FontAwesome/fonts/FontAwesome.ttf",
             theme::FONT_AWESOME_TTF,
         )?;
-        if html_config.copy_fonts {
+        // Don't copy the stock fonts if the user has specified their own fonts to use.
+        if html_config.copy_fonts && theme.fonts_css.is_none() {
             write_file(destination, "fonts/fonts.css", theme::fonts::CSS)?;
             for (file_name, contents) in theme::fonts::LICENSES.iter() {
                 write_file(destination, file_name, contents)?;
@@ -286,6 +305,24 @@ impl HtmlHandlebars {
                 theme::fonts::SOURCE_CODE_PRO.1,
             )?;
         }
+        if let Some(fonts_css) = &theme.fonts_css {
+            if !fonts_css.is_empty() {
+                write_file(destination, "fonts/fonts.css", fonts_css)?;
+            }
+        }
+        if !html_config.copy_fonts && theme.fonts_css.is_none() {
+            warn!(
+                "output.html.copy-fonts is deprecated.\n\
+                This book appears to have copy-fonts=false in book.toml without a fonts.css file.\n\
+                Add an empty `theme/fonts/fonts.css` file to squelch this warning."
+            );
+        }
+        for font_file in &theme.font_files {
+            let contents = fs::read(font_file)?;
+            let filename = font_file.file_name().unwrap();
+            let filename = Path::new("fonts").join(filename);
+            write_file(destination, filename, &contents)?;
+        }
 
         let playground_config = &html_config.playground;
 
@@ -337,6 +374,7 @@ impl HtmlHandlebars {
         );
         handlebars.register_helper("previous", Box::new(helpers::navigation::previous));
         handlebars.register_helper("next", Box::new(helpers::navigation::next));
+        // TODO: remove theme_option in 0.5, it is not needed.
         handlebars.register_helper("theme_option", Box::new(helpers::theme::theme_option));
     }
 
@@ -524,7 +562,7 @@ impl Renderer for HtmlHandlebars {
         // Print version
         let mut print_content = String::new();
 
-        fs::create_dir_all(&destination)
+        fs::create_dir_all(destination)
             .with_context(|| "Unexpected error when constructing destination path")?;
 
         let mut is_index = true;
@@ -560,8 +598,12 @@ impl Renderer for HtmlHandlebars {
             debug!("Render template");
             let rendered = handlebars.render("index", &data)?;
 
-            let rendered =
-                self.post_process(rendered, &html_config.playground, ctx.config.rust.edition);
+            let rendered = self.post_process(
+                rendered,
+                &html_config.playground,
+                &html_config.code,
+                ctx.config.rust.edition,
+            );
 
             utils::fs::write_file(destination, "print.html", rendered.as_bytes())?;
             debug!("Creating print.html ✓");
@@ -606,6 +648,10 @@ fn make_data(
         "language".to_owned(),
         json!(config.book.language.clone().unwrap_or_default()),
     );
+    data.insert(
+        "text_direction".to_owned(),
+        json!(config.book.realized_text_direction()),
+    );
     data.insert(
         "book_title".to_owned(),
         json!(config.book.title.clone().unwrap_or_default()),
@@ -627,6 +673,7 @@ fn make_data(
         );
     }
 
+    // TODO: remove default_theme in 0.5, it is not needed.
     let default_theme = match html_config.default_theme {
         Some(ref theme) => theme.to_lowercase(),
         None => "light".to_string(),
@@ -651,7 +698,8 @@ fn make_data(
         data.insert("mathjax_support".to_owned(), json!(true));
     }
 
-    if html_config.copy_fonts {
+    // This `matches!` checks for a non-empty file.
+    if html_config.copy_fonts || matches!(theme.fonts_css.as_deref(), Some([_, ..])) {
         data.insert("copy_fonts".to_owned(), json!(true));
     }
 
@@ -764,9 +812,10 @@ fn make_data(
 /// Goes through the rendered HTML, making sure all header tags have
 /// an anchor respectively so people can link to sections directly.
 fn build_header_links(html: &str) -> String {
-    lazy_static! {
-        static ref BUILD_HEADER_LINKS: Regex = Regex::new(r"<h(\d)>(.*?)</h\d>").unwrap();
-    }
+    static BUILD_HEADER_LINKS: Lazy<Regex> = Lazy::new(|| {
+        Regex::new(r#"<h(\d)(?: id="([^"]+)")?(?: class="([^"]+)")?>(.*?)</h\d>"#).unwrap()
+    });
+    static IGNORE_CLASS: &[&str] = &["menu-title"];
 
     let mut id_counter = HashMap::new();
 
@@ -776,7 +825,22 @@ fn build_header_links(html: &str) -> String {
                 .parse()
                 .expect("Regex should ensure we only ever get numbers here");
 
-            insert_link_into_header(level, &caps[2], &mut id_counter)
+            // Ignore .menu-title because now it's getting detected by the regex.
+            if let Some(classes) = caps.get(3) {
+                for class in classes.as_str().split(" ") {
+                    if IGNORE_CLASS.contains(&class) {
+                        return caps[0].to_string();
+                    }
+                }
+            }
+
+            insert_link_into_header(
+                level,
+                &caps[4],
+                caps.get(2).map(|x| x.as_str().to_string()),
+                caps.get(3).map(|x| x.as_str().to_string()),
+                &mut id_counter,
+            )
         })
         .into_owned()
 }
@@ -786,15 +850,21 @@ fn build_header_links(html: &str) -> String {
 fn insert_link_into_header(
     level: usize,
     content: &str,
+    id: Option<String>,
+    classes: Option<String>,
     id_counter: &mut HashMap<String, usize>,
 ) -> String {
-    let id = utils::unique_id_from_content(content, id_counter);
+    let id = id.unwrap_or_else(|| utils::unique_id_from_content(content, id_counter));
+    let classes = classes
+        .map(|s| format!(" class=\"{s}\""))
+        .unwrap_or_default();
 
     format!(
-        r##"<h{level} id="{id}"><a class="header" href="#{id}">{text}</a></h{level}>"##,
+        r##"<h{level} id="{id}"{classes}><a class="header" href="#{id}">{text}</a></h{level}>"##,
         level = level,
         id = id,
-        text = content
+        text = content,
+        classes = classes
     )
 }
 
@@ -807,10 +877,8 @@ fn insert_link_into_header(
 // ```
 // This function replaces all commas by spaces in the code block classes
 fn fix_code_blocks(html: &str) -> String {
-    lazy_static! {
-        static ref FIX_CODE_BLOCKS: Regex =
-            Regex::new(r##"<code([^>]+)class="([^"]+)"([^>]*)>"##).unwrap();
-    }
+    static FIX_CODE_BLOCKS: Lazy<Regex> =
+        Lazy::new(|| Regex::new(r##"<code([^>]+)class="([^"]+)"([^>]*)>"##).unwrap());
 
     FIX_CODE_BLOCKS
         .replace_all(html, |caps: &Captures<'_>| {
@@ -828,68 +896,64 @@ fn fix_code_blocks(html: &str) -> String {
         .into_owned()
 }
 
+static CODE_BLOCK_RE: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r##"((?s)<code[^>]?class="([^"]+)".*?>(.*?)</code>)"##).unwrap());
+
 fn add_playground_pre(
     html: &str,
     playground_config: &Playground,
     edition: Option<RustEdition>,
 ) -> String {
-    lazy_static! {
-        static ref ADD_PLAYGROUND_PRE: Regex =
-            Regex::new(r##"((?s)<code[^>]?class="([^"]+)".*?>(.*?)</code>)"##).unwrap();
-    }
-    ADD_PLAYGROUND_PRE
+    CODE_BLOCK_RE
         .replace_all(html, |caps: &Captures<'_>| {
             let text = &caps[1];
             let classes = &caps[2];
             let code = &caps[3];
 
-            if classes.contains("language-rust") {
-                if (!classes.contains("ignore")
+            if classes.contains("language-rust")
+                && ((!classes.contains("ignore")
                     && !classes.contains("noplayground")
                     && !classes.contains("noplaypen")
                     && playground_config.runnable)
-                    || classes.contains("mdbook-runnable")
-                {
-                    let contains_e2015 = classes.contains("edition2015");
-                    let contains_e2018 = classes.contains("edition2018");
-                    let contains_e2021 = classes.contains("edition2021");
-                    let edition_class = if contains_e2015 || contains_e2018 || contains_e2021 {
-                        // the user forced edition, we should not overwrite it
-                        ""
-                    } else {
-                        match edition {
-                            Some(RustEdition::E2015) => " edition2015",
-                            Some(RustEdition::E2018) => " edition2018",
-                            Some(RustEdition::E2021) => " edition2021",
-                            None => "",
-                        }
-                    };
-
-                    // wrap the contents in an external pre block
-                    format!(
-                        "<pre class=\"playground\"><code class=\"{}{}\">{}</code></pre>",
-                        classes,
-                        edition_class,
-                        {
-                            let content: Cow<'_, str> = if playground_config.editable
-                                && classes.contains("editable")
-                                || text.contains("fn main")
-                                || text.contains("quick_main!")
-                            {
-                                code.into()
-                            } else {
-                                // we need to inject our own main
-                                let (attrs, code) = partition_source(code);
-
-                                format!("# #![allow(unused)]\n{}#fn main() {{\n{}#}}", attrs, code)
-                                    .into()
-                            };
-                            hide_lines(&content)
-                        }
-                    )
+                    || classes.contains("mdbook-runnable"))
+            {
+                let contains_e2015 = classes.contains("edition2015");
+                let contains_e2018 = classes.contains("edition2018");
+                let contains_e2021 = classes.contains("edition2021");
+                let edition_class = if contains_e2015 || contains_e2018 || contains_e2021 {
+                    // the user forced edition, we should not overwrite it
+                    ""
                 } else {
-                    format!("<code class=\"{}\">{}</code>", classes, hide_lines(code))
-                }
+                    match edition {
+                        Some(RustEdition::E2015) => " edition2015",
+                        Some(RustEdition::E2018) => " edition2018",
+                        Some(RustEdition::E2021) => " edition2021",
+                        None => "",
+                    }
+                };
+
+                // wrap the contents in an external pre block
+                format!(
+                    "<pre class=\"playground\"><code class=\"{}{}\">{}</code></pre>",
+                    classes,
+                    edition_class,
+                    {
+                        let content: Cow<'_, str> = if playground_config.editable
+                            && classes.contains("editable")
+                            || text.contains("fn main")
+                            || text.contains("quick_main!")
+                        {
+                            code.into()
+                        } else {
+                            // we need to inject our own main
+                            let (attrs, code) = partition_source(code);
+
+                            format!("# #![allow(unused)]\n{}#fn main() {{\n{}#}}", attrs, code)
+                                .into()
+                        };
+                        content
+                    }
+                )
             } else {
                 // not language-rust, so no-op
                 text.to_owned()
@@ -898,19 +962,63 @@ fn add_playground_pre(
         .into_owned()
 }
 
-fn hide_lines(content: &str) -> String {
-    lazy_static! {
-        static ref BORING_LINES_REGEX: Regex = Regex::new(r"^(\s*)#(.?)(.*)$").unwrap();
-    }
+/// Modifies all `<code>` blocks to convert "hidden" lines and to wrap them in
+/// a `<span class="boring">`.
+fn hide_lines(html: &str, code_config: &Code) -> String {
+    let language_regex = Regex::new(r"\blanguage-(\w+)\b").unwrap();
+    let hidelines_regex = Regex::new(r"\bhidelines=(\S+)").unwrap();
+    CODE_BLOCK_RE
+        .replace_all(html, |caps: &Captures<'_>| {
+            let text = &caps[1];
+            let classes = &caps[2];
+            let code = &caps[3];
+
+            if classes.contains("language-rust") {
+                format!(
+                    "<code class=\"{}\">{}</code>",
+                    classes,
+                    hide_lines_rust(code)
+                )
+            } else {
+                // First try to get the prefix from the code block
+                let hidelines_capture = hidelines_regex.captures(classes);
+                let hidelines_prefix = match &hidelines_capture {
+                    Some(capture) => Some(&capture[1]),
+                    None => {
+                        // Then look up the prefix by language
+                        language_regex.captures(classes).and_then(|capture| {
+                            code_config.hidelines.get(&capture[1]).map(|p| p.as_str())
+                        })
+                    }
+                };
+
+                match hidelines_prefix {
+                    Some(prefix) => format!(
+                        "<code class=\"{}\">{}</code>",
+                        classes,
+                        hide_lines_with_prefix(code, prefix)
+                    ),
+                    None => text.to_owned(),
+                }
+            }
+        })
+        .into_owned()
+}
+
+fn hide_lines_rust(content: &str) -> String {
+    static BORING_LINES_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"^(\s*)#(.?)(.*)$").unwrap());
 
     let mut result = String::with_capacity(content.len());
-    for line in content.lines() {
+    let mut lines = content.lines().peekable();
+    while let Some(line) = lines.next() {
+        // Don't include newline on the last line.
+        let newline = if lines.peek().is_none() { "" } else { "\n" };
         if let Some(caps) = BORING_LINES_REGEX.captures(line) {
             if &caps[2] == "#" {
                 result += &caps[1];
                 result += &caps[2];
                 result += &caps[3];
-                result += "\n";
+                result += newline;
                 continue;
             } else if &caps[2] != "!" && &caps[2] != "[" {
                 result += "<span class=\"boring\">";
@@ -919,12 +1027,32 @@ fn hide_lines(content: &str) -> String {
                     result += &caps[2];
                 }
                 result += &caps[3];
-                result += "\n";
+                result += newline;
                 result += "</span>";
                 continue;
             }
         }
         result += line;
+        result += newline;
+    }
+    result
+}
+
+fn hide_lines_with_prefix(content: &str, prefix: &str) -> String {
+    let mut result = String::with_capacity(content.len());
+    for line in content.lines() {
+        if line.trim_start().starts_with(prefix) {
+            let pos = line.find(prefix).unwrap();
+            let (ws, rest) = (&line[..pos], &line[pos + prefix.len()..]);
+
+            result += "<span class=\"boring\">";
+            result += ws;
+            result += rest;
+            result += "\n";
+            result += "</span>";
+            continue;
+        }
+        result += line;
         result += "\n";
     }
     result
@@ -964,7 +1092,10 @@ struct RenderItemContext<'a> {
 
 #[cfg(test)]
 mod tests {
+    use crate::config::TextDirection;
+
     use super::*;
+    use pretty_assertions::assert_eq;
 
     #[test]
     fn original_build_header_links() {
@@ -993,6 +1124,21 @@ mod tests {
                 "<h1>Foo</h1><h3>Foo</h3>",
                 r##"<h1 id="foo"><a class="header" href="#foo">Foo</a></h1><h3 id="foo-1"><a class="header" href="#foo-1">Foo</a></h3>"##,
             ),
+            // id only
+            (
+                r##"<h1 id="foobar">Foo</h1>"##,
+                r##"<h1 id="foobar"><a class="header" href="#foobar">Foo</a></h1>"##,
+            ),
+            // class only
+            (
+                r##"<h1 class="class1 class2">Foo</h1>"##,
+                r##"<h1 id="foo" class="class1 class2"><a class="header" href="#foo">Foo</a></h1>"##,
+            ),
+            // both id and class
+            (
+                r##"<h1 id="foobar" class="class1 class2">Foo</h1>"##,
+                r##"<h1 id="foobar" class="class1 class2"><a class="header" href="#foobar">Foo</a></h1>"##,
+            ),
         ];
 
         for (src, should_be) in inputs {
@@ -1005,19 +1151,19 @@ mod tests {
     fn add_playground() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}\n</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>"),
           ("<code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span><span class=\"boring\">\n</span>\";\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>"),
           ("<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
-           "<code class=\"language-rust ignore\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";\n</code>"),
+           "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>"),
           ("<code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code>",
-           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>"),
         ];
         for (src, should_be) in &inputs {
             let got = add_playground_pre(
@@ -1035,13 +1181,13 @@ mod tests {
     fn add_playground_edition2015() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2015\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}\n</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2015\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2015\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2018\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}</code></pre>"),
         ];
         for (src, should_be) in &inputs {
             let got = add_playground_pre(
@@ -1059,13 +1205,13 @@ mod tests {
     fn add_playground_edition2018() {
         let inputs = [
           ("<code class=\"language-rust\">x()</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2018\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}\n</span></code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2018\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
           ("<code class=\"language-rust\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2015\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}</code></pre>"),
           ("<code class=\"language-rust edition2018\">fn main() {}</code>",
-           "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}\n</code></pre>"),
+           "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}</code></pre>"),
         ];
         for (src, should_be) in &inputs {
             let got = add_playground_pre(
@@ -1083,13 +1229,13 @@ mod tests {
     fn add_playground_edition2021() {
         let inputs = [
             ("<code class=\"language-rust\">x()</code>",
-             "<pre class=\"playground\"><code class=\"language-rust edition2021\"><span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}\n</span></code></pre>"),
+             "<pre class=\"playground\"><code class=\"language-rust edition2021\"># #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>"),
             ("<code class=\"language-rust\">fn main() {}</code>",
-             "<pre class=\"playground\"><code class=\"language-rust edition2021\">fn main() {}\n</code></pre>"),
+             "<pre class=\"playground\"><code class=\"language-rust edition2021\">fn main() {}</code></pre>"),
             ("<code class=\"language-rust edition2015\">fn main() {}</code>",
-             "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}\n</code></pre>"),
+             "<pre class=\"playground\"><code class=\"language-rust edition2015\">fn main() {}</code></pre>"),
             ("<code class=\"language-rust edition2018\">fn main() {}</code>",
-             "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}\n</code></pre>"),
+             "<pre class=\"playground\"><code class=\"language-rust edition2018\">fn main() {}</code></pre>"),
         ];
         for (src, should_be) in &inputs {
             let got = add_playground_pre(
@@ -1103,4 +1249,66 @@ mod tests {
             assert_eq!(&*got, *should_be);
         }
     }
+
+    #[test]
+    fn hide_lines_language_rust() {
+        let inputs = [
+          (
+           "<pre class=\"playground\"><code class=\"language-rust\">\n# #![allow(unused)]\n#fn main() {\nx()\n#}</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust\">\n<span class=\"boring\">#![allow(unused)]\n</span><span class=\"boring\">fn main() {\n</span>x()\n<span class=\"boring\">}</span></code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust\">fn main() {}</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n ## bar\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n\";</code></pre>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n # bar\n#\n\";</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">let s = \"foo\n<span class=\"boring\"> bar\n</span><span class=\"boring\">\n</span>\";</code></pre>",),
+          (
+           "<code class=\"language-rust ignore\">let s = \"foo\n # bar\n\";</code>",
+           "<code class=\"language-rust ignore\">let s = \"foo\n<span class=\"boring\"> bar\n</span>\";</code>",),
+          (
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>",
+           "<pre class=\"playground\"><code class=\"language-rust editable\">#![no_std]\nlet s = \"foo\";\n #[some_attr]</code></pre>",),
+        ];
+        for (src, should_be) in &inputs {
+            let got = hide_lines(src, &Code::default());
+            assert_eq!(&*got, *should_be);
+        }
+    }
+
+    #[test]
+    fn hide_lines_language_other() {
+        let inputs = [
+          (
+           "<code class=\"language-python\">~hidden()\nnothidden():\n~    hidden()\n    ~hidden()\n    nothidden()</code>",
+           "<code class=\"language-python\"><span class=\"boring\">hidden()\n</span>nothidden():\n<span class=\"boring\">    hidden()\n</span><span class=\"boring\">    hidden()\n</span>    nothidden()\n</code>",),
+           (
+            "<code class=\"language-python hidelines=!!!\">!!!hidden()\nnothidden():\n!!!    hidden()\n    !!!hidden()\n    nothidden()</code>",
+            "<code class=\"language-python hidelines=!!!\"><span class=\"boring\">hidden()\n</span>nothidden():\n<span class=\"boring\">    hidden()\n</span><span class=\"boring\">    hidden()\n</span>    nothidden()\n</code>",),
+        ];
+        for (src, should_be) in &inputs {
+            let got = hide_lines(
+                src,
+                &Code {
+                    hidelines: {
+                        let mut map = HashMap::new();
+                        map.insert("python".to_string(), "~".to_string());
+                        map
+                    },
+                },
+            );
+            assert_eq!(&*got, *should_be);
+        }
+    }
+
+    #[test]
+    fn test_json_direction() {
+        assert_eq!(json!(TextDirection::RightToLeft), json!("rtl"));
+        assert_eq!(json!(TextDirection::LeftToRight), json!("ltr"));
+    }
 }

src/renderer/html_handlebars/helpers/navigation.rs

@@ -4,6 +4,8 @@ use std::path::Path;
 use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError, Renderable};
 
 use crate::utils;
+use log::{debug, trace};
+use serde_json::json;
 
 type StringMap = BTreeMap<String, String>;
 
@@ -125,7 +127,7 @@ fn render(
 
     context.insert(
         "path_to_root".to_owned(),
-        json!(utils::fs::path_to_root(&base_path)),
+        json!(utils::fs::path_to_root(base_path)),
     );
 
     chapter
@@ -146,15 +148,12 @@ fn render(
 
     trace!("Render template");
 
-    _h.template()
-        .ok_or_else(|| RenderError::new("Error with the handlebars template"))
-        .and_then(|t| {
-            let mut local_rc = rc.clone();
-            let local_ctx = Context::wraps(&context)?;
-            t.render(r, &local_ctx, &mut local_rc, out)
-        })?;
-
-    Ok(())
+    let t = _h
+        .template()
+        .ok_or_else(|| RenderError::new("Error with the handlebars template"))?;
+    let local_ctx = Context::wraps(&context)?;
+    let mut local_rc = rc.clone();
+    t.render(r, &local_ctx, &mut local_rc, out)
 }
 
 pub fn previous(

src/renderer/html_handlebars/helpers/theme.rs

@@ -1,4 +1,5 @@
 use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError};
+use log::trace;
 
 pub fn theme_option(
     h: &Helper<'_, '_>,

src/renderer/html_handlebars/helpers/toc.rs

@@ -117,35 +117,35 @@ impl HelperDef for RenderToc {
             }
 
             // Link
-            let path_exists = if let Some(path) =
-                item.get("path")
-                    .and_then(|p| if p.is_empty() { None } else { Some(p) })
-            {
-                out.write("<a href=\"")?;
+            let path_exists: bool;
+            match item.get("path") {
+                Some(path) if !path.is_empty() => {
+                    out.write("<a href=\"")?;
+                    let tmp = Path::new(path)
+                        .with_extension("html")
+                        .to_str()
+                        .unwrap()
+                        // Hack for windows who tends to use `\` as separator instead of `/`
+                        .replace('\\', "/");
 
-                let tmp = Path::new(item.get("path").expect("Error: path should be Some(_)"))
-                    .with_extension("html")
-                    .to_str()
-                    .unwrap()
-                    // Hack for windows who tends to use `\` as separator instead of `/`
-                    .replace('\\', "/");
+                    // Add link
+                    out.write(&utils::fs::path_to_root(&current_path))?;
+                    out.write(&tmp)?;
+                    out.write("\"")?;
 
-                // Add link
-                out.write(&utils::fs::path_to_root(&current_path))?;
-                out.write(&tmp)?;
-                out.write("\"")?;
+                    if path == &current_path || is_first_chapter {
+                        is_first_chapter = false;
+                        out.write(" class=\"active\"")?;
+                    }
 
-                if path == &current_path || is_first_chapter {
-                    is_first_chapter = false;
-                    out.write(" class=\"active\"")?;
+                    out.write(">")?;
+                    path_exists = true;
                 }
-
-                out.write(">")?;
-                true
-            } else {
-                out.write("<div>")?;
-                false
-            };
+                _ => {
+                    out.write("<div>")?;
+                    path_exists = false;
+                }
+            }
 
             if !self.no_section_label {
                 // Section does not necessarily exist

src/renderer/html_handlebars/search.rs

@@ -3,6 +3,7 @@ use std::collections::{HashMap, HashSet};
 use std::path::Path;
 
 use elasticlunr::{Index, IndexBuilder};
+use once_cell::sync::Lazy;
 use pulldown_cmark::*;
 
 use crate::book::{Book, BookItem};
@@ -10,7 +11,7 @@ use crate::config::Search;
 use crate::errors::*;
 use crate::theme::searcher;
 use crate::utils;
-
+use log::{debug, warn};
 use serde::Serialize;
 
 const MAX_WORD_LENGTH_TO_INDEX: usize = 80;
@@ -137,9 +138,11 @@ fn render_item(
 
                 in_heading = true;
             }
-            Event::End(Tag::Heading(i, ..)) if i as u32 <= max_section_depth => {
+            Event::End(Tag::Heading(i, id, _classes)) if i as u32 <= max_section_depth => {
                 in_heading = false;
-                section_id = Some(utils::unique_id_from_content(&heading, &mut id_counter));
+                section_id = id
+                    .map(|id| id.to_string())
+                    .or_else(|| Some(utils::unique_id_from_content(&heading, &mut id_counter)));
                 breadcrumbs.push(heading.clone());
             }
             Event::Start(Tag::FootnoteDefinition(name)) => {
@@ -266,21 +269,19 @@ fn write_to_json(index: Index, search_config: &Search, doc_urls: Vec<String>) ->
 }
 
 fn clean_html(html: &str) -> String {
-    lazy_static! {
-        static ref AMMONIA: ammonia::Builder<'static> = {
-            let mut clean_content = HashSet::new();
-            clean_content.insert("script");
-            clean_content.insert("style");
-            let mut builder = ammonia::Builder::new();
-            builder
-                .tags(HashSet::new())
-                .tag_attributes(HashMap::new())
-                .generic_attributes(HashSet::new())
-                .link_rel(None)
-                .allowed_classes(HashMap::new())
-                .clean_content_tags(clean_content);
-            builder
-        };
-    }
+    static AMMONIA: Lazy<ammonia::Builder<'static>> = Lazy::new(|| {
+        let mut clean_content = HashSet::new();
+        clean_content.insert("script");
+        clean_content.insert("style");
+        let mut builder = ammonia::Builder::new();
+        builder
+            .tags(HashSet::new())
+            .tag_attributes(HashMap::new())
+            .generic_attributes(HashSet::new())
+            .link_rel(None)
+            .allowed_classes(HashMap::new())
+            .clean_content_tags(clean_content);
+        builder
+    });
     AMMONIA.clean(html).to_string()
 }

src/renderer/markdown_renderer.rs

@@ -2,7 +2,7 @@ use crate::book::BookItem;
 use crate::errors::*;
 use crate::renderer::{RenderContext, Renderer};
 use crate::utils;
-
+use log::trace;
 use std::fs;
 
 #[derive(Default)]
@@ -37,14 +37,14 @@ impl Renderer for MarkdownRenderer {
                 if !ch.is_draft_chapter() {
                     utils::fs::write_file(
                         &ctx.destination,
-                        &ch.path.as_ref().expect("Checked path exists before"),
+                        ch.path.as_ref().expect("Checked path exists before"),
                         ch.content.as_bytes(),
                     )?;
                 }
             }
         }
 
-        fs::create_dir_all(&destination)
+        fs::create_dir_all(destination)
             .with_context(|| "Unexpected error when constructing destination path")?;
 
         Ok(())

src/renderer/mod.rs

@@ -27,6 +27,7 @@ use std::process::{Command, Stdio};
 use crate::book::Book;
 use crate::config::Config;
 use crate::errors::*;
+use log::{error, info, trace, warn};
 use toml::Value;
 
 use serde::{Deserialize, Serialize};

src/theme/book.js

@@ -4,14 +4,16 @@
 window.onunload = function () { };
 
 // Global variable, shared between modules
-function playground_text(playground) {
+function playground_text(playground, hidden = true) {
     let code_block = playground.querySelector("code");
 
     if (window.ace && code_block.classList.contains("editable")) {
         let editor = window.ace.edit(code_block);
         return editor.getValue();
-    } else {
+    } else if (hidden) {
         return code_block.textContent;
+    } else {
+        return code_block.innerText;
     }
 }
 
@@ -66,7 +68,7 @@ function playground_text(playground) {
     }
 
     // updates the visibility of play button based on `no_run` class and
-    // used crates vs ones available on http://play.rust-lang.org
+    // used crates vs ones available on https://play.rust-lang.org
     function update_play_button(pre_block, playground_crates) {
         var play_button = pre_block.querySelector(".play-button");
 
@@ -166,7 +168,6 @@ function playground_text(playground) {
             .filter(function (node) {return node.classList.contains("editable"); })
             .forEach(function (block) { block.classList.remove('language-rust'); });
 
-        Array
         code_nodes
             .filter(function (node) {return !node.classList.contains("editable"); })
             .forEach(function (block) { hljs.highlightBlock(block); });
@@ -178,7 +179,7 @@ function playground_text(playground) {
     // even if highlighting doesn't apply
     code_nodes.forEach(function (block) { block.classList.add('hljs'); });
 
-    Array.from(document.querySelectorAll("code.language-rust")).forEach(function (block) {
+    Array.from(document.querySelectorAll("code.hljs")).forEach(function (block) {
 
         var lines = Array.from(block.querySelectorAll('.boring'));
         // If no lines were hidden, return
@@ -300,6 +301,13 @@ function playground_text(playground) {
         themePopup.querySelector("button#" + get_theme()).focus();
     }
 
+    function updateThemeSelected() {
+        themePopup.querySelectorAll('.theme-selected').forEach(function (el) {
+            el.classList.remove('theme-selected');
+        });
+        themePopup.querySelector("button#" + get_theme()).classList.add('theme-selected');
+    }
+
     function hideThemes() {
         themePopup.style.display = 'none';
         themeToggleButton.setAttribute('aria-expanded', false);
@@ -338,7 +346,7 @@ function playground_text(playground) {
         }
 
         setTimeout(function () {
-            themeColorMetaTag.content = getComputedStyle(document.body).backgroundColor;
+            themeColorMetaTag.content = getComputedStyle(document.documentElement).backgroundColor;
         }, 1);
 
         if (window.ace && window.editors) {
@@ -355,6 +363,7 @@ function playground_text(playground) {
 
         html.classList.remove(previousTheme);
         html.classList.add(theme);
+        updateThemeSelected();
     }
 
     // Set theme
@@ -432,7 +441,7 @@ function playground_text(playground) {
 })();
 
 (function sidebar() {
-    var html = document.querySelector("html");
+    var body = document.querySelector("body");
     var sidebar = document.getElementById("sidebar");
     var sidebarLinks = document.querySelectorAll('#sidebar a');
     var sidebarToggleButton = document.getElementById("sidebar-toggle");
@@ -440,8 +449,8 @@ function playground_text(playground) {
     var firstContact = null;
 
     function showSidebar() {
-        html.classList.remove('sidebar-hidden')
-        html.classList.add('sidebar-visible');
+        body.classList.remove('sidebar-hidden')
+        body.classList.add('sidebar-visible');
         Array.from(sidebarLinks).forEach(function (link) {
             link.setAttribute('tabIndex', 0);
         });
@@ -462,8 +471,8 @@ function playground_text(playground) {
     });
 
     function hideSidebar() {
-        html.classList.remove('sidebar-visible')
-        html.classList.add('sidebar-hidden');
+        body.classList.remove('sidebar-visible')
+        body.classList.add('sidebar-hidden');
         Array.from(sidebarLinks).forEach(function (link) {
             link.setAttribute('tabIndex', -1);
         });
@@ -474,14 +483,14 @@ function playground_text(playground) {
 
     // Toggle sidebar
     sidebarToggleButton.addEventListener('click', function sidebarToggle() {
-        if (html.classList.contains("sidebar-hidden")) {
+        if (body.classList.contains("sidebar-hidden")) {
             var current_width = parseInt(
                 document.documentElement.style.getPropertyValue('--sidebar-width'), 10);
             if (current_width < 150) {
                 document.documentElement.style.setProperty('--sidebar-width', '150px');
             }
             showSidebar();
-        } else if (html.classList.contains("sidebar-visible")) {
+        } else if (body.classList.contains("sidebar-visible")) {
             hideSidebar();
         } else {
             if (getComputedStyle(sidebar)['transform'] === 'none') {
@@ -497,14 +506,14 @@ function playground_text(playground) {
     function initResize(e) {
         window.addEventListener('mousemove', resize, false);
         window.addEventListener('mouseup', stopResize, false);
-        html.classList.add('sidebar-resizing');
+        body.classList.add('sidebar-resizing');
     }
     function resize(e) {
         var pos = (e.clientX - sidebar.offsetLeft);
         if (pos < 20) {
             hideSidebar();
         } else {
-            if (html.classList.contains("sidebar-hidden")) {
+            if (body.classList.contains("sidebar-hidden")) {
                 showSidebar();
             }
             pos = Math.min(pos, window.innerWidth - 100);
@@ -513,7 +522,7 @@ function playground_text(playground) {
     }
     //on mouseup remove windows functions mousemove & mouseup
     function stopResize(e) {
-        html.classList.remove('sidebar-resizing');
+        body.classList.remove('sidebar-resizing');
         window.removeEventListener('mousemove', resize, false);
         window.removeEventListener('mouseup', stopResize, false);
     }
@@ -542,33 +551,41 @@ function playground_text(playground) {
             firstContact = null;
         }
     }, { passive: true });
-
-    // Scroll sidebar to current active section
-    var activeSection = document.getElementById("sidebar").querySelector(".active");
-    if (activeSection) {
-        // https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
-        activeSection.scrollIntoView({ block: 'center' });
-    }
 })();
 
 (function chapterNavigation() {
     document.addEventListener('keydown', function (e) {
         if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) { return; }
         if (window.search && window.search.hasFocus()) { return; }
+        var html = document.querySelector('html');
 
+        function next() {
+            var nextButton = document.querySelector('.nav-chapters.next');
+            if (nextButton) {
+                window.location.href = nextButton.href;
+            }
+        }
+        function prev() {
+            var previousButton = document.querySelector('.nav-chapters.previous');
+            if (previousButton) {
+                window.location.href = previousButton.href;
+            }
+        }
         switch (e.key) {
             case 'ArrowRight':
                 e.preventDefault();
-                var nextButton = document.querySelector('.nav-chapters.next');
-                if (nextButton) {
-                    window.location.href = nextButton.href;
+                if (html.dir == 'rtl') {
+                    prev();
+                } else {
+                    next();
                 }
                 break;
             case 'ArrowLeft':
                 e.preventDefault();
-                var previousButton = document.querySelector('.nav-chapters.previous');
-                if (previousButton) {
-                    window.location.href = previousButton.href;
+                if (html.dir == 'rtl') {
+                    next();
+                } else {
+                    prev();
                 }
                 break;
         }
@@ -592,7 +609,7 @@ function playground_text(playground) {
         text: function (trigger) {
             hideTooltip(trigger);
             let playground = trigger.closest("pre");
-            return playground_text(playground);
+            return playground_text(playground, false);
         }
     });
 
@@ -667,13 +684,14 @@ function playground_text(playground) {
         }, { passive: true });
     })();
     (function controllBorder() {
-        menu.classList.remove('bordered');
-        document.addEventListener('scroll', function () {
+        function updateBorder() {
             if (menu.offsetTop === 0) {
                 menu.classList.remove('bordered');
             } else {
                 menu.classList.add('bordered');
             }
-        }, { passive: true });
+        }
+        updateBorder();
+        document.addEventListener('scroll', updateBorder, { passive: true });
     })();
 })();

src/theme/css/chrome.css

@@ -2,12 +2,6 @@
 
 @import 'variables.css';
 
-::-webkit-scrollbar {
-    background: var(--bg);
-}
-::-webkit-scrollbar-thumb {
-    background: var(--scrollbar);
-}
 html {
     scrollbar-color: var(--scrollbar) var(--bg);
 }
@@ -18,6 +12,19 @@ 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,
@@ -30,9 +37,9 @@ 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,
@@ -49,7 +56,7 @@ 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 +93,7 @@ a > .hljs {
     display: flex;
     margin: 0 5px;
 }
-.no-js .left-buttons {
+.no-js .left-buttons button {
     display: none;
 }
 
@@ -153,7 +160,7 @@ a > .hljs {
 }
 
 .nav-wrapper {
-    margin-top: 50px;
+    margin-block-start: 50px;
     display: none;
 }
 
@@ -166,23 +173,34 @@ 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 */
@@ -229,7 +247,7 @@ pre > .buttons :hover {
     background-color: var(--theme-hover);
 }
 pre > .buttons i {
-    margin-left: 8px;
+    margin-inline-start: 8px;
 }
 pre > .buttons button {
     cursor: inherit;
@@ -252,7 +270,7 @@ pre > .buttons button {
         padding: 0.3rem 1rem;
     }
 }
-code {
+pre > code {
     padding: 1rem;
 }
 
@@ -266,7 +284,7 @@ code {
 }
 
 pre > .result {
-    margin-top: 10px;
+    margin-block-start: 10px;
 }
 
 /* Search */
@@ -277,8 +295,14 @@ 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;
@@ -290,14 +314,17 @@ 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);
@@ -313,20 +340,23 @@ 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;
@@ -339,7 +369,10 @@ 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 {
@@ -362,12 +395,14 @@ ul#searchresults span.teaser em {
     background-color: var(--sidebar-bg);
     color: var(--sidebar-fg);
 }
+[dir=rtl] .sidebar { left: unset; right: 0; }
 .sidebar-resizing {
     -moz-user-select: none;
     -webkit-user-select: none;
     -ms-user-select: none;
     user-select: none;
 }
+.no-js .sidebar,
 .js:not(.sidebar-resizing) .sidebar {
     transition: transform 0.3s; /* Animation: slide away */
 }
@@ -391,12 +426,18 @@ ul#searchresults span.teaser em {
     top: 0;
     bottom: 0;
 }
+[dir=rtl] .sidebar .sidebar-resize-handle { right:  unset; left: 0; }
 .js .sidebar .sidebar-resize-handle {
     cursor: col-resize;
     width: 5px;
 }
-.sidebar-hidden .sidebar {
+/* sidebar-hidden */
+#sidebar-toggle-anchor:not(:checked) ~ .sidebar {
     transform: translateX(calc(0px - var(--sidebar-width)));
+    z-index: -1;
+}
+[dir=rtl] #sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+    transform: translateX(var(--sidebar-width));
 }
 .sidebar::-webkit-scrollbar {
     background: var(--sidebar-bg);
@@ -405,19 +446,26 @@ ul#searchresults span.teaser em {
     background: var(--scrollbar);
 }
 
-.sidebar-visible .page-wrapper {
+/* sidebar-visible */
+#sidebar-toggle-anchor:checked ~ .page-wrapper {
     transform: translateX(var(--sidebar-width));
 }
+[dir=rtl] #sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: translateX(calc(0px - var(--sidebar-width)));
+}
 @media only screen and (min-width: 620px) {
-    .sidebar-visible .page-wrapper {
+    #sidebar-toggle-anchor:checked ~ .page-wrapper {
+        transform: none;
+        margin-inline-start: var(--sidebar-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;
 }
 
@@ -447,7 +495,7 @@ 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;
@@ -464,7 +512,7 @@ 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 {
@@ -487,7 +535,7 @@ ul#searchresults span.teaser em {
 
 .section {
     list-style: none outside none;
-    padding-left: 20px;
+    padding-inline-start: 20px;
     line-height: 1.9em;
 }
 
@@ -507,7 +555,10 @@ 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);
 }
@@ -515,10 +566,10 @@ 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;
@@ -527,8 +578,10 @@ 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/theme/css/general.css

@@ -5,6 +5,7 @@
 :root {
     /* Browser default font-size is 16px, this way 1 rem = 10px */
     font-size: 62.5%;
+    color-scheme: var(--color-scheme);
 }
 
 html {
@@ -22,8 +23,9 @@ body {
 }
 
 code {
-    font-family: "Source Code Pro", Consolas, "Ubuntu Mono", Menlo, "DejaVu Sans Mono", monospace, monospace !important;
-    font-size: 0.875em; /* please adjust the ace font size accordingly in editor.js */
+    font-family: var(--mono-font) !important;
+    font-size: var(--code-font-size);
+    direction: ltr !important;
 }
 
 /* make long words/inline code not x overflow */
@@ -47,13 +49,13 @@ h1 code, h2 code, h3 code, h4 code, h5 code, h6 code {
 .hide-boring .boring { display: none; }
 .hidden { display: none !important; }
 
-h2, h3 { margin-top: 2.5em; }
-h4, h5 { margin-top: 2em; }
+h2, h3 { margin-block-start: 2.5em; }
+h4, h5 { margin-block-start: 2em; }
 
 .header + .header h3,
 .header + .header h4,
 .header + .header h5 {
-    margin-top: 1em;
+    margin-block-start: 1em;
 }
 
 h1:target::before,
@@ -64,7 +66,7 @@ h5:target::before,
 h6:target::before {
     display: inline-block;
     content: "»";
-    margin-left: -30px;
+    margin-inline-start: -30px;
     width: 30px;
 }
 
@@ -73,28 +75,34 @@ h6:target::before {
    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-top: calc(0px - var(--menu-bar-height)); /* Compensate for the #menu-bar-hover-placeholder */
+    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-left: auto;
-    margin-right: auto;
+    margin-inline-start: auto;
+    margin-inline-end: auto;
     max-width: var(--content-max-width);
 }
 .content p { line-height: 1.45em; }
@@ -144,14 +152,49 @@ blockquote {
     padding: 0 20px;
     color: var(--fg);
     background-color: var(--quote-bg);
-    border-top: .1em solid var(--quote-border);
-    border-bottom: .1em solid var(--quote-border);
+    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;
+}
 
 :not(.footnote-definition) + .footnote-definition,
 .footnote-definition + :not(.footnote-definition) {
-    margin-top: 2em;
+    margin-block-start: 2em;
 }
 .footnote-definition {
     font-size: 0.9em;

src/theme/css/print.css

@@ -8,7 +8,7 @@
 
 #page-wrapper.page-wrapper {
     transform: none;
-    margin-left: 0px;
+    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/theme/css/variables.css

@@ -6,6 +6,8 @@
     --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 +38,8 @@
     --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 +52,8 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #252932;
     --search-mark-bg: #e3b171;
+
+    --color-scheme: dark;
 }
 
 .coal {
@@ -76,6 +82,8 @@
     --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%);
@@ -88,6 +96,8 @@
     --searchresults-border-color: #98a3ad;
     --searchresults-li-bg: #2b2b2f;
     --search-mark-bg: #355c7d;
+
+    --color-scheme: dark;
 }
 
 .light {
@@ -116,6 +126,8 @@
     --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 +140,8 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #e4f2fe;
     --search-mark-bg: #a2cff5;
+
+    --color-scheme: light;
 }
 
 .navy {
@@ -156,6 +170,8 @@
     --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 +184,8 @@
     --searchresults-border-color: #5c5c68;
     --searchresults-li-bg: #242430;
     --search-mark-bg: #a2cff5;
+
+    --color-scheme: dark;
 }
 
 .rust {
@@ -196,6 +214,8 @@
     --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%);
@@ -208,6 +228,8 @@
     --searchresults-border-color: #888;
     --searchresults-li-bg: #dec2a2;
     --search-mark-bg: #e69f67;
+
+    --color-scheme: light;
 }
 
 @media (prefers-color-scheme: dark) {
@@ -237,6 +259,8 @@
         --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%);

src/theme/index.hbs

@@ -1,11 +1,11 @@
 <!DOCTYPE HTML>
-<html lang="{{ language }}" class="sidebar-visible no-js {{ default_theme }}">
+<html lang="{{ language }}" class="{{ default_theme }}" dir="{{ text_direction }}">
     <head>
         <!-- Book generated using mdBook -->
         <meta charset="UTF-8">
         <title>{{ title }}</title>
         {{#if is_print }}
-        <meta name="robots" content="noindex" />
+        <meta name="robots" content="noindex">
         {{/if}}
         {{#if base_url}}
         <base href="{{ base_url }}">
@@ -15,10 +15,9 @@
         <!-- Custom HTML head -->
         {{> head}}
 
-        <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
         <meta name="description" content="{{ description }}">
         <meta name="viewport" content="width=device-width, initial-scale=1">
-        <meta name="theme-color" content="#ffffff" />
+        <meta name="theme-color" content="#ffffff">
 
         {{#if favicon_svg}}
         <link rel="icon" href="{{ path_to_root }}favicon.svg">
@@ -51,18 +50,19 @@
 
         {{#if mathjax_support}}
         <!-- MathJax -->
-        <script async type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
+        <script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
         {{/if}}
     </head>
-    <body>
+    <body class="sidebar-visible no-js">
+    <div id="body-container">
         <!-- Provide site root to javascript -->
-        <script type="text/javascript">
+        <script>
             var path_to_root = "{{ path_to_root }}";
             var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "{{ preferred_dark_theme }}" : "{{ default_theme }}";
         </script>
 
         <!-- Work around some values being stored in localStorage wrapped in quotes -->
-        <script type="text/javascript">
+        <script>
             try {
                 var theme = localStorage.getItem('mdbook-theme');
                 var sidebar = localStorage.getItem('mdbook-sidebar');
@@ -78,27 +78,34 @@
         </script>
 
         <!-- Set the theme before any content is loaded, prevents flash -->
-        <script type="text/javascript">
+        <script>
             var theme;
             try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
             if (theme === null || theme === undefined) { theme = default_theme; }
             var html = document.querySelector('html');
-            html.classList.remove('no-js')
             html.classList.remove('{{ default_theme }}')
             html.classList.add(theme);
-            html.classList.add('js');
+            var body = document.querySelector('body');
+            body.classList.remove('no-js')
+            body.classList.add('js');
         </script>
 
+        <input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
+
         <!-- Hide / unhide sidebar before it is displayed -->
-        <script type="text/javascript">
-            var html = document.querySelector('html');
-            var sidebar = 'hidden';
+        <script>
+            var body = document.querySelector('body');
+            var sidebar = null;
+            var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
             if (document.body.clientWidth >= 1080) {
                 try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
                 sidebar = sidebar || 'visible';
+            } else {
+                sidebar = 'hidden';
             }
-            html.classList.remove('sidebar-visible');
-            html.classList.add("sidebar-" + sidebar);
+            sidebar_toggle.checked = sidebar === 'visible';
+            body.classList.remove('sidebar-visible');
+            body.classList.add("sidebar-" + sidebar);
         </script>
 
         <nav id="sidebar" class="sidebar" aria-label="Table of contents">
@@ -108,25 +115,47 @@
             <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
         </nav>
 
+        <!-- Track and set sidebar scroll position -->
+        <script>
+            var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
+            sidebarScrollbox.addEventListener('click', function(e) {
+                if (e.target.tagName === 'A') {
+                    sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
+                }
+            }, { passive: true });
+            var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
+            sessionStorage.removeItem('sidebar-scroll');
+            if (sidebarScrollTop) {
+                // preserve sidebar scroll position when navigating via links within sidebar
+                sidebarScrollbox.scrollTop = sidebarScrollTop;
+            } else {
+                // scroll sidebar to current active section when navigating via "next/previous chapter" buttons
+                var activeSection = document.querySelector('#sidebar .active');
+                if (activeSection) {
+                    activeSection.scrollIntoView({ block: 'center' });
+                }
+            }
+        </script>
+
         <div id="page-wrapper" class="page-wrapper">
 
             <div class="page">
                 {{> header}}
                 <div id="menu-bar-hover-placeholder"></div>
-                <div id="menu-bar" class="menu-bar sticky bordered">
+                <div id="menu-bar" class="menu-bar sticky">
                     <div class="left-buttons">
-                        <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
+                        <label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
                             <i class="fa fa-bars"></i>
-                        </button>
+                        </label>
                         <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
                             <i class="fa fa-paint-brush"></i>
                         </button>
                         <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
-                            <li role="none"><button role="menuitem" class="theme" id="light">{{ theme_option "Light" }}</button></li>
-                            <li role="none"><button role="menuitem" class="theme" id="rust">{{ theme_option "Rust" }}</button></li>
-                            <li role="none"><button role="menuitem" class="theme" id="coal">{{ theme_option "Coal" }}</button></li>
-                            <li role="none"><button role="menuitem" class="theme" id="navy">{{ theme_option "Navy" }}</button></li>
-                            <li role="none"><button role="menuitem" class="theme" id="ayu">{{ theme_option "Ayu" }}</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
                         </ul>
                         {{#if search_enabled}}
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
@@ -171,7 +200,7 @@
                 {{/if}}
 
                 <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
-                <script type="text/javascript">
+                <script>
                     document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
                     document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
                     Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
@@ -193,7 +222,7 @@
                         {{/previous}}
 
                         {{#next}}
-                            <a rel="next" href="{{ path_to_root }}{{link}}" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                            <a rel="next prefetch" href="{{ path_to_root }}{{link}}" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                                 <i class="fa fa-angle-right"></i>
                             </a>
                         {{/next}}
@@ -211,7 +240,7 @@
                 {{/previous}}
 
                 {{#next}}
-                    <a rel="next" href="{{ path_to_root }}{{link}}" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                    <a rel="next prefetch" href="{{ path_to_root }}{{link}}" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                         <i class="fa fa-angle-right"></i>
                     </a>
                 {{/next}}
@@ -221,7 +250,7 @@
 
         {{#if live_reload_endpoint}}
         <!-- Livereload script (if served using the cli tool) -->
-        <script type="text/javascript">
+        <script>
             const wsProtocol = location.protocol === 'https:' ? 'wss:' : 'ws:';
             const wsAddress = wsProtocol + "//" + location.host + "/" + "{{{live_reload_endpoint}}}";
             const socket = new WebSocket(wsAddress);
@@ -240,7 +269,7 @@
 
         {{#if google_analytics}}
         <!-- Google Analytics Tag -->
-        <script type="text/javascript">
+        <script>
             var localAddrs = ["localhost", "127.0.0.1", ""];
 
             // make sure we don't activate google analytics if the developer is
@@ -258,43 +287,43 @@
         {{/if}}
 
         {{#if playground_line_numbers}}
-        <script type="text/javascript">
+        <script>
             window.playground_line_numbers = true;
         </script>
         {{/if}}
 
         {{#if playground_copyable}}
-        <script type="text/javascript">
+        <script>
             window.playground_copyable = true;
         </script>
         {{/if}}
 
         {{#if playground_js}}
-        <script src="{{ path_to_root }}ace.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}editor.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}mode-rust.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}theme-dawn.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}theme-tomorrow_night.js" type="text/javascript" charset="utf-8"></script>
+        <script src="{{ path_to_root }}ace.js"></script>
+        <script src="{{ path_to_root }}editor.js"></script>
+        <script src="{{ path_to_root }}mode-rust.js"></script>
+        <script src="{{ path_to_root }}theme-dawn.js"></script>
+        <script src="{{ path_to_root }}theme-tomorrow_night.js"></script>
         {{/if}}
 
         {{#if search_js}}
-        <script src="{{ path_to_root }}elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}mark.min.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}searcher.js" type="text/javascript" charset="utf-8"></script>
+        <script src="{{ path_to_root }}elasticlunr.min.js"></script>
+        <script src="{{ path_to_root }}mark.min.js"></script>
+        <script src="{{ path_to_root }}searcher.js"></script>
         {{/if}}
 
-        <script src="{{ path_to_root }}clipboard.min.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}highlight.js" type="text/javascript" charset="utf-8"></script>
-        <script src="{{ path_to_root }}book.js" type="text/javascript" charset="utf-8"></script>
+        <script src="{{ path_to_root }}clipboard.min.js"></script>
+        <script src="{{ path_to_root }}highlight.js"></script>
+        <script src="{{ path_to_root }}book.js"></script>
 
         <!-- Custom JS scripts -->
         {{#each additional_js}}
-        <script type="text/javascript" src="{{ ../path_to_root }}{{this}}"></script>
+        <script src="{{ ../path_to_root }}{{this}}"></script>
         {{/each}}
 
         {{#if is_print}}
         {{#if mathjax_support}}
-        <script type="text/javascript">
+        <script>
         window.addEventListener('load', function() {
             MathJax.Hub.Register.StartupHook('End', function() {
                 window.setTimeout(window.print, 100);
@@ -302,7 +331,7 @@
         });
         </script>
         {{else}}
-        <script type="text/javascript">
+        <script>
         window.addEventListener('load', function() {
             window.setTimeout(window.print, 100);
         });
@@ -310,5 +339,6 @@
         {{/if}}
         {{/if}}
 
+    </div>
     </body>
 </html>

src/theme/mod.rs

@@ -9,10 +9,10 @@ pub mod searcher;
 
 use std::fs::File;
 use std::io::Read;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use crate::errors::*;
-
+use log::warn;
 pub static INDEX: &[u8] = include_bytes!("index.hbs");
 pub static HEAD: &[u8] = include_bytes!("head.hbs");
 pub static REDIRECT: &[u8] = include_bytes!("redirect.hbs");
@@ -54,6 +54,8 @@ pub struct Theme {
     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>,
@@ -104,7 +106,7 @@ 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 +123,29 @@ 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();
@@ -153,6 +178,8 @@ impl Default for Theme {
             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(),
@@ -209,10 +236,10 @@ mod tests {
             "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 +250,7 @@ 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 {
@@ -240,6 +268,8 @@ mod tests {
             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(),

src/theme/redirect.hbs

@@ -3,8 +3,8 @@
   <head>
     <meta charset="utf-8">
     <title>Redirecting...</title>
-    <meta http-equiv="refresh" content="0;URL='{{url}}'">
-    <meta rel="canonical" href="{{url}}">
+    <meta http-equiv="refresh" content="0; URL={{url}}">
+    <link rel="canonical" href="{{url}}">
   </head>
   <body>
       <p>Redirecting to... <a href="{{url}}">{{url}}</a>.</p>

src/theme/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 {

src/utils/fs.rs

@@ -1,4 +1,5 @@
 use crate::errors::*;
+use log::{debug, trace};
 use std::convert::Into;
 use std::fs::{self, File};
 use std::io::Write;
@@ -37,7 +38,6 @@ pub fn write_file<P: AsRef<Path>>(build_dir: &Path, filename: P, content: &[u8])
 /// Consider [submitting a new issue](https://github.com/rust-lang/mdBook/issues)
 /// or a [pull-request](https://github.com/rust-lang/mdBook/pulls) to improve it.
 pub fn path_to_root<P: Into<PathBuf>>(path: P) -> String {
-    debug!("path_to_root");
     // Remove filename and add "../" for every directory
 
     path.into()
@@ -166,7 +166,7 @@ pub fn copy_files_except_ext(
                         .expect("a file should have a file name...")
                 )
             );
-            fs::copy(
+            copy(
                 entry.path(),
                 &to.join(
                     entry
@@ -180,6 +180,62 @@ pub fn copy_files_except_ext(
     Ok(())
 }
 
+/// Copies a file.
+fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> Result<()> {
+    let from = from.as_ref();
+    let to = to.as_ref();
+    return copy_inner(from, to)
+        .with_context(|| format!("failed to copy `{}` to `{}`", from.display(), to.display()));
+
+    // This is a workaround for an issue with the macOS file watcher.
+    // Rust's `std::fs::copy` function uses `fclonefileat`, which creates
+    // clones on APFS. Unfortunately fs events seem to trigger on both
+    // sides of the clone, and there doesn't seem to be a way to differentiate
+    // which side it is.
+    // https://github.com/notify-rs/notify/issues/465#issuecomment-1657261035
+    // contains more information.
+    //
+    // This is essentially a copy of the simple copy code path in Rust's
+    // standard library.
+    #[cfg(target_os = "macos")]
+    fn copy_inner(from: &Path, to: &Path) -> Result<()> {
+        use std::fs::OpenOptions;
+        use std::os::unix::fs::{OpenOptionsExt, PermissionsExt};
+
+        let mut reader = File::open(from)?;
+        let metadata = reader.metadata()?;
+        if !metadata.is_file() {
+            anyhow::bail!(
+                "expected a file, `{}` appears to be {:?}",
+                from.display(),
+                metadata.file_type()
+            );
+        }
+        let perm = metadata.permissions();
+        let mut writer = OpenOptions::new()
+            .mode(perm.mode())
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(to)?;
+        let writer_metadata = writer.metadata()?;
+        if writer_metadata.is_file() {
+            // Set the correct file permissions, in case the file already existed.
+            // Don't set the permissions on already existing non-files like
+            // pipes/FIFOs or device nodes.
+            writer.set_permissions(perm)?;
+        }
+        std::io::copy(&mut reader, &mut writer)?;
+        Ok(())
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    fn copy_inner(from: &Path, to: &Path) -> Result<()> {
+        fs::copy(from, to)?;
+        Ok(())
+    }
+}
+
 pub fn get_404_output_file(input_404: &Option<String>) -> String {
     input_404
         .as_ref()
@@ -210,39 +266,36 @@ mod tests {
         };
 
         // Create a couple of files
-        if let Err(err) = fs::File::create(&tmp.path().join("file.txt")) {
+        if let Err(err) = fs::File::create(tmp.path().join("file.txt")) {
             panic!("Could not create file.txt: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("file.md")) {
+        if let Err(err) = fs::File::create(tmp.path().join("file.md")) {
             panic!("Could not create file.md: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("file.png")) {
+        if let Err(err) = fs::File::create(tmp.path().join("file.png")) {
             panic!("Could not create file.png: {}", err);
         }
-        if let Err(err) = fs::create_dir(&tmp.path().join("sub_dir")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("sub_dir")) {
             panic!("Could not create sub_dir: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("sub_dir/file.png")) {
+        if let Err(err) = fs::File::create(tmp.path().join("sub_dir/file.png")) {
             panic!("Could not create sub_dir/file.png: {}", err);
         }
-        if let Err(err) = fs::create_dir(&tmp.path().join("sub_dir_exists")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("sub_dir_exists")) {
             panic!("Could not create sub_dir_exists: {}", err);
         }
-        if let Err(err) = fs::File::create(&tmp.path().join("sub_dir_exists/file.txt")) {
+        if let Err(err) = fs::File::create(tmp.path().join("sub_dir_exists/file.txt")) {
             panic!("Could not create sub_dir_exists/file.txt: {}", err);
         }
-        if let Err(err) = symlink(
-            &tmp.path().join("file.png"),
-            &tmp.path().join("symlink.png"),
-        ) {
+        if let Err(err) = symlink(tmp.path().join("file.png"), tmp.path().join("symlink.png")) {
             panic!("Could not symlink file.png: {}", err);
         }
 
         // Create output dir
-        if let Err(err) = fs::create_dir(&tmp.path().join("output")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("output")) {
             panic!("Could not create output: {}", err);
         }
-        if let Err(err) = fs::create_dir(&tmp.path().join("output/sub_dir_exists")) {
+        if let Err(err) = fs::create_dir(tmp.path().join("output/sub_dir_exists")) {
             panic!("Could not create output/sub_dir_exists: {}", err);
         }
 
@@ -253,22 +306,22 @@ mod tests {
         }
 
         // Check if the correct files where created
-        if !(&tmp.path().join("output/file.txt")).exists() {
+        if !tmp.path().join("output/file.txt").exists() {
             panic!("output/file.txt should exist")
         }
-        if (&tmp.path().join("output/file.md")).exists() {
+        if tmp.path().join("output/file.md").exists() {
             panic!("output/file.md should not exist")
         }
-        if !(&tmp.path().join("output/file.png")).exists() {
+        if !tmp.path().join("output/file.png").exists() {
             panic!("output/file.png should exist")
         }
-        if !(&tmp.path().join("output/sub_dir/file.png")).exists() {
+        if !tmp.path().join("output/sub_dir/file.png").exists() {
             panic!("output/sub_dir/file.png should exist")
         }
-        if !(&tmp.path().join("output/sub_dir_exists/file.txt")).exists() {
+        if !tmp.path().join("output/sub_dir_exists/file.txt").exists() {
             panic!("output/sub_dir/file.png should exist")
         }
-        if !(&tmp.path().join("output/symlink.png")).exists() {
+        if !tmp.path().join("output/symlink.png").exists() {
             panic!("output/symlink.png should exist")
         }
     }

src/utils/mod.rs

@@ -4,9 +4,10 @@ pub mod fs;
 mod string;
 pub(crate) mod toml_ext;
 use crate::errors::Error;
-use regex::Regex;
-
+use log::error;
+use once_cell::sync::Lazy;
 use pulldown_cmark::{html, CodeBlockKind, CowStr, Event, Options, Parser, Tag};
+use regex::Regex;
 
 use std::borrow::Cow;
 use std::collections::HashMap;
@@ -20,9 +21,7 @@ pub use self::string::{
 
 /// Replaces multiple consecutive whitespace characters with a single space character.
 pub fn collapse_whitespace(text: &str) -> Cow<'_, str> {
-    lazy_static! {
-        static ref RE: Regex = Regex::new(r"\s\s+").unwrap();
-    }
+    static RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"\s\s+").unwrap());
     RE.replace_all(text, " ")
 }
 
@@ -51,9 +50,7 @@ pub fn id_from_content(content: &str) -> String {
     let mut content = content.to_string();
 
     // Skip any tags or html-encoded stuff
-    lazy_static! {
-        static ref HTML: Regex = Regex::new(r"(<.*?>)").unwrap();
-    }
+    static HTML: Lazy<Regex> = Lazy::new(|| Regex::new(r"(<.*?>)").unwrap());
     content = HTML.replace_all(&content, "").into();
     const REPL_SUB: &[&str] = &["&lt;", "&gt;", "&amp;", "&#39;", "&quot;"];
     for sub in REPL_SUB {
@@ -96,10 +93,9 @@ pub fn unique_id_from_content(content: &str, id_counter: &mut HashMap<String, us
 /// None. Ideally, print page links would link to anchors on the print page,
 /// but that is very difficult.
 fn adjust_links<'a>(event: Event<'a>, path: Option<&Path>) -> Event<'a> {
-    lazy_static! {
-        static ref SCHEME_LINK: Regex = Regex::new(r"^[a-z][a-z0-9+.-]*:").unwrap();
-        static ref MD_LINK: Regex = Regex::new(r"(?P<link>.*)\.md(?P<anchor>#.*)?").unwrap();
-    }
+    static SCHEME_LINK: Lazy<Regex> = Lazy::new(|| Regex::new(r"^[a-z][a-z0-9+.-]*:").unwrap());
+    static MD_LINK: Lazy<Regex> =
+        Lazy::new(|| Regex::new(r"(?P<link>.*)\.md(?P<anchor>#.*)?").unwrap());
 
     fn fix<'a>(dest: CowStr<'a>, path: Option<&Path>) -> CowStr<'a> {
         if dest.starts_with('#') {
@@ -152,10 +148,8 @@ fn adjust_links<'a>(event: Event<'a>, path: Option<&Path>) -> Event<'a> {
         // There are dozens of HTML tags/attributes that contain paths, so
         // feel free to add more tags if desired; these are the only ones I
         // care about right now.
-        lazy_static! {
-            static ref HTML_LINK: Regex =
-                Regex::new(r#"(<(?:a|img) [^>]*?(?:src|href)=")([^"]+?)""#).unwrap();
-        }
+        static HTML_LINK: Lazy<Regex> =
+            Lazy::new(|| Regex::new(r#"(<(?:a|img) [^>]*?(?:src|href)=")([^"]+?)""#).unwrap());
 
         HTML_LINK
             .replace_all(&html, |caps: &regex::Captures<'_>| {
@@ -189,6 +183,7 @@ pub fn new_cmark_parser(text: &str, curly_quotes: bool) -> Parser<'_, '_> {
     opts.insert(Options::ENABLE_FOOTNOTES);
     opts.insert(Options::ENABLE_STRIKETHROUGH);
     opts.insert(Options::ENABLE_TASKLISTS);
+    opts.insert(Options::ENABLE_HEADING_ATTRIBUTES);
     if curly_quotes {
         opts.insert(Options::ENABLE_SMART_PUNCTUATION);
     }

src/utils/string.rs

@@ -1,3 +1,4 @@
+use once_cell::sync::Lazy;
 use regex::Regex;
 use std::ops::Bound::{Excluded, Included, Unbounded};
 use std::ops::RangeBounds;
@@ -23,10 +24,10 @@ pub fn take_lines<R: RangeBounds<usize>>(s: &str, range: R) -> String {
     }
 }
 
-lazy_static! {
-    static ref ANCHOR_START: Regex = Regex::new(r"ANCHOR:\s*(?P<anchor_name>[\w_-]+)").unwrap();
-    static ref ANCHOR_END: Regex = Regex::new(r"ANCHOR_END:\s*(?P<anchor_name>[\w_-]+)").unwrap();
-}
+static ANCHOR_START: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r"ANCHOR:\s*(?P<anchor_name>[\w_-]+)").unwrap());
+static ANCHOR_END: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r"ANCHOR_END:\s*(?P<anchor_name>[\w_-]+)").unwrap());
 
 /// Take anchored lines from a string.
 /// Lines containing anchor are ignored.

test_book/src/individual/code.md

@@ -10,7 +10,9 @@ This is a codeblock
 
 ---
 
-This line contains `inline code`
+This line contains `inline code` mixed with some other stuff. (LTR)
+
+ושורה זו מכילה `inline code` אבל עם טקסט בשפה שנכתבת מימין לשמאל. (RTL)
 
 ---
 

test_book/src/individual/heading.md

@@ -13,3 +13,9 @@
 ##### Really Small Heading
 
 ###### Is it even a heading anymore - heading
+
+## Custom id {#example-id}
+
+## Custom class {.class1 .class2}
+
+## Both id and class {#example-id2 .class1 .class2}

test_book/src/individual/image.md

@@ -4,19 +4,19 @@ For copyright and trademark information on these images, please check [rust-artw
 
 ## A 16x16 image
 
-![16x16 rust-lang logo](http://rust-lang.org/logos/rust-logo-16x16.png)
+![16x16 rust-lang logo](https://rust-lang.org/logos/rust-logo-16x16.png)
 
 ## A 32x32 image
 
-![32x32 rust-lang logo](http://rust-lang.org/logos/rust-logo-32x32-blk.png)
+![32x32 rust-lang logo](https://rust-lang.org/logos/rust-logo-32x32-blk.png)
 
 ## A 256x256 image
 
-![256x256 rust-lang logo](http://rust-lang.org/logos/rust-logo-256x256.png)
+![256x256 rust-lang logo](https://rust-lang.org/logos/rust-logo-256x256.png)
 
 ## A 512x512 image
 
-![512x512 rust-lang logo](http://rust-lang.org/logos/rust-logo-512x512-blk.png)
+![512x512 rust-lang logo](https://rust-lang.org/logos/rust-logo-512x512-blk.png)
 
 ## A large image
 

test_book/src/individual/mixed.md

@@ -27,9 +27,11 @@ fn main(){
 }
 ```
 
+<kbd>Ctrl</kbd> + <kbd>S</kbd> saves a file.
+
 A random image sprinkled in between
 
-![16x16 rust-lang logo](http://rust-lang.org/logos/rust-logo-16x16.png)
+![16x16 rust-lang logo](https://rust-lang.org/logos/rust-logo-16x16.png)
 
 ---
 
@@ -41,6 +43,7 @@ A random image sprinkled in between
   2. be
   3. `put`
   4. here?
+  5. **<kbd>Ctrl</kbd> + <kbd>S</kbd> saves a file.**
 
 | col1 | col2 | col 3 | col 4 | col 5 | col 6 |
 | ---- | ---- | ----- | ----- | ----- | ----- |

test_book/src/individual/strikethrough.md

@@ -1,5 +1,7 @@
 # Strikethrough
 
+~Single strike~
+
 ~~This is Striked~~
 
 ~~This is **strong**, _italic_ , **_both_** and striked~~

test_book/src/languages/highlight.md

@@ -57,7 +57,7 @@ _start:
 
 ## bash
 
-```
+```bash
 #!/bin/bash
 
 ###### CONFIG

tests/alternative_backends.rs

@@ -90,7 +90,7 @@ fn relative_command_path() {
             .set("output.html", toml::value::Table::new())
             .unwrap();
         config.set("output.myrenderer.command", cmd_path).unwrap();
-        let md = MDBook::init(&temp.path())
+        let md = MDBook::init(temp.path())
             .with_config(config)
             .build()
             .unwrap();

tests/cli/init.rs

@@ -0,0 +1,24 @@
+use crate::cli::cmd::mdbook_cmd;
+use crate::dummy_book::DummyBook;
+
+use mdbook::config::Config;
+
+/// Run `mdbook init` with `--force` to skip the confirmation prompts
+#[test]
+fn base_mdbook_init_can_skip_confirmation_prompts() {
+    let temp = DummyBook::new().build().unwrap();
+
+    // doesn't exist before
+    assert!(!temp.path().join("book").exists());
+
+    let mut cmd = mdbook_cmd();
+    cmd.args(["init", "--force"]).current_dir(temp.path());
+    cmd.assert()
+        .success()
+        .stdout(predicates::str::contains("\nAll done, no errors...\n"));
+
+    let config = Config::from_disk(temp.path().join("book.toml")).unwrap();
+    assert_eq!(config.book.title, None);
+
+    assert!(!temp.path().join(".gitignore").exists());
+}

tests/cli/mod.rs

@@ -1,3 +1,4 @@
 mod build;
 mod cmd;
+mod init;
 mod test;

tests/cli/test.rs

@@ -10,11 +10,11 @@ fn mdbook_cli_can_correctly_test_a_passing_book() {
     let mut cmd = mdbook_cmd();
     cmd.arg("test").current_dir(temp.path());
     cmd.assert().success()
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]README.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]intro.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]first[\\/]index.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]first[\\/]nested.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"rustdoc returned an error:\n\n"##).unwrap().not())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "README.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "intro.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "first[\\/]index.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "first[\\/]nested.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"returned an error:\n\n"##).unwrap().not())
       .stderr(predicates::str::is_match(r##"Nested_Chapter::Rustdoc_include_works_with_anchors_too \(line \d+\) ... FAILED"##).unwrap().not());
 }
 
@@ -25,10 +25,10 @@ fn mdbook_cli_detects_book_with_failing_tests() {
     let mut cmd = mdbook_cmd();
     cmd.arg("test").current_dir(temp.path());
     cmd.assert().failure()
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]README.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]intro.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]first[\\/]index.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"Testing file: "([^"]+)[\\/]first[\\/]nested.md""##).unwrap())
-      .stderr(predicates::str::is_match(r##"rustdoc returned an error:\n\n"##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "README.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "intro.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "first[\\/]index.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"Testing chapter [^:]*: "first[\\/]nested.md""##).unwrap())
+      .stderr(predicates::str::is_match(r##"returned an error:\n\n"##).unwrap())
       .stderr(predicates::str::is_match(r##"Nested_Chapter::Rustdoc_include_works_with_anchors_too \(line \d+\) ... FAILED"##).unwrap());
 }

tests/dummy_book/mod.rs

@@ -112,12 +112,12 @@ fn recursive_copy<A: AsRef<Path>, B: AsRef<Path>>(from: A, to: B) -> Result<()>
     let from = from.as_ref();
     let to = to.as_ref();
 
-    for entry in WalkDir::new(&from) {
+    for entry in WalkDir::new(from) {
         let entry = entry.with_context(|| "Unable to inspect directory entry")?;
 
         let original_location = entry.path();
         let relative = original_location
-            .strip_prefix(&from)
+            .strip_prefix(from)
             .expect("`original_location` is inside the `from` directory");
         let new_location = to.join(relative);
 
@@ -126,7 +126,7 @@ fn recursive_copy<A: AsRef<Path>, B: AsRef<Path>>(from: A, to: B) -> Result<()>
                 fs::create_dir_all(parent).with_context(|| "Couldn't create directory")?;
             }
 
-            fs::copy(&original_location, &new_location)
+            fs::copy(original_location, &new_location)
                 .with_context(|| "Unable to copy file contents")?;
         }
     }

tests/dummy_book/src/SUMMARY.md

@@ -14,6 +14,7 @@
     - [Unicode](first/unicode.md)
     - [No Headers](first/no-headers.md)
     - [Duplicate Headers](first/duplicate-headers.md)
+    - [Heading Attributes](first/heading-attributes.md)
 - [Second Chapter](second.md)
     - [Nested Chapter](second/nested.md)
 

tests/dummy_book/src/first/heading-attributes.md

@@ -0,0 +1,5 @@
+# Heading Attributes {#attrs}
+
+## Heading with classes {.class1 .class2}
+
+## Heading with id and classes {#both .class1 .class2}

tests/init.rs

@@ -1,5 +1,6 @@
 use mdbook::config::Config;
 use mdbook::MDBook;
+use pretty_assertions::assert_eq;
 use std::fs;
 use std::fs::File;
 use std::io::prelude::*;
@@ -95,7 +96,7 @@ fn run_mdbook_init_with_custom_book_and_src_locations() {
     let contents = fs::read_to_string(temp.path().join("book.toml")).unwrap();
     assert_eq!(
         contents,
-        "[book]\nauthors = []\nlanguage = \"en\"\nmultilingual = false\nsrc = \"in\"\n\n[build]\nbuild-dir = \"out\"\ncreate-missing = true\nuse-default-preprocessors = true\n"
+        "[book]\nauthors = []\nlanguage = \"en\"\nmultilingual = false\nsrc = \"in\"\n\n[build]\nbuild-dir = \"out\"\ncreate-missing = true\nextra-watch-dirs = []\nuse-default-preprocessors = true\n"
     );
 }
 
@@ -121,6 +122,20 @@ fn copy_theme() {
         "css/variables.css",
         "favicon.png",
         "favicon.svg",
+        "fonts/OPEN-SANS-LICENSE.txt",
+        "fonts/SOURCE-CODE-PRO-LICENSE.txt",
+        "fonts/fonts.css",
+        "fonts/open-sans-v17-all-charsets-300.woff2",
+        "fonts/open-sans-v17-all-charsets-300italic.woff2",
+        "fonts/open-sans-v17-all-charsets-600.woff2",
+        "fonts/open-sans-v17-all-charsets-600italic.woff2",
+        "fonts/open-sans-v17-all-charsets-700.woff2",
+        "fonts/open-sans-v17-all-charsets-700italic.woff2",
+        "fonts/open-sans-v17-all-charsets-800.woff2",
+        "fonts/open-sans-v17-all-charsets-800italic.woff2",
+        "fonts/open-sans-v17-all-charsets-italic.woff2",
+        "fonts/open-sans-v17-all-charsets-regular.woff2",
+        "fonts/source-code-pro-v11-all-charsets-500.woff2",
         "highlight.css",
         "highlight.js",
         "index.hbs",

tests/rendered_output.rs

@@ -1,6 +1,3 @@
-#[macro_use]
-extern crate pretty_assertions;
-
 mod dummy_book;
 
 use crate::dummy_book::{assert_contains_strings, assert_doesnt_contain_strings, DummyBook};
@@ -10,6 +7,7 @@ use mdbook::config::Config;
 use mdbook::errors::*;
 use mdbook::utils::fs::write_file;
 use mdbook::MDBook;
+use pretty_assertions::assert_eq;
 use select::document::Document;
 use select::predicate::{Class, Name, Predicate};
 use std::collections::HashMap;
@@ -37,6 +35,7 @@ const TOC_SECOND_LEVEL: &[&str] = &[
     "1.5. Unicode",
     "1.6. No Headers",
     "1.7. Duplicate Headers",
+    "1.8. Heading Attributes",
     "2.1. Nested Chapter",
 ];
 
@@ -277,7 +276,7 @@ fn root_index_html() -> Result<Document> {
         .with_context(|| "Book building failed")?;
 
     let index_page = temp.path().join("book").join("index.html");
-    let html = fs::read_to_string(&index_page).with_context(|| "Unable to read index.html")?;
+    let html = fs::read_to_string(index_page).with_context(|| "Unable to read index.html")?;
 
     Ok(Document::from(html.as_str()))
 }
@@ -414,7 +413,7 @@ fn recursive_includes_are_capped() {
     let content = &["Around the world, around the world
 Around the world, around the world
 Around the world, around the world"];
-    assert_contains_strings(&recursive, content);
+    assert_contains_strings(recursive, content);
 }
 
 #[test]
@@ -464,7 +463,7 @@ fn by_default_mdbook_use_index_preprocessor_to_convert_readme_to_index() {
 
     let second_index = temp.path().join("book").join("second").join("index.html");
     let unexpected_strings = vec!["Second README"];
-    assert_doesnt_contain_strings(&second_index, &unexpected_strings);
+    assert_doesnt_contain_strings(second_index, &unexpected_strings);
 }
 
 #[test]
@@ -630,10 +629,8 @@ fn edit_url_has_configured_src_dir_edit_url() {
 }
 
 fn remove_absolute_components(path: &Path) -> impl Iterator<Item = Component> + '_ {
-    path.components().skip_while(|c| match c {
-        Component::Prefix(_) | Component::RootDir => true,
-        _ => false,
-    })
+    path.components()
+        .skip_while(|c| matches!(c, Component::Prefix(_) | Component::RootDir))
 }
 
 /// Checks formatting of summary names with inline elements.
@@ -758,6 +755,7 @@ mod search {
         let no_headers = get_doc_ref("first/no-headers.html");
         let duplicate_headers_1 = get_doc_ref("first/duplicate-headers.html#header-text-1");
         let conclusion = get_doc_ref("conclusion.html#conclusion");
+        let heading_attrs = get_doc_ref("first/heading-attributes.html#both");
 
         let bodyidx = &index["index"]["index"]["body"]["root"];
         let textidx = &bodyidx["t"]["e"]["x"]["t"];
@@ -770,7 +768,7 @@ mod search {
         assert_eq!(docs[&some_section]["body"], "");
         assert_eq!(
             docs[&summary]["body"],
-            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Second Chapter Nested Chapter Conclusion"
+            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Heading Attributes Second Chapter Nested Chapter Conclusion"
         );
         assert_eq!(
             docs[&summary]["breadcrumbs"],
@@ -789,6 +787,10 @@ mod search {
             docs[&no_headers]["body"],
             "Capybara capybara capybara. Capybara capybara capybara. ThisLongWordIsIncludedSoWeCanCheckThatSufficientlyLongWordsAreOmittedFromTheSearchIndex."
         );
+        assert_eq!(
+            docs[&heading_attrs]["breadcrumbs"],
+            "First Chapter » Heading Attributes » Heading with id and classes"
+        );
     }
 
     // Setting this to `true` may cause issues with `cargo watch`,
@@ -805,7 +807,7 @@ mod search {
             let src = read_book_index(temp.path());
 
             let dest = Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/searchindex_fixture.json");
-            let dest = File::create(&dest).unwrap();
+            let dest = File::create(dest).unwrap();
             serde_json::to_writer_pretty(dest, &src).unwrap();
 
             src
@@ -842,3 +844,127 @@ mod search {
         }
     }
 }
+
+#[test]
+fn custom_fonts() {
+    // Tests to ensure custom fonts are copied as expected.
+    let builtin_fonts = [
+        "OPEN-SANS-LICENSE.txt",
+        "SOURCE-CODE-PRO-LICENSE.txt",
+        "fonts.css",
+        "open-sans-v17-all-charsets-300.woff2",
+        "open-sans-v17-all-charsets-300italic.woff2",
+        "open-sans-v17-all-charsets-600.woff2",
+        "open-sans-v17-all-charsets-600italic.woff2",
+        "open-sans-v17-all-charsets-700.woff2",
+        "open-sans-v17-all-charsets-700italic.woff2",
+        "open-sans-v17-all-charsets-800.woff2",
+        "open-sans-v17-all-charsets-800italic.woff2",
+        "open-sans-v17-all-charsets-italic.woff2",
+        "open-sans-v17-all-charsets-regular.woff2",
+        "source-code-pro-v11-all-charsets-500.woff2",
+    ];
+    let actual_files = |path: &Path| -> Vec<String> {
+        let mut actual: Vec<_> = path
+            .read_dir()
+            .unwrap()
+            .map(|entry| entry.unwrap().file_name().into_string().unwrap())
+            .collect();
+        actual.sort();
+        actual
+    };
+    let has_fonts_css = |path: &Path| -> bool {
+        let contents = fs::read_to_string(path.join("book/index.html")).unwrap();
+        contents.contains("fonts/fonts.css")
+    };
+
+    // No theme:
+    let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
+    let p = temp.path();
+    MDBook::init(p).build().unwrap();
+    MDBook::load(p).unwrap().build().unwrap();
+    assert_eq!(actual_files(&p.join("book/fonts")), &builtin_fonts);
+    assert!(has_fonts_css(p));
+
+    // Full theme.
+    let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
+    let p = temp.path();
+    MDBook::init(p).copy_theme(true).build().unwrap();
+    assert_eq!(actual_files(&p.join("theme/fonts")), &builtin_fonts);
+    MDBook::load(p).unwrap().build().unwrap();
+    assert_eq!(actual_files(&p.join("book/fonts")), &builtin_fonts);
+    assert!(has_fonts_css(p));
+
+    // Mixed with copy-fonts=true
+    // Should ignore the copy-fonts setting since the user has provided their own fonts.css.
+    let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
+    let p = temp.path();
+    MDBook::init(p).build().unwrap();
+    write_file(&p.join("theme/fonts"), "fonts.css", b"/*custom*/").unwrap();
+    write_file(&p.join("theme/fonts"), "myfont.woff", b"").unwrap();
+    MDBook::load(p).unwrap().build().unwrap();
+    assert!(has_fonts_css(p));
+    assert_eq!(
+        actual_files(&p.join("book/fonts")),
+        ["fonts.css", "myfont.woff"]
+    );
+
+    // copy-fonts=false, no theme
+    // This should generate a deprecation warning.
+    let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
+    let p = temp.path();
+    MDBook::init(p).build().unwrap();
+    let config = Config::from_str("output.html.copy-fonts = false").unwrap();
+    MDBook::load_with_config(p, config)
+        .unwrap()
+        .build()
+        .unwrap();
+    assert!(!has_fonts_css(p));
+    assert!(!p.join("book/fonts").exists());
+
+    // copy-fonts=false with empty fonts.css
+    let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
+    let p = temp.path();
+    MDBook::init(p).build().unwrap();
+    write_file(&p.join("theme/fonts"), "fonts.css", b"").unwrap();
+    let config = Config::from_str("output.html.copy-fonts = false").unwrap();
+    MDBook::load_with_config(p, config)
+        .unwrap()
+        .build()
+        .unwrap();
+    assert!(!has_fonts_css(p));
+    assert!(!p.join("book/fonts").exists());
+
+    // copy-fonts=false with fonts theme
+    let temp = TempFileBuilder::new().prefix("mdbook").tempdir().unwrap();
+    let p = temp.path();
+    MDBook::init(p).build().unwrap();
+    write_file(&p.join("theme/fonts"), "fonts.css", b"/*custom*/").unwrap();
+    write_file(&p.join("theme/fonts"), "myfont.woff", b"").unwrap();
+    let config = Config::from_str("output.html.copy-fonts = false").unwrap();
+    MDBook::load_with_config(p, config)
+        .unwrap()
+        .build()
+        .unwrap();
+    assert!(has_fonts_css(p));
+    assert_eq!(
+        actual_files(&p.join("book/fonts")),
+        &["fonts.css", "myfont.woff"]
+    );
+}
+
+#[test]
+fn custom_header_attributes() {
+    let temp = DummyBook::new().build().unwrap();
+    let md = MDBook::load(temp.path()).unwrap();
+    md.build().unwrap();
+
+    let contents = temp.path().join("book/first/heading-attributes.html");
+
+    let summary_strings = &[
+        r##"<h1 id="attrs"><a class="header" href="#attrs">Heading Attributes</a></h1>"##,
+        r##"<h2 id="heading-with-classes" class="class1 class2"><a class="header" href="#heading-with-classes">Heading with classes</a></h2>"##,
+        r##"<h2 id="both" class="class1 class2"><a class="header" href="#both">Heading with id and classes</a></h2>"##,
+    ];
+    assert_contains_strings(&contents, summary_strings);
+}

tests/testing.rs

@@ -24,3 +24,24 @@ fn mdbook_detects_book_with_failing_tests() {
 
     assert!(md.test(vec![]).is_err());
 }
+
+#[test]
+fn mdbook_test_chapter() {
+    let temp = DummyBook::new().with_passing_test(true).build().unwrap();
+    let mut md = MDBook::load(temp.path()).unwrap();
+
+    let result = md.test_chapter(vec![], Some("Introduction"));
+    assert!(
+        result.is_ok(),
+        "test_chapter failed with {}",
+        result.err().unwrap()
+    );
+}
+
+#[test]
+fn mdbook_test_chapter_not_found() {
+    let temp = DummyBook::new().with_passing_test(true).build().unwrap();
+    let mut md = MDBook::load(temp.path()).unwrap();
+
+    assert!(md.test_chapter(vec![], Some("Bogus Chapter Name")).is_err());
+}

triagebot.toml

@@ -1,12 +1,23 @@
 # This will allow users to self assign, and/or drop assignment
 [assign]
 
+# Allows @rustbot ready, review, author, or blocked
+[shortcut]
 
 [relabel]
 allow-unauthenticated = [
-# For Issue areas
+    # For Issue areas
     "A-*",
-    "E-Help-Wanted",
-    "Bug",
-    "Feature-Request"
-]
+    # Categories
+    "C-*",
+    # Commands
+    "Command-*",
+    # Status
+    "S-*",
+    "regression",
+    "Breaking Change",
+    "msrv-bump",
+]
+
+[autolabel."S-waiting-on-review"]
+new_pr = true