webpack/lib/SourceMapDevToolPlugin.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

const asyncLib = require("neo-async");
const { ConcatSource, RawSource } = require("webpack-sources");
const Compilation = require("./Compilation");
const ModuleFilenameHelpers = require("./ModuleFilenameHelpers");
const ProgressPlugin = require("./ProgressPlugin");
const SourceMapDevToolModuleOptionsPlugin = require("./SourceMapDevToolModuleOptionsPlugin");
const createHash = require("./util/createHash");
const { dirname, relative } = require("./util/fs");
const generateDebugId = require("./util/generateDebugId");
const { makePathsAbsolute } = require("./util/identifier");

/** @typedef {import("webpack-sources").MapOptions} MapOptions */
/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../declarations/WebpackOptions").DevtoolNamespace} DevtoolNamespace */
/** @typedef {import("../declarations/WebpackOptions").DevtoolModuleFilenameTemplate} DevtoolModuleFilenameTemplate */
/** @typedef {import("../declarations/WebpackOptions").DevtoolFallbackModuleFilenameTemplate} DevtoolFallbackModuleFilenameTemplate */
/** @typedef {import("../declarations/plugins/SourceMapDevToolPlugin").SourceMapDevToolPluginOptions} SourceMapDevToolPluginOptions */
/** @typedef {import("../declarations/plugins/SourceMapDevToolPlugin").Rules} Rules */
/** @typedef {import("./CacheFacade").ItemCacheFacade} ItemCacheFacade */
/** @typedef {import("./Chunk")} Chunk */
/** @typedef {import("./Compilation").Asset} Asset */
/** @typedef {import("./Compilation").AssetInfo} AssetInfo */
/** @typedef {import("./Compiler")} Compiler */
/** @typedef {import("./Module")} Module */
/** @typedef {import("./NormalModule").RawSourceMap} RawSourceMap */
/** @typedef {import("./TemplatedPathPlugin").TemplatePath} SourceMappingURLComment */
/** @typedef {import("./util/fs").OutputFileSystem} OutputFileSystem */

/**
 * Defines the source map task type used by this module.
 * @typedef {object} SourceMapTask
 * @property {AssetInfo} assetInfo
 * @property {(string | Module)[]} modules
 * @property {string} source
 * @property {string} file
 * @property {RawSourceMap} sourceMap
 * @property {Source} mapSource the Source instance whose `sourceAndMap` we called (the current asset or, when its map was already stripped, the pinned original from `originalSources`) — what `clearCache` should target
 * @property {ItemCacheFacade} cacheItem cache item
 */

const METACHARACTERS_REGEXP = /[-[\]\\/{}()*+?.^$|]/g;
const CONTENT_HASH_DETECT_REGEXP = /\[contenthash(?::\w+)?\]/;
const CSS_AND_JS_MODULE_EXTENSIONS_REGEXP = /\.((c|m)?js|css)($|\?)/i;
const CSS_EXTENSION_DETECT_REGEXP = /\.css(?:$|\?)/i;
const MAP_URL_COMMENT_REGEXP = /\[map\]/g;
const URL_COMMENT_REGEXP = /\[url\]/g;
const URL_FORMATTING_REGEXP = /^\n\/\/(.*)$/;

/**
 * Reset's .lastIndex of stateful Regular Expressions
 * For when `test` or `exec` is called on them
 * @param {RegExp} regexp Stateful Regular Expression to be reset
 * @returns {void}
 */
const resetRegexpState = (regexp) => {
	regexp.lastIndex = -1;
};

/**
 * Escapes regular expression metacharacters
 * @param {string} str String to quote
 * @returns {string} Escaped string
 */
const quoteMeta = (str) => str.replace(METACHARACTERS_REGEXP, "\\$&");

/**
 * Compilation-scoped registry of original asset sources for multi-plugin
 * cooperation. The first SourceMapDevToolPlugin instance to see a file pins a
 * reference to the asset's still-unwrapped {@link Source} object; later
 * instances whose `asset.source.sourceAndMap()` would now return `null` (the
 * earlier instance replaced the asset with a `RawSource`) can re-extract the
 * map from this pinned reference. We keep the registry on a module-scoped
 * `WeakMap` so the entries are reclaimed automatically when the compilation
 * itself becomes unreachable; we never store anything on the compilation
 * object directly.
 *
 * Stashing the `Source` object itself rather than an extracted map keeps the
 * fast path free of cloning and source-map serialization work — the
 * extraction only happens if a subsequent plugin actually needs the map.
 * @type {WeakMap<Compilation, Map<string, Source>>}
 */
const originalSourceRegistry = new WeakMap();

/**
 * Returns (creating if necessary) the per-compilation registry of original
 * asset {@link Source} objects.
 * @param {Compilation} compilation compilation
 * @returns {Map<string, Source>} registry
 */
const getOriginalSourceRegistry = (compilation) => {
	let registry = originalSourceRegistry.get(compilation);
	if (registry === undefined) {
		registry = new Map();
		originalSourceRegistry.set(compilation, registry);
	}
	return registry;
};

/**
 * Extracts source and source map from a Source object, falling back to a
 * registered original source for assets that another SourceMapDevToolPlugin
 * instance has already wrapped (whose internal map is now `null`).
 *
 * The returned source is read from the asset as it currently stands — that way
 * any `sourceMappingURL` comments appended by earlier plugin instances survive
 * — while the map is taken from the pinned original Source when the current
 * one no longer carries it. `mapSource` identifies which Source instance was
 * actually queried for the map (the current asset, or the pinned original);
 * that's the one whose internal caches the caller should release.
 * @param {string} file file name
 * @param {Source} asset source object as currently held by the compilation
 * @param {MapOptions} options map extraction options
 * @param {Map<string, Source>} registry compilation-scoped original-source registry
 * @returns {{ source: string, sourceMap: RawSourceMap, mapSource: Source } | undefined} extracted pair or `undefined` when no map is recoverable
 */
const extractSourceAndMap = (file, asset, options, registry) => {
	/** @type {string | Buffer} */
	let source;
	/** @type {null | RawSourceMap} */
	let sourceMap;
	if (asset.sourceAndMap) {
		const sourceAndMap = asset.sourceAndMap(options);
		source = sourceAndMap.source;
		sourceMap = sourceAndMap.map;
	} else {
		source = asset.source();
		sourceMap = asset.map(options);
	}
	// Bail before touching the registry if we can't return a usable string
	// source — pinning a non-string-producing asset would only waste the slot.
	if (typeof source !== "string") return;
	if (sourceMap) {
		// The current asset still owns the original map — pin a reference so
		// that a later plugin instance (which will see a rewrapped asset
		// without a map) can recover it on demand.
		if (!registry.has(file)) registry.set(file, asset);
		return { source, sourceMap, mapSource: asset };
	}
	// The current asset (typically a `RawSource` left by an earlier
	// SourceMapDevToolPlugin instance) has no internal map. Re-extract
	// the map from the original Source we pinned earlier. We keep using
	// `source` from the current asset so that any prior wrappers (e.g.
	// appended sourceMappingURL comments) are preserved.
	const original = registry.get(file);
	if (!original) return;
	sourceMap = original.sourceAndMap
		? original.sourceAndMap(options).map
		: original.map(options);
	if (!sourceMap) return;
	return { source, sourceMap, mapSource: original };
};

/**
 * Creating {@link SourceMapTask} for given file
 * @param {string} file current compiled file
 * @param {Source} asset the asset
 * @param {AssetInfo} assetInfo the asset info
 * @param {MapOptions} options source map options
 * @param {Compilation} compilation compilation instance
 * @param {ItemCacheFacade} cacheItem cache item
 * @param {Map<string, Source>} registry compilation-scoped original-source registry
 * @returns {SourceMapTask | undefined} created task instance or `undefined`
 */
const getTaskForFile = (
	file,
	asset,
	assetInfo,
	options,
	compilation,
	cacheItem,
	registry
) => {
	const extracted = extractSourceAndMap(file, asset, options, registry);
	if (!extracted) return;
	const { source, sourceMap, mapSource } = extracted;
	const context = compilation.options.context;
	const root = compilation.compiler.root;
	const cachedAbsolutify = makePathsAbsolute.bindContextCache(context, root);
	const modules = sourceMap.sources.map((source) => {
		if (!source.startsWith("webpack://")) return source;
		source = cachedAbsolutify(source.slice(10));
		const module = compilation.findModule(source);
		return module || source;
	});

	return {
		file,
		source: /** @type {string} */ (source),
		assetInfo,
		sourceMap,
		mapSource,
		modules,
		cacheItem
	};
};

const PLUGIN_NAME = "SourceMapDevToolPlugin";

/**
 * Maps a configuration value (string, RegExp, function, nullish, or array of
 * such) into a JSON-serializable form. Functions and RegExps are turned into
 * their `.toString()` representation so that changes to inline callbacks
 * invalidate caches; everything else is returned as-is so that the surrounding
 * `JSON.stringify` does the escaping.
 *
 * The result is used through `JSON.stringify` to build cache identifiers, so
 * we deliberately avoid any homemade `|` / `,` separators that could collide
 * with characters appearing inside user-provided values such as `publicPath`,
 * template strings, or `sourceRoot`.
 * @param {EXPECTED_ANY} value option value
 * @returns {EXPECTED_ANY} JSON-serializable representation
 */
const toCacheKeyValue = (value) => {
	if (value === undefined || value === null) return value;
	if (Array.isArray(value)) return value.map(toCacheKeyValue);
	if (value instanceof RegExp || typeof value === "function") {
		return value.toString();
	}
	return value;
};

class SourceMapDevToolPlugin {
	/**
	 * Creates an instance of SourceMapDevToolPlugin.
	 * @param {SourceMapDevToolPluginOptions=} options options object
	 * @throws {Error} throws error, if got more than 1 arguments
	 */
	constructor(options = {}) {
		/** @type {undefined | null | false | string} */
		this.sourceMapFilename = options.filename;
		/** @type {false | SourceMappingURLComment} */
		this.sourceMappingURLComment =
			options.append === false
				? false
				: // eslint-disable-next-line no-useless-concat
					options.append || "\n//# source" + "MappingURL=[url]";
		/** @type {DevtoolModuleFilenameTemplate} */
		this.moduleFilenameTemplate =
			options.moduleFilenameTemplate || "webpack://[namespace]/[resourcePath]";
		/** @type {DevtoolFallbackModuleFilenameTemplate} */
		this.fallbackModuleFilenameTemplate =
			options.fallbackModuleFilenameTemplate ||
			"webpack://[namespace]/[resourcePath]?[hash]";
		/** @type {DevtoolNamespace} */
		this.namespace = options.namespace || "";
		/** @type {SourceMapDevToolPluginOptions} */
		this.options = options;
		// Cache salt derived from output-affecting options, so that two
		// SourceMapDevToolPlugin instances (or `devtool` + a plugin) operating
		// on the same asset don't share a cache entry. We serialize via
		// `JSON.stringify` rather than a homemade separator so that any
		// special characters (e.g. `|` inside a publicPath or sourceRoot)
		// can't accidentally make two different option sets collide.
		/** @type {string} */
		this._cacheSalt = JSON.stringify([
			toCacheKeyValue(options.filename),
			toCacheKeyValue(options.append),
			toCacheKeyValue(this.moduleFilenameTemplate),
			toCacheKeyValue(this.fallbackModuleFilenameTemplate),
			toCacheKeyValue(this.namespace),
			options.module !== false,
			options.columns !== false,
			Boolean(options.noSources),
			Boolean(options.debugIds),
			options.sourceRoot || "",
			toCacheKeyValue(options.ignoreList),
			options.publicPath || "",
			options.fileContext || ""
		]);
	}

	/**
	 * Applies the plugin by registering its hooks on the compiler.
	 * @param {Compiler} compiler compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.validate.tap(PLUGIN_NAME, () => {
			compiler.validate(
				() => require("../schemas/plugins/SourceMapDevToolPlugin.json"),
				this.options,
				{
					name: "SourceMap DevTool Plugin",
					baseDataPath: "options"
				},
				(options) =>
					require("../schemas/plugins/SourceMapDevToolPlugin.check")(options)
			);
		});

		const outputFs =
			/** @type {OutputFileSystem} */
			(compiler.outputFileSystem);
		const sourceMapFilename = this.sourceMapFilename;
		const sourceMappingURLComment = this.sourceMappingURLComment;
		const moduleFilenameTemplate = this.moduleFilenameTemplate;
		const namespace = this.namespace;
		const fallbackModuleFilenameTemplate = this.fallbackModuleFilenameTemplate;
		const requestShortener = compiler.requestShortener;
		const options = this.options;
		options.test = options.test || CSS_AND_JS_MODULE_EXTENSIONS_REGEXP;

		/** @type {(filename: string) => boolean} */
		const matchObject = ModuleFilenameHelpers.matchObject.bind(
			undefined,
			options
		);

		compiler.hooks.compilation.tap(PLUGIN_NAME, (compilation) => {
			new SourceMapDevToolModuleOptionsPlugin(options).apply(compilation);

			// All SourceMapDevToolPlugin instances on the same compilation share
			// a registry of pristine asset sources, so the second instance to
			// run can still recover the original map after the first instance
			// has replaced the asset with a `RawSource`. The registry lives on a
			// module-scoped `WeakMap` keyed by compilation so it is released
			// automatically and never pollutes the compilation object.
			const originalSources = getOriginalSourceRegistry(compilation);

			compilation.hooks.processAssets.tapAsync(
				{
					name: PLUGIN_NAME,
					stage: Compilation.PROCESS_ASSETS_STAGE_DEV_TOOLING,
					additionalAssets: true
				},
				(assets, callback) => {
					const chunkGraph = compilation.chunkGraph;
					const cache = compilation.getCache(PLUGIN_NAME);
					/** @type {Map<string | Module, string>} */
					const moduleToSourceNameMapping = new Map();
					const reportProgress =
						ProgressPlugin.getReporter(compilation.compiler) || (() => {});

					/** @type {Map<string, Chunk>} */
					const fileToChunk = new Map();
					for (const chunk of compilation.chunks) {
						for (const file of chunk.files) {
							fileToChunk.set(file, chunk);
						}
						for (const file of chunk.auxiliaryFiles) {
							fileToChunk.set(file, chunk);
						}
					}

					/** @type {string[]} */
					const files = [];
					for (const file of Object.keys(assets)) {
						if (matchObject(file)) {
							files.push(file);
						}
					}

					reportProgress(0);
					/** @type {SourceMapTask[]} */
					const tasks = [];
					let fileIndex = 0;

					// Shared deduplication set for `Source#clearCache` calls below.
					// Webpack chunks routinely share module-level `CachedSource`
					// instances. A per-call WeakSet would re-walk those shared
					// subtrees once per chunk — 50 chunks × thousands of shared
					// modules in dev/non-minified setups — and worse, every
					// chunk's `sourceAndMap` would have to recompute the cleared
					// caches, churning allocations (measured: +700 MB peak RSS,
					// +6 s wall time on a 50×1000 synthetic build).
					//
					// Sharing one set lets each shared subtree be walked exactly
					// once. The trade-off is that subsequent chunks' `sourceAndMap`
					// calls can repopulate a shared module's `_cachedMaps` after
					// its own clear was skipped (because the module is already in
					// the visited set), leaving at most one populated cache entry
					// per shared module at the end of the run — bounded to a few
					// MB even at the scale of #20961. That's strictly preferable
					// to the alternative's hundreds of MB of transient peak RSS.
					const clearCacheVisited = new WeakSet();

					asyncLib.each(
						files,
						(file, callback) => {
							const asset =
								/** @type {Readonly<Asset>} */
								(compilation.getAsset(file));

							const chunk = fileToChunk.get(file);
							const sourceMapNamespace = compilation.getPath(this.namespace, {
								chunk
							});

							// The cache item identifier must include the per-instance
							// salt so two SourceMapDevToolPlugin instances that target
							// the same `file` don't collide in the persistent cache —
							// they'd otherwise write different content to the same key
							// and invalidate every pack on each build. We encode via
							// `JSON.stringify` so that special characters (e.g. `|`)
							// in an asset filename can't be spoofed to collide with the
							// salt portion of the identifier.
							const cacheItem = cache.getItemCache(
								JSON.stringify([file, this._cacheSalt]),
								cache.mergeEtags(
									cache.getLazyHashedEtag(asset.source),
									sourceMapNamespace
								)
							);

							cacheItem.get((err, cacheEntry) => {
								if (err) {
									return callback(err);
								}
								/**
								 * If presented in cache, reassigns assets. Cache assets already have source maps.
								 */
								if (cacheEntry) {
									// Pin the still-unwrapped asset source in the registry
									// before `compilation.updateAsset` replaces it. This is a
									// pointer assignment — no source-map extraction work — and
									// it lets a subsequent SourceMapDevToolPlugin instance
									// extract the original map on demand even though the
									// persistent cache hit lets us skip processing here.
									if (!originalSources.has(file)) {
										originalSources.set(file, asset.source);
									}

									const { assets, assetsInfo } = cacheEntry;
									for (const cachedFile of Object.keys(assets)) {
										if (cachedFile === file) {
											compilation.updateAsset(
												cachedFile,
												assets[cachedFile],
												assetsInfo[cachedFile]
											);
										} else {
											compilation.emitAsset(
												cachedFile,
												assets[cachedFile],
												assetsInfo[cachedFile]
											);
										}
										/**
										 * Add file to chunk, if not presented there
										 */
										if (cachedFile !== file && chunk !== undefined) {
											chunk.auxiliaryFiles.add(cachedFile);
										}
									}

									reportProgress(
										(0.5 * ++fileIndex) / files.length,
										file,
										"restored cached SourceMap"
									);

									return callback();
								}

								reportProgress(
									(0.5 * fileIndex) / files.length,
									file,
									"generate SourceMap"
								);

								/** @type {SourceMapTask | undefined} */
								const task = getTaskForFile(
									file,
									asset.source,
									asset.info,
									{
										module: options.module,
										columns: options.columns
									},
									compilation,
									cacheItem,
									originalSources
								);

								// Release the per-instance caches that `sourceAndMap`
								// just populated. The composed map (and, for
								// `SourceMapSource`, the parsed `_sourceMapAsObject` /
								// `_innerSourceMapAsObject`) otherwise sit on the
								// CachedSource — and every shared child — until phase
								// 2 replaces the asset, which is what causes the OOM
								// spike on builds with thousands of chunks
								// (webpack#20961). Keep `source` since downstream
								// consumers reading the original asset still need it;
								// `hash`/`size` default to retained because they're
								// cheap to keep but expensive to rebuild.
								// `clearCacheVisited` is shared across every call (see
								// its declaration above for the rationale).
								//
								// Target `task.mapSource` (not `asset.source`): when
								// `extractSourceAndMap` falls back to the pinned
								// original (the current asset is a `RawSource` left
								// by an earlier plugin instance), the `sourceAndMap`
								// call populated the original's caches, not the
								// current asset's.
								//
								// Feature-detected: `clearCache` landed in
								// `webpack-sources` 3.5, but `compilation.assets` may
								// hold `Source`-like instances from a third-party
								// plugin built against an older copy of
								// `webpack-sources` (or a hand-rolled implementation).
								// Calling it unconditionally would throw on those.
								if (task && typeof task.mapSource.clearCache === "function") {
									task.mapSource.clearCache(
										{
											maps: true,
											source: false,
											parsedMap: true
										},
										clearCacheVisited
									);
								}

								if (task) {
									const modules = task.modules;

									for (let idx = 0; idx < modules.length; idx++) {
										const module = modules[idx];

										if (
											typeof module === "string" &&
											/^(?:data|https?):/.test(module)
										) {
											moduleToSourceNameMapping.set(module, module);
											continue;
										}

										if (!moduleToSourceNameMapping.get(module)) {
											moduleToSourceNameMapping.set(
												module,
												ModuleFilenameHelpers.createFilename(
													module,
													{
														moduleFilenameTemplate,
														namespace: sourceMapNamespace
													},
													{
														requestShortener,
														chunkGraph,
														hashFunction: compilation.outputOptions.hashFunction
													}
												)
											);
										}
									}

									tasks.push(task);
								}

								reportProgress(
									(0.5 * ++fileIndex) / files.length,
									file,
									"generated SourceMap"
								);

								callback();
							});
						},
						(err) => {
							if (err) {
								return callback(err);
							}

							reportProgress(0.5, "resolve sources");
							/** @type {Set<string>} */
							const usedNamesSet = new Set(moduleToSourceNameMapping.values());
							/** @type {Set<string>} */
							const conflictDetectionSet = new Set();

							/**
							 * all modules in defined order (longest identifier first)
							 * @type {(string | Module)[]}
							 */
							const allModules = [...moduleToSourceNameMapping.keys()].sort(
								(a, b) => {
									const ai = typeof a === "string" ? a : a.identifier();
									const bi = typeof b === "string" ? b : b.identifier();
									return ai.length - bi.length;
								}
							);

							// find modules with conflicting source names
							for (let idx = 0; idx < allModules.length; idx++) {
								const module = allModules[idx];
								let sourceName =
									/** @type {string} */
									(moduleToSourceNameMapping.get(module));
								let hasName = conflictDetectionSet.has(sourceName);
								if (!hasName) {
									conflictDetectionSet.add(sourceName);
									continue;
								}

								// try the fallback name first
								sourceName = ModuleFilenameHelpers.createFilename(
									module,
									{
										moduleFilenameTemplate: fallbackModuleFilenameTemplate,
										namespace
									},
									{
										requestShortener,
										chunkGraph,
										hashFunction: compilation.outputOptions.hashFunction
									}
								);
								hasName = usedNamesSet.has(sourceName);
								if (!hasName) {
									moduleToSourceNameMapping.set(module, sourceName);
									usedNamesSet.add(sourceName);
									continue;
								}

								// otherwise just append stars until we have a valid name
								while (hasName) {
									sourceName += "*";
									hasName = usedNamesSet.has(sourceName);
								}
								moduleToSourceNameMapping.set(module, sourceName);
								usedNamesSet.add(sourceName);
							}

							let taskIndex = 0;

							asyncLib.each(
								tasks,
								(task, callback) => {
									/** @type {Record<string, Source>} */
									const assets = Object.create(null);
									/** @type {Record<string, AssetInfo | undefined>} */
									const assetsInfo = Object.create(null);
									const file = task.file;
									const chunk = fileToChunk.get(file);
									const sourceMap = task.sourceMap;
									const source = task.source;
									const modules = task.modules;

									reportProgress(
										0.5 + (0.5 * taskIndex) / tasks.length,
										file,
										"attach SourceMap"
									);

									const moduleFilenames =
										/** @type {string[]} */
										(modules.map((m) => moduleToSourceNameMapping.get(m)));
									// We deliberately do NOT mutate `sourceMap` in place: the
									// task's `sourceMap` reference may be shared with a
									// `SourceMapSource` whose internal map cache is the same
									// object (webpack-sources keeps it cached). A second
									// `SourceMapDevToolPlugin` instance that reads the original
									// source through the registry would otherwise see our
									// rewrites. Instead we build a fresh `outputSourceMap` for
									// the .map file and leave the original alone.
									/** @type {number[] | undefined} */
									let ignoreList;
									if (options.ignoreList) {
										const list = moduleFilenames.reduce(
											/** @type {(acc: number[], sourceName: string, idx: number) => number[]} */ (
												(acc, sourceName, idx) => {
													const rule = /** @type {Rules} */ (
														options.ignoreList
													);
													if (
														ModuleFilenameHelpers.matchPart(sourceName, rule)
													) {
														acc.push(idx);
													}
													return acc;
												}
											),
											[]
										);
										if (list.length > 0) ignoreList = list;
									}

									const usesContentHash =
										sourceMapFilename &&
										CONTENT_HASH_DETECT_REGEXP.test(sourceMapFilename);

									resetRegexpState(CONTENT_HASH_DETECT_REGEXP);

									let outputFile = file;
									// If SourceMap and asset uses contenthash, avoid a circular dependency by hiding hash in `file`
									if (usesContentHash && task.assetInfo.contenthash) {
										const contenthash = task.assetInfo.contenthash;
										const pattern = Array.isArray(contenthash)
											? contenthash.map(quoteMeta).join("|")
											: quoteMeta(contenthash);
										outputFile = outputFile.replace(
											new RegExp(pattern, "g"),
											(m) => "x".repeat(m.length)
										);
									}

									/** @type {false | SourceMappingURLComment} */
									let currentSourceMappingURLComment = sourceMappingURLComment;
									const cssExtensionDetected =
										CSS_EXTENSION_DETECT_REGEXP.test(file);
									resetRegexpState(CSS_EXTENSION_DETECT_REGEXP);
									if (
										currentSourceMappingURLComment !== false &&
										typeof currentSourceMappingURLComment !== "function" &&
										cssExtensionDetected
									) {
										currentSourceMappingURLComment =
											currentSourceMappingURLComment.replace(
												URL_FORMATTING_REGEXP,
												"\n/*$1*/"
											);
									}

									/** @type {string | undefined} */
									let debugIdValue;
									if (options.debugIds) {
										const debugId = generateDebugId(source, outputFile);
										debugIdValue = debugId;

										const debugIdComment = `\n//# debugId=${debugId}`;
										if (currentSourceMappingURLComment === false) {
											currentSourceMappingURLComment = debugIdComment;
										} else if (
											typeof currentSourceMappingURLComment === "function"
										) {
											// Wrap the user's append function so the debug-id
											// comment is prepended at call time. Template-string
											// concatenation would coerce the function to a string
											// and lose its dynamic behavior.
											const wrappedFn = currentSourceMappingURLComment;
											currentSourceMappingURLComment = (pathData, assetInfo) =>
												`${debugIdComment}${wrappedFn(pathData, assetInfo)}`;
										} else {
											currentSourceMappingURLComment = `${debugIdComment}${currentSourceMappingURLComment}`;
										}
									}

									/** @type {RawSourceMap} */
									const outputSourceMap = {
										...sourceMap,
										sources: moduleFilenames,
										sourceRoot: options.sourceRoot || "",
										file: outputFile
									};
									if (ignoreList !== undefined) {
										outputSourceMap.ignoreList = ignoreList;
									}
									if (options.noSources) {
										outputSourceMap.sourcesContent = undefined;
									}
									if (debugIdValue !== undefined) {
										outputSourceMap.debugId = debugIdValue;
									}

									if (sourceMapFilename) {
										// External `.map` file: hold the serialized map as a
										// `Buffer` instead of a V8 string. `RawSource` accepts
										// a buffer directly, and the emitted asset stays in
										// `compilation.assets` until the build finishes — so
										// storing the bytes off the V8 heap (where Buffers
										// live, accounted as `external` memory) avoids keeping
										// a large V8 string alive for the rest of the build
										// and reduces heap pressure on `--max-old-space-size`.
										const sourceMapBuffer = Buffer.from(
											JSON.stringify(outputSourceMap),
											"utf8"
										);
										const filename = file;
										const sourceMapContentHash = usesContentHash
											? createHash(compilation.outputOptions.hashFunction)
													.update(sourceMapBuffer)
													.digest("hex")
											: undefined;

										const pathParams = {
											chunk,
											filename: options.fileContext
												? relative(
														outputFs,
														`/${options.fileContext}`,
														`/${filename}`
													)
												: filename,
											contentHash: sourceMapContentHash
										};
										const { path: sourceMapFile, info: sourceMapInfo } =
											compilation.getPathWithInfo(
												sourceMapFilename,
												pathParams
											);
										const sourceMapUrl = options.publicPath
											? options.publicPath + sourceMapFile
											: relative(
													outputFs,
													dirname(outputFs, `/${file}`),
													`/${sourceMapFile}`
												);
										/** @type {Source} */
										let asset = new RawSource(source);
										if (currentSourceMappingURLComment !== false) {
											// Add source map url to compilation asset, if currentSourceMappingURLComment is set
											asset = new ConcatSource(
												asset,
												compilation.getPath(currentSourceMappingURLComment, {
													url: sourceMapUrl,
													...pathParams
												})
											);
										}
										// Preserve any existing related.sourceMap entries from
										// earlier SourceMapDevToolPlugin runs on the same asset so
										// that all generated maps remain discoverable via asset
										// info (the schema allows string or string[]).
										const existingSourceMap =
											task.assetInfo.related &&
											task.assetInfo.related.sourceMap;
										/** @type {string | string[]} */
										let relatedSourceMap;
										if (
											existingSourceMap === undefined ||
											existingSourceMap === null
										) {
											relatedSourceMap = sourceMapFile;
										} else if (Array.isArray(existingSourceMap)) {
											relatedSourceMap = existingSourceMap.includes(
												sourceMapFile
											)
												? existingSourceMap
												: [...existingSourceMap, sourceMapFile];
										} else {
											relatedSourceMap =
												existingSourceMap === sourceMapFile
													? existingSourceMap
													: [existingSourceMap, sourceMapFile];
										}
										const assetInfo = {
											related: { sourceMap: relatedSourceMap }
										};
										assets[file] = asset;
										assetsInfo[file] = assetInfo;
										compilation.updateAsset(file, asset, assetInfo);
										// Add source map file to compilation assets and chunk files
										const sourceMapAsset = new RawSource(sourceMapBuffer);
										const sourceMapAssetInfo = {
											...sourceMapInfo,
											development: true
										};
										assets[sourceMapFile] = sourceMapAsset;
										assetsInfo[sourceMapFile] = sourceMapAssetInfo;
										compilation.emitAsset(
											sourceMapFile,
											sourceMapAsset,
											sourceMapAssetInfo
										);
										if (chunk !== undefined) {
											chunk.auxiliaryFiles.add(sourceMapFile);
										}
									} else {
										if (currentSourceMappingURLComment === false) {
											throw new Error(
												`${PLUGIN_NAME}: append can't be false when no filename is provided`
											);
										}
										if (typeof currentSourceMappingURLComment === "function") {
											throw new Error(
												`${PLUGIN_NAME}: append can't be a function when no filename is provided`
											);
										}
										// Inline data-URL form: `[map]` gets the raw JSON, `[url]`
										// gets the same JSON base64-encoded. `URL_COMMENT_REGEXP`
										// is a `/g` regex, so a user `append` template with more
										// than one `[url]` placeholder would otherwise re-encode
										// the same JSON per match. Pre-compute both once.
										const sourceMapString = JSON.stringify(outputSourceMap);
										const sourceMapBase64 = Buffer.from(
											sourceMapString,
											"utf8"
										).toString("base64");
										/**
										 * Add source map as data url to asset
										 */
										const asset = new ConcatSource(
											new RawSource(source),
											currentSourceMappingURLComment
												.replace(MAP_URL_COMMENT_REGEXP, () => sourceMapString)
												.replace(
													URL_COMMENT_REGEXP,
													() =>
														`data:application/json;charset=utf-8;base64,${sourceMapBase64}`
												)
										);
										assets[file] = asset;
										assetsInfo[file] = undefined;
										compilation.updateAsset(file, asset);
									}

									task.cacheItem.store({ assets, assetsInfo }, (err) => {
										reportProgress(
											0.5 + (0.5 * ++taskIndex) / tasks.length,
											task.file,
											"attached SourceMap"
										);

										if (err) {
											return callback(err);
										}
										callback();
									});
								},
								(err) => {
									reportProgress(1);
									callback(err);
								}
							);
						}
					);
				}
			);
		});
	}
}

module.exports = SourceMapDevToolPlugin;