Files
compiler-explorer/webpack.config.esm.ts
Matt Godbolt 3a211aaf0f Remove the manual webpackJsHack static-asset version (#8848)
> [!IMPORTANT]
> **Draft / do not merge yet.** Depends on
[infra#2188](https://github.com/compiler-explorer/infra/pull/2188) being
merged **and deployed** first. Until then, this `webpackJsHack` constant
is still the only escape hatch for the source-map hash collisions, so it
must stay. There's no deadline on this PR — it's pure cleanup that can
wait indefinitely.

## What

Removes the `webpackJsHack` `.vNN.` infix from the static asset
filenames (`[name].vNN.[contenthash].js` → `[name].[contenthash].js`,
and likewise for `.css` and worker files), along with its now-misleading
"Hack alert" comment.

## Why

This constant was a **manual escape hatch**. The CDN serves static files
with a one-year immutable cache and verifies (in CI, `ce ... builds
check_hashes`) that a given filename never changes content. Source maps
are named after their *asset's* content hash (`<asset>.map`), so a
toolchain bump that regenerated a map for byte-identical JS/CSS reused
the same `.map` filename with different bytes → the check failed, and we
manually bumped this constant to rename every asset and dodge the
collision.

[infra#2188](https://github.com/compiler-explorer/infra/pull/2188) fixes
the root cause: source maps are debug-only metadata, not code, so
they're now exempt from the immutable-hash check, overwritten on deploy,
and served `no-cache` (so debugging always gets the current map). With
that deployed, this constant can never need bumping again.

## The comment was true once — on webpack 4 — but has been obsolete
since the webpack 5 upgrade

The "Hack alert" comment claims the bumps are needed for *"webpack
changes that affect how minification is done, even though that's
supposed not to matter."* That was accurate when it was written, but
stopped being true years ago:

| When | webpack | What | Minification claim valid? |
|------|---------|------|---------------------------|
| 2020-04-18 (`67575197f`, *"Add a hacky fix for the cannot upload over
identical file"*) | **4.42.1** | Comment + manual version introduced;
template changed `[chunkhash]` → `v2.[contenthash]` | **Yes** |
| 2021-12-21 (`7c20613c5`, *"Move to using webpack5 (#3197)"*) |
**5.65.0** | Upgrade to webpack 5 | **No — obsolete from here on** |

- **On webpack 4** there was no `realContentHash`; JS hashes were
computed from the chunk's module content *before* Terser ran. So a
webpack/minifier change that altered the *minified* output left the hash
unchanged → same filename, different bytes → "cannot upload over
identical file". The manual version was a genuine fix, and the comment
correctly described pre-minification hashing.
- **Since webpack 5** (`realContentHash: true`, default-on in
production, landed in 5.8) every `[contenthash]` is recomputed from the
**final, post-minification** bytes. A minifier change now produces a
*new filename* on its own — it can no longer collide. So the
minification rationale has been dead for ~3.5 years.

That means essentially every version bump from the webpack-5 era onward
(the `v2 → … → v69` march) was a **source-map** collision misattributed
to minification — the source map being the one asset whose name still
isn't a hash of its own post-processed content. That is exactly what
infra#2188 addresses.

### Net

- A real code change or a minifier change → different post-minification
bytes → different `[contenthash]` → new filename. Handled correctly by
content-addressing; no hack needed.
- The only same-name-different-bytes case was source maps → fixed by
infra#2188.
- So removing `webpackJsHack` (and its misleading comment) is safe once
infra#2188 is deployed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: mattgodbolt-molty <mattgodbolt-molty@users.noreply.github.com>
2026-07-02 14:08:23 -05:00

212 lines
6.9 KiB
TypeScript

// Copyright (c) 2020, Compiler Explorer Authors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import {fileURLToPath} from 'node:url';
import CopyWebpackPlugin from 'copy-webpack-plugin';
import CssMinimizerPlugin from 'css-minimizer-webpack-plugin';
import MiniCssExtractPlugin from 'mini-css-extract-plugin';
import MonacoEditorWebpackPlugin from 'monaco-editor-webpack-plugin';
import TerserPlugin from 'terser-webpack-plugin';
import Webpack from 'webpack';
import {WebpackManifestPlugin} from 'webpack-manifest-plugin';
const __dirname = path.resolve(path.dirname(fileURLToPath(import.meta.url)));
const isDev = process.env.NODE_ENV !== 'production';
function log(message: string) {
console.log('webpack: ', message);
}
log(`compiling for ${isDev ? 'development' : 'production'}.`);
// Memory limits us in most cases, so restrict parallelism to keep us in a sane amount of RAM
const parallelism = Math.floor(os.totalmem() / (4 * 1024 * 1024 * 1024)) + 1;
log(`Limiting parallelism to ${parallelism}`);
const manifestPath = path.resolve(__dirname, 'out', 'dist');
const staticPath = path.resolve(__dirname, 'out', 'webpack', 'static');
const hasGit = fs.existsSync(path.resolve(__dirname, '.git'));
const plugins: Webpack.WebpackPluginInstance[] = [
new MonacoEditorWebpackPlugin({
languages: [
'cpp',
'go',
'pascal',
'perl',
'python',
'rust',
'swift',
'java',
'julia',
'kotlin',
'scala',
'ruby',
'csharp',
'fsharp',
'vb',
'dart',
'typescript',
'solidity',
'scheme',
'objective-c',
'elixir',
'clojure',
],
filename: isDev ? '[name].worker.js' : '[name].worker.[contenthash].js',
}),
new MiniCssExtractPlugin({
filename: isDev ? '[name].css' : '[name].[contenthash].css',
}),
new WebpackManifestPlugin({
fileName: path.resolve(manifestPath, 'manifest.json'),
publicPath: '',
}),
new Webpack.DefinePlugin({
'window.PRODUCTION': JSON.stringify(!isDev),
}),
new CopyWebpackPlugin({
patterns: [{from: './public', to: staticPath}],
}),
];
if (isDev) {
plugins.push(new Webpack.HotModuleReplacementPlugin());
}
export default {
mode: isDev ? 'development' : 'production',
entry: {
main: './static/main.ts',
noscript: './static/noscript.ts',
},
output: {
filename: isDev ? '[name].js' : '[name].[contenthash].js',
path: staticPath,
},
cache: {
type: 'filesystem',
buildDependencies: {
config: [
fileURLToPath(import.meta.url),
// Depend on the package.json to force a recache if something changes:
// this is only because something in Monaco upsets the cache if its version changes
path.resolve(__dirname, 'package.json'),
],
},
},
resolve: {
alias: {
'monaco-editor$': 'monaco-editor/esm/vs/editor/editor.api',
},
fallback: {
path: 'path-browserify',
},
modules: ['./static', './node_modules'],
extensions: ['.ts', '.js'],
extensionAlias: {
'.js': ['.ts', '.js'],
'.mjs': ['.mts', '.mjs'],
},
},
stats: 'normal',
devtool: 'source-map',
optimization: {
runtimeChunk: 'single',
splitChunks: {
cacheGroups: {
vendors: {
test: /[/\\]node_modules[/\\]/,
name: 'vendor',
chunks: 'all',
priority: -10,
},
},
},
moduleIds: 'deterministic',
minimizer: [
new CssMinimizerPlugin(),
new TerserPlugin({
parallel: true,
terserOptions: {
ecma: 5,
sourceMap: true,
},
}),
],
},
parallelism: parallelism,
module: {
rules: [
{
test: /\.s?css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
publicPath: './',
},
},
'css-loader',
{
loader: 'sass-loader',
options: {
sassOptions: {
fatalDeprecations: ['import'],
},
},
},
{
loader: path.resolve(__dirname, 'etc/webpack/replace-golden-layout-imports.js'),
},
],
},
{
test: /\.(png|woff|woff2|eot|ttf|svg)$/,
type: 'asset',
parser: {dataUrlCondition: {maxSize: 8192}},
},
{
test: /\.pug$/,
loader: path.resolve(__dirname, 'etc/webpack/parsed-pug-loader.js'),
options: {
useGit: hasGit,
},
},
{
test: /\.ts$/,
loader: 'ts-loader',
},
{
test: /\.js$/,
loader: 'source-map-loader',
},
],
},
plugins: plugins,
} satisfies Webpack.Configuration;