[v3.0] Better sourcemap emission

cli/run/build.ts

@@ -5,7 +5,6 @@ import type { MergedRollupOptions } from '../../src/rollup/types';
 import { bold, cyan, green } from '../../src/utils/colors';
 import { errOnlyInlineSourcemapsForStdout } from '../../src/utils/error';
 import relativeId from '../../src/utils/relativeId';
-import { SOURCEMAPPING_URL } from '../../src/utils/sourceMappingURL';
 import { handleError, stderr } from '../logging';
 import type { BatchWarnings } from './batchWarnings';
 import { printTimings } from './timings';
@@ -37,20 +36,10 @@ export default async function build(
 		if (output.sourcemap && output.sourcemap !== 'inline') {
 			handleError(errOnlyInlineSourcemapsForStdout());
 		}
-
 		const { output: outputs } = await bundle.generate(output);
 		for (const file of outputs) {
-			let source: string | Uint8Array;
-			if (file.type === 'asset') {
-				source = file.source;
-			} else {
-				source = file.code;
-				if (output.sourcemap === 'inline') {
-					source += `\n//# ${SOURCEMAPPING_URL}=${file.map!.toUrl()}\n`;
-				}
-			}
 			if (outputs.length > 1) process.stdout.write(`\n${cyan(bold(`//→ ${file.fileName}:`))}\n`);
-			process.stdout.write(source as Buffer);
+			process.stdout.write(file.type === 'asset' ? file.source : file.code);
 		}
 		if (!silent) {
 			warnings.flush();

src/rollup/rollup.ts

@@ -15,9 +15,8 @@ import { catchUnfinishedHookActions } from '../utils/hookActions';
 import { normalizeInputOptions } from '../utils/options/normalizeInputOptions';
 import { normalizeOutputOptions } from '../utils/options/normalizeOutputOptions';
 import type { GenericConfigObject } from '../utils/options/options';
-import { basename, dirname, resolve } from '../utils/path';
+import { dirname, resolve } from '../utils/path';
 import { ANONYMOUS_OUTPUT_PLUGIN_PREFIX, ANONYMOUS_PLUGIN_PREFIX } from '../utils/pluginUtils';
-import { SOURCEMAPPING_URL } from '../utils/sourceMappingURL';
 import { getTimings, initialiseTimers, timeEnd, timeStart } from '../utils/timers';
 import type {
 	NormalizedInputOptions,
@@ -282,31 +281,7 @@ async function writeOutputFile(
 	// 'recursive: true' does not throw if the folder structure, or parts of it, already exist
 	await fs.mkdir(dirname(fileName), { recursive: true });
 
-	let writeSourceMapPromise: Promise<void> | undefined;
-	let source: string | Uint8Array;
-	if (outputFile.type === 'asset') {
-		source = outputFile.source;
-	} else {
-		source = outputFile.code;
-		if (outputOptions.sourcemap && outputFile.map) {
-			let url: string;
-			if (outputOptions.sourcemap === 'inline') {
-				url = outputFile.map.toUrl();
-			} else {
-				const { sourcemapBaseUrl } = outputOptions;
-				const sourcemapFileName = `${basename(outputFile.fileName)}.map`;
-				url = sourcemapBaseUrl
-					? new URL(sourcemapFileName, sourcemapBaseUrl).toString()
-					: sourcemapFileName;
-				writeSourceMapPromise = fs.writeFile(`${fileName}.map`, outputFile.map.toString());
-			}
-			if (outputOptions.sourcemap !== 'hidden') {
-				source += `//# ${SOURCEMAPPING_URL}=${url}\n`;
-			}
-		}
-	}
-
-	return Promise.all([fs.writeFile(fileName, source), writeSourceMapPromise]);
+	return fs.writeFile(fileName, outputFile.type === 'asset' ? outputFile.source : outputFile.code);
 }
 
 /**

src/utils/renderChunks.ts

@@ -19,7 +19,8 @@ import {
 	replacePlaceholdersWithDefaultAndGetContainedPlaceholders,
 	replaceSinglePlaceholder
 } from './hashPlaceholders';
-import { normalize, resolve } from './path';
+import { basename, normalize, resolve } from './path';
+import { SOURCEMAPPING_URL } from './sourceMappingURL';
 import { timeEnd, timeStart } from './timers';
 
 interface HashResult {
@@ -70,7 +71,9 @@ export async function renderChunks(
 		renderedChunksByPlaceholder,
 		hashesByPlaceholder,
 		outputBundle,
-		nonHashedChunksWithPlaceholders
+		nonHashedChunksWithPlaceholders,
+		pluginDriver,
+		outputOptions
 	);
 
 	timeEnd('transform chunks', 2);
@@ -286,20 +289,45 @@ function addChunksToBundle(
 	renderedChunksByPlaceholder: Map<string, RenderedChunkWithPlaceholders>,
 	hashesByPlaceholder: Map<string, string>,
 	outputBundle: OutputBundleWithPlaceholders,
-	nonHashedChunksWithPlaceholders: RenderedChunkWithPlaceholders[]
+	nonHashedChunksWithPlaceholders: RenderedChunkWithPlaceholders[],
+	pluginDriver: PluginDriver,
+	options: NormalizedOutputOptions
 ) {
 	for (const { chunk, code, fileName, map } of renderedChunksByPlaceholder.values()) {
-		const updatedCode = replacePlaceholders(code, hashesByPlaceholder);
+		let updatedCode = replacePlaceholders(code, hashesByPlaceholder);
 		const finalFileName = replacePlaceholders(fileName, hashesByPlaceholder);
 		if (map) {
 			map.file = replacePlaceholders(map.file, hashesByPlaceholder);
+			updatedCode += emitSourceMapAndGetComment(finalFileName, map, pluginDriver, options);
 		}
 		outputBundle[finalFileName] = chunk.generateOutputChunk(updatedCode, map, hashesByPlaceholder);
 	}
 	for (const { chunk, code, fileName, map } of nonHashedChunksWithPlaceholders) {
-		const updatedCode = hashesByPlaceholder.size
+		let updatedCode = hashesByPlaceholder.size
 			? replacePlaceholders(code, hashesByPlaceholder)
 			: code;
+		if (map) {
+			updatedCode += emitSourceMapAndGetComment(fileName, map, pluginDriver, options);
+		}
 		outputBundle[fileName] = chunk.generateOutputChunk(updatedCode, map, hashesByPlaceholder);
 	}
 }
+
+function emitSourceMapAndGetComment(
+	fileName: string,
+	map: SourceMap,
+	pluginDriver: PluginDriver,
+	{ sourcemap, sourcemapBaseUrl }: NormalizedOutputOptions
+) {
+	let url: string;
+	if (sourcemap === 'inline') {
+		url = map.toUrl();
+	} else {
+		const sourcemapFileName = `${basename(fileName)}.map`;
+		url = sourcemapBaseUrl
+			? new URL(sourcemapFileName, sourcemapBaseUrl).toString()
+			: sourcemapFileName;
+		pluginDriver.emitFile({ fileName: `${fileName}.map`, source: map.toString(), type: 'asset' });
+	}
+	return sourcemap === 'hidden' ? '' : `//# ${SOURCEMAPPING_URL}=${url}\n`;
+}

test/function/samples/sourcemap-inline-generatebundle/_config.js

@@ -0,0 +1,26 @@
+const assert = require('assert');
+
+module.exports = {
+	description: 'includes inline sourcemap comments in generateBundle hook',
+	options: {
+		plugins: [
+			{
+				name: 'test',
+				generateBundle(options, bundle) {
+					assert.deepStrictEqual(Object.keys(bundle), ['main.js']);
+					assert.strictEqual(
+						bundle['main.js'].code,
+						`'use strict';
+
+var main = 42;
+
+module.exports = main;
+//# sourceMappingURL=data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoibWFpbi5qcyIsInNvdXJjZXMiOlsibWFpbi5qcyJdLCJzb3VyY2VzQ29udGVudCI6WyJleHBvcnQgZGVmYXVsdCA0MjtcbiJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiOztBQUFBLFdBQWUsRUFBRTs7OzsifQ==
+`
+					);
+				}
+			}
+		],
+		output: { sourcemap: 'inline' }
+	}
+};

test/function/samples/sourcemap-inline-generatebundle/main.js

@@ -0,0 +1 @@
+export default 42;

test/function/samples/sourcemap-true-generatebundle/_config.js

@@ -0,0 +1,33 @@
+const assert = require('assert');
+
+module.exports = {
+	description: 'emits sourcemaps before generateBundle hook',
+	options: {
+		plugins: [
+			{
+				name: 'test',
+				generateBundle(options, bundle) {
+					assert.deepStrictEqual(Object.keys(bundle), ['main.js', 'main.js.map']);
+					assert.strictEqual(
+						bundle['main.js'].code,
+						`'use strict';
+
+var main = 42;
+
+module.exports = main;
+//# sourceMappingURL=main.js.map
+`
+					);
+					assert.deepStrictEqual(bundle['main.js.map'], {
+						fileName: 'main.js.map',
+						name: undefined,
+						source:
+							'{"version":3,"file":"main.js","sources":["main.js"],"sourcesContent":["export default 42;\\n"],"names":[],"mappings":";;AAAA,WAAe,EAAE;;;;"}',
+						type: 'asset'
+					});
+				}
+			}
+		],
+		output: { sourcemap: true }
+	}
+};

test/function/samples/sourcemap-true-generatebundle/main.js

@@ -0,0 +1 @@
+export default 42;

test/sourcemaps/samples/existing-external-sourcemaps-combined/_config.js

@@ -3,6 +3,6 @@ const assert = require('assert');
 module.exports = {
 	description: 'removes sourcemap comments',
 	async test(code) {
-		assert.ok(!code.includes('sourceMappingURL'));
+		assert.ok(!code.includes('sourceMappingURL=main.js.map'));
 	}
 };

test/sourcemaps/samples/existing-inline-sourcemaps-combined/_config.js

@@ -3,6 +3,6 @@ const assert = require('assert');
 module.exports = {
 	description: 'removes existing inline sourcemaps',
 	async test(code) {
-		assert.ok(!code.includes('sourceMappingURL'));
+		assert.ok(!code.includes('sourceMappingURL=data'));
 	}
 };