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Run Closure on non-minified prod builds, too #28827

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merged 1 commit into from
Apr 19, 2024
Merged

Run Closure on non-minified prod builds, too #28827

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1 change: 1 addition & 0 deletions package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,7 @@
"shelljs": "^0.8.5",
"signedsource": "^2.0.0",
"targz": "^1.0.1",
"terser": "^5.30.3",
"through2": "^3.0.1",
"tmp": "^0.1.0",
"typescript": "^3.7.5",
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253 changes: 129 additions & 124 deletions scripts/rollup/build.js
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Expand Up @@ -23,6 +23,7 @@ const Packaging = require('./packaging');
const {asyncRimRaf} = require('./utils');
const codeFrame = require('@babel/code-frame');
const Wrappers = require('./wrappers');
const minify = require('terser').minify;

const RELEASE_CHANNEL = process.env.RELEASE_CHANNEL;

Expand Down Expand Up @@ -455,137 +456,58 @@ function getPlugins(
);
},
},
// License and haste headers for artifacts with sourcemaps
// For artifacts with sourcemaps we apply these headers
// before passing sources to the Closure compiler, which will be building sourcemaps
needsSourcemaps && {
name: 'license-and-signature-header-for-artifacts-with-sourcemaps',
renderChunk(source) {
return Wrappers.wrapWithLicenseHeader(
source,
bundleType,
globalName,
filename,
moduleType
);
},
},
// Apply dead code elimination and/or minification.
// closure doesn't yet support leaving ESM imports intact
// For production builds, compile with Closure. We do this even for the
// "non-minified" production builds because Closure is much better at
// minification than what most applications use. During this step, we do
// preserve the original symbol names, though, so the resulting code is
// relatively readable.
//
// For the minified builds, the names will be mangled later.
//
// We don't bother with sourcemaps at this step. The sourcemaps we publish
// are only for whitespace and symbol renaming; they don't map back to
// before Closure was applied.
needsMinifiedByClosure &&
closure(
{
compilation_level: 'SIMPLE',
language_in: 'ECMASCRIPT_2020',
language_out:
bundleType === NODE_ES2015
? 'ECMASCRIPT_2020'
: bundleType === BROWSER_SCRIPT
? 'ECMASCRIPT5'
: 'ECMASCRIPT5_STRICT',
emit_use_strict:
bundleType !== BROWSER_SCRIPT &&
bundleType !== ESM_PROD &&
bundleType !== ESM_DEV,
env: 'CUSTOM',
warning_level: 'QUIET',
source_map_include_content: true,
use_types_for_optimization: false,
process_common_js_modules: false,
rewrite_polyfills: false,
inject_libraries: false,
allow_dynamic_import: true,

// Don't let it create global variables in the browser.
// https://github.com/facebook/react/issues/10909
assume_function_wrapper: true,
renaming: !shouldStayReadable,
},
{needsSourcemaps}
),
// Add the whitespace back if necessary.
shouldStayReadable &&
closure({
compilation_level: 'SIMPLE',
language_in: 'ECMASCRIPT_2020',
language_out:
bundleType === NODE_ES2015
? 'ECMASCRIPT_2020'
: bundleType === BROWSER_SCRIPT
? 'ECMASCRIPT5'
: 'ECMASCRIPT5_STRICT',
emit_use_strict:
bundleType !== BROWSER_SCRIPT &&
bundleType !== ESM_PROD &&
bundleType !== ESM_DEV,
env: 'CUSTOM',
warning_level: 'QUIET',
source_map_include_content: true,
use_types_for_optimization: false,
process_common_js_modules: false,
rewrite_polyfills: false,
inject_libraries: false,
allow_dynamic_import: true,

// Don't let it create global variables in the browser.
// https://github.com/facebook/react/issues/10909
assume_function_wrapper: true,

// Don't rename symbols (variable names, functions, etc). This will
// be handled in a later step.
renaming: false,
}),
needsMinifiedByClosure &&
// Add the whitespace back
prettier({
parser: 'flow',
singleQuote: false,
trailingComma: 'none',
bracketSpacing: true,
}),
needsSourcemaps && {
name: 'generate-prod-bundle-sourcemaps',
async renderChunk(minifiedCodeWithChangedHeader, chunk, options, meta) {
// We want to generate a sourcemap that shows the production bundle source
// as it existed before Closure Compiler minified that chunk, rather than
// showing the "original" individual source files. This better shows
// what is actually running in the app.

// Use a path like `node_modules/react/cjs/react.production.min.js.map` for the sourcemap file
const finalSourcemapPath = options.file.replace('.js', '.js.map');
const finalSourcemapFilename = path.basename(finalSourcemapPath);
const outputFolder = path.dirname(options.file);

// Read the sourcemap that Closure wrote to disk
const sourcemapAfterClosure = JSON.parse(
fs.readFileSync(finalSourcemapPath, 'utf8')
);

// Represent the "original" bundle as a file with no `.min` in the name
const filenameWithoutMin = filename.replace('.min', '');
// There's _one_ artifact where the incoming filename actually contains
// a folder name: "use-sync-external-store-shim/with-selector.production.js".
// The output path already has the right structure, but we need to strip this
// down to _just_ the JS filename.
const preMinifiedFilename = path.basename(filenameWithoutMin);

// CC generated a file list that only contains the tempfile name.
// Replace that with a more meaningful "source" name for this bundle
// that represents "the bundled source before minification".
sourcemapAfterClosure.sources = [preMinifiedFilename];
sourcemapAfterClosure.file = filename;

// All our code is considered "third-party" and should be ignored by default.
sourcemapAfterClosure.ignoreList = [0];

// We'll write the pre-minified source to disk as a separate file.
// Because it sits on disk, there's no need to have it in the `sourcesContent` array.
// That also makes the file easier to read, and available for use by scripts.
// This should be the only file in the array.
const [preMinifiedBundleSource] =
sourcemapAfterClosure.sourcesContent;

// Remove this entirely - we're going to write the file to disk instead.
delete sourcemapAfterClosure.sourcesContent;

const preMinifiedBundlePath = path.join(
outputFolder,
preMinifiedFilename
);

// Write the original source to disk as a separate file
fs.writeFileSync(preMinifiedBundlePath, preMinifiedBundleSource);

// Overwrite the Closure-generated file with the final combined sourcemap
fs.writeFileSync(
finalSourcemapPath,
JSON.stringify(sourcemapAfterClosure)
);

// Add the sourcemap URL to the actual bundle, so that tools pick it up
const sourceWithMappingUrl =
minifiedCodeWithChangedHeader +
`\n//# sourceMappingURL=${finalSourcemapFilename}`;

return {
code: sourceWithMappingUrl,
map: null,
};
},
},
// License and haste headers for artifacts without sourcemaps
// Primarily used for FB-artifacts, which should preserve specific format of the header
// Which potentially can be changed by Closure minification
!needsSourcemaps && {
name: 'license-and-signature-header-for-artifacts-without-sourcemaps',
{
name: 'license-and-signature-header',
renderChunk(source) {
return Wrappers.wrapWithLicenseHeader(
source,
Expand All @@ -596,6 +518,89 @@ function getPlugins(
);
},
},
isProduction &&
!shouldStayReadable && {
name: 'mangle-symbol-names',
async renderChunk(code, chunk, options, meta) {
// Minify the code by mangling symbol names. We already ran Closure
// on this code, so stuff like dead code elimination and inlining
// has already happened. This step is purely to rename the symbols,
// which we asked Closure to preserve.
//
// The only reason this is a separate step from Closure is so we
// can publish non-mangled versions of the code for easier debugging
// in production. We also publish sourcemaps that map back to the
// non-mangled code (*not* the pre-Closure code).

const outputFolder = path.dirname(options.file);

// Represent the "original" bundle as a file with no `.min` in the name
const filenameWithoutMin = filename.replace('.min', '');
// There's _one_ artifact where the incoming filename actually contains
// a folder name: "use-sync-external-store-shim/with-selector.production.js".
// The output path already has the right structure, but we need to strip this
// down to _just_ the JS filename.
const preMinifiedFilename = path.basename(filenameWithoutMin);
const preMinifiedBundlePath = path.join(
outputFolder,
preMinifiedFilename
);

// Use a path like `node_modules/react/cjs/react.production.min.js.map` for the sourcemap file
const finalSourcemapPath = options.file.replace('.js', '.js.map');
const finalSourcemapFilename = path.basename(finalSourcemapPath);

const terserOptions = {
// Don't bother compressing. Closure already did that.
compress: false,
toplevel: true,
// Mangle the symbol names.
mangle: {
toplevel: true,
},
};
if (needsSourcemaps) {
terserOptions.sourceMap = {
// Used to set the `file` field in the sourcemap
filename: filename,
// Used to set `# sourceMappingURL=` in the compiled code
url: finalSourcemapFilename,
};
}

const minifiedResult = await minify(
{[preMinifiedFilename]: code},
terserOptions
);

// Create the directory if it doesn't already exist
fs.mkdirSync(outputFolder, {recursive: true});

if (needsSourcemaps) {
const sourcemapJSON = JSON.parse(minifiedResult.map);

// All our code is considered "third-party" and should be ignored
// by default
sourcemapJSON.ignoreList = [0];

// Write the sourcemap to disk
fs.writeFileSync(
finalSourcemapPath,
JSON.stringify(sourcemapJSON)
);
}

// Write the original source to disk as a separate file
fs.writeFileSync(preMinifiedBundlePath, code);

return {
code: minifiedResult.code,
// TODO: Maybe we should use Rollup's sourcemap feature instead
// of writing it to disk manually?
map: null,
};
},
},
// Record bundle size.
sizes({
getSize: (size, gzip) => {
Expand Down
6 changes: 1 addition & 5 deletions scripts/rollup/plugins/closure-plugin.js
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Expand Up @@ -19,20 +19,16 @@ function compile(flags) {
});
}

module.exports = function closure(flags = {}, {needsSourcemaps}) {
module.exports = function closure(flags = {}) {
return {
name: 'scripts/rollup/plugins/closure-plugin',
async renderChunk(code, chunk, options) {
const inputFile = tmp.fileSync();

// Use a path like `node_modules/react/cjs/react.production.min.js.map` for the sourcemap file
const sourcemapPath = options.file.replace('.js', '.js.map');

// Tell Closure what JS source file to read, and optionally what sourcemap file to write
const finalFlags = {
...flags,
js: inputFile.name,
...(needsSourcemaps && {create_source_map: sourcemapPath}),
};

await writeFileAsync(inputFile.name, code, 'utf8');
Expand Down
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