Use export mode "auto" by default when preserving modules

LICENSE.md

@@ -382,7 +382,7 @@ Repository: sindresorhus/pretty-bytes
 ## pretty-ms
 License: MIT
 By: Sindre Sorhus
-Repository: git+https://github.com/sindresorhus/pretty-ms.git
+Repository: sindresorhus/pretty-ms
 
 ---------------------------------------
 

cli/run/batchWarnings.ts

@@ -82,13 +82,6 @@ const immediateHandlers: {
 		stderr(
 			`Creating a browser bundle that depends on ${detail}. You might need to include https://www.npmjs.com/package/rollup-plugin-node-builtins`
 		);
-	},
-
-	MIXED_EXPORTS: () => {
-		title('Mixing named and default exports');
-		stderr(
-			`Consumers of your bundle will have to use bundle['default'] to access the default export, which may not be what you want. Use \`output.exports: 'named'\` to disable this warning`
-		);
 	}
 };
 
@@ -106,27 +99,19 @@ const deferredHandlers: {
 		}
 	},
 
-	UNUSED_EXTERNAL_IMPORT(warnings) {
-		title('Unused external imports');
-		for (const warning of warnings) {
-			stderr(`${warning.names} imported from external module '${warning.source}' but never used`);
-		}
+	EMPTY_BUNDLE(warnings) {
+		title(
+			`Generated${warnings.length === 1 ? ' an' : ''} empty ${
+				warnings.length > 1 ? 'chunks' : 'chunk'
+			}`
+		);
+		stderr(warnings.map(warning => warning.chunkName!).join(', '));
 	},
 
-	UNRESOLVED_IMPORT(warnings) {
-		title('Unresolved dependencies');
-		info('https://rollupjs.org/guide/en/#warning-treating-module-as-external-dependency');
-
-		const dependencies = new Map();
-		for (const warning of warnings) {
-			if (!dependencies.has(warning.source)) dependencies.set(warning.source, []);
-			dependencies.get(warning.source).push(warning.importer);
-		}
-
-		for (const dependency of dependencies.keys()) {
-			const importers = dependencies.get(dependency);
-			stderr(`${tc.bold(dependency)} (imported by ${importers.join(', ')})`);
-		}
+	EVAL(warnings) {
+		title('Use of eval is strongly discouraged');
+		info('https://rollupjs.org/guide/en/#avoiding-eval');
+		showTruncatedWarnings(warnings);
 	},
 
 	MISSING_EXPORT(warnings) {
@@ -140,21 +125,32 @@ const deferredHandlers: {
 		}
 	},
 
-	THIS_IS_UNDEFINED(warnings) {
-		title('`this` has been rewritten to `undefined`');
-		info('https://rollupjs.org/guide/en/#error-this-is-undefined');
-		showTruncatedWarnings(warnings);
-	},
-
-	EVAL(warnings) {
-		title('Use of eval is strongly discouraged');
-		info('https://rollupjs.org/guide/en/#avoiding-eval');
-		showTruncatedWarnings(warnings);
+	MISSING_GLOBAL_NAME(warnings) {
+		title(`Missing global variable ${warnings.length > 1 ? 'names' : 'name'}`);
+		stderr(
+			`Use output.globals to specify browser global variable names corresponding to external modules`
+		);
+		for (const warning of warnings) {
+			stderr(`${tc.bold(warning.source!)} (guessing '${warning.guess}')`);
+		}
 	},
 
-	NON_EXISTENT_EXPORT(warnings) {
-		title(`Import of non-existent ${warnings.length > 1 ? 'exports' : 'export'}`);
-		showTruncatedWarnings(warnings);
+	MIXED_EXPORTS: (warnings) => {
+		title('Mixing named and default exports');
+		info(`https://rollupjs.org/guide/en/#output-exports`);
+		stderr(
+			tc.bold('The following entry modules are using named and default exports together:')
+		);
+		const displayedWarnings = warnings.length > 5 ? warnings.slice(0, 3) : warnings;
+		for (const warning of displayedWarnings) {
+			stderr(relativeId(warning.id!));
+		}
+		if (displayedWarnings.length < warnings.length) {
+			stderr(`...and ${warnings.length - displayedWarnings.length} other entry modules`);
+		}
+		stderr(
+			`\nConsumers of your bundle will have to use chunk['default'] to access their default export, which may not be what you want. Use \`output.exports: 'named'\` to disable this warning`
+		);
 	},
 
 	NAMESPACE_CONFLICT(warnings) {
@@ -170,30 +166,9 @@ const deferredHandlers: {
 		}
 	},
 
-	MISSING_GLOBAL_NAME(warnings) {
-		title(`Missing global variable ${warnings.length > 1 ? 'names' : 'name'}`);
-		stderr(
-			`Use output.globals to specify browser global variable names corresponding to external modules`
-		);
-		for (const warning of warnings) {
-			stderr(`${tc.bold(warning.source!)} (guessing '${warning.guess}')`);
-		}
-	},
-
-	SOURCEMAP_BROKEN(warnings) {
-		title(`Broken sourcemap`);
-		info('https://rollupjs.org/guide/en/#warning-sourcemap-is-likely-to-be-incorrect');
-
-		const plugins = Array.from(new Set(warnings.map(w => w.plugin).filter(Boolean)));
-		const detail =
-			plugins.length > 1
-				? ` (such as ${plugins
-						.slice(0, -1)
-						.map(p => `'${p}'`)
-						.join(', ')} and '${plugins.slice(-1)}')`
-				: ` (such as '${plugins[0]}')`;
-
-		stderr(`Plugins that transform code${detail} should generate accompanying sourcemaps`);
+	NON_EXISTENT_EXPORT(warnings) {
+		title(`Import of non-existent ${warnings.length > 1 ? 'exports' : 'export'}`);
+		showTruncatedWarnings(warnings);
 	},
 
 	PLUGIN_WARNING(warnings) {
@@ -222,13 +197,49 @@ const deferredHandlers: {
 		}
 	},
 
-	EMPTY_BUNDLE(warnings) {
-		title(
-			`Generated${warnings.length === 1 ? ' an' : ''} empty ${
-				warnings.length > 1 ? 'chunks' : 'chunk'
-			}`
-		);
-		stderr(warnings.map(warning => warning.chunkName!).join(', '));
+	SOURCEMAP_BROKEN(warnings) {
+		title(`Broken sourcemap`);
+		info('https://rollupjs.org/guide/en/#warning-sourcemap-is-likely-to-be-incorrect');
+
+		const plugins = Array.from(new Set(warnings.map(w => w.plugin).filter(Boolean)));
+		const detail =
+			plugins.length > 1
+				? ` (such as ${plugins
+				.slice(0, -1)
+				.map(p => `'${p}'`)
+				.join(', ')} and '${plugins.slice(-1)}')`
+				: ` (such as '${plugins[0]}')`;
+
+		stderr(`Plugins that transform code${detail} should generate accompanying sourcemaps`);
+	},
+
+	THIS_IS_UNDEFINED(warnings) {
+		title('`this` has been rewritten to `undefined`');
+		info('https://rollupjs.org/guide/en/#error-this-is-undefined');
+		showTruncatedWarnings(warnings);
+	},
+
+	UNRESOLVED_IMPORT(warnings) {
+		title('Unresolved dependencies');
+		info('https://rollupjs.org/guide/en/#warning-treating-module-as-external-dependency');
+
+		const dependencies = new Map();
+		for (const warning of warnings) {
+			if (!dependencies.has(warning.source)) dependencies.set(warning.source, []);
+			dependencies.get(warning.source).push(warning.importer);
+		}
+
+		for (const dependency of dependencies.keys()) {
+			const importers = dependencies.get(dependency);
+			stderr(`${tc.bold(dependency)} (imported by ${importers.join(', ')})`);
+		}
+	},
+
+	UNUSED_EXTERNAL_IMPORT(warnings) {
+		title('Unused external imports');
+		for (const warning of warnings) {
+			stderr(`${warning.names} imported from external module '${warning.source}' but never used`);
+		}
 	}
 };
 

docs/01-command-line-reference.md

@@ -187,6 +187,22 @@ export default commandLineArgs => {
 
 If you now run `rollup --config --configDebug`, the debug configuration will be used.
 
+By default, command line arguments will always override the respective values exported from a config file. If you want to change this behaviour, you can make Rollup ignore command line arguments by deleting them from the `commandLineArgs` object:
+
+```javascript
+// rollup.config.js
+export default commandLineArgs => {
+  const inputBase = commandLineArgs.input || 'main.js';
+
+  // this will make Rollup ignore the CLI argument
+  delete commandLineArgs.input;
+  return {
+    input: 'src/entries/' + inputBase,
+    output: {...}
+  }
+}
+```
+
 
 ### Command line flags
 

docs/999-big-list-of-options.md

@@ -572,6 +572,48 @@ Default: `false`
 
 Instead of creating as few chunks as possible, this mode will create separate chunks for all modules using the original module names as file names. Requires the [`output.dir`](guide/en/#outputdir) option. Tree-shaking will still be applied, suppressing files that are not used by the provided entry points or do not have side-effects when executed. This mode can be used to transform a file structure to a different module format.
 
+Note that when transforming to `cjs` or `amd` format, each file will by default be treated as an entry point with [`output.exports`](guide/en/#outputexports) set to `auto`. This means that e.g. for `cjs`, a file that only contains a default export will be rendered as
+
+```js
+// input main.js
+export default 42;
+
+// output main.js
+'use strict';
+
+var main = 42;
+
+module.exports = main;
+```
+
+assigning the value directly to `module.exports`. If someone imports this file, they will get access to the default export via
+
+```js
+const main = require('./main.js');
+console.log(main); // 42
+```
+
+As with regular entry points, files that mix default and named exports will produce warnings. You can avoid the warnings by forcing all files to use named export mode via `output.exports: "named"`. In that case, the default export needs to be accessed via the `.default` property of the export:
+
+```js
+// input main.js
+export default 42;
+
+// output main.js
+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+var main = 42;
+
+exports.default = main;
+
+// consuming file
+const main = require('./main.js');
+console.log(main.default); // 42
+```
+
+
 #### strictDeprecations
 Type: `boolean`<br>
 CLI: `--strictDeprecations`/`--no-strictDeprecations`<br>

src/Chunk.ts

@@ -619,7 +619,7 @@ export default class Chunk {
 		this.renderedSourceLength = undefined as any;
 		this.renderedHash = undefined as any;
 
-		if (this.getExportNames().length === 0 && this.getImportIds().length === 0 && this.isEmpty) {
+		if (this.isEmpty && this.getExportNames().length === 0 && this.dependencies.length === 0) {
 			const chunkName = this.getChunkName();
 			this.graph.warn({
 				chunkName,
@@ -708,7 +708,9 @@ export default class Chunk {
 				hasExports,
 				indentString: this.indentString,
 				intro: addons.intro as string,
-				isEntryModuleFacade: this.facadeModule !== null && this.facadeModule.isEntryPoint,
+				isEntryModuleFacade:
+					this.graph.preserveModules ||
+					(this.facadeModule !== null && this.facadeModule.isEntryPoint),
 				namedExportsMode: this.exportMode !== 'default',
 				outro: addons.outro as string,
 				usesTopLevelAwait,

src/finalisers/shared/getExportBlock.ts

@@ -23,6 +23,7 @@ export default function getExportBlock(
 						dep.namedExportsMode && expt.imported !== '*' && expt.imported !== 'default'
 							? `${dep.name}.${expt.imported}`
 							: dep.name;
+					break;
 				}
 			}
 		}

src/rollup/index.ts

@@ -5,7 +5,12 @@ import Graph from '../Graph';
 import { createAddons } from '../utils/addons';
 import { assignChunkIds } from '../utils/assignChunkIds';
 import commondir from '../utils/commondir';
-import { errCannotEmitFromOptionsHook, errDeprecation, error } from '../utils/error';
+import {
+	errCannotEmitFromOptionsHook,
+	errDeprecation,
+	errInvalidExportOptionValue,
+	error
+} from '../utils/error';
 import { writeFile } from '../utils/fs';
 import getExportMode from '../utils/getExportMode';
 import mergeOptions, { GenericConfigObject } from '../utils/mergeOptions';
@@ -45,6 +50,10 @@ function checkOutputOptions(options: OutputOptions) {
 			url: `https://rollupjs.org/guide/en/#output-format`
 		});
 	}
+
+	if (options.exports && !['default', 'named', 'none', 'auto'].includes(options.exports)) {
+		error(errInvalidExportOptionValue(options.exports));
+	}
 }
 
 function getAbsoluteEntryModulePaths(chunks: Chunk[]): string[] {
@@ -259,8 +268,8 @@ export default async function rollup(rawInputOptions: GenericConfigObject): Prom
 			const addons = await createAddons(outputOptions, outputPluginDriver);
 			for (const chunk of chunks) {
 				if (!inputOptions.preserveModules) chunk.generateInternalExports(outputOptions);
-				if (chunk.facadeModule && chunk.facadeModule.isEntryPoint)
-					chunk.exportMode = getExportMode(chunk, outputOptions);
+				if (inputOptions.preserveModules || (chunk.facadeModule && chunk.facadeModule.isEntryPoint))
+					chunk.exportMode = getExportMode(chunk, outputOptions, chunk.facadeModule!.id);
 			}
 			for (const chunk of chunks) {
 				chunk.preRender(outputOptions, inputBase);
@@ -403,7 +412,8 @@ function createOutput(outputBundle: Record<string, OutputChunk | OutputAsset | {
 			.map(fileName => outputBundle[fileName])
 			.filter(outputFile => Object.keys(outputFile).length > 0) as (
 			| OutputChunk
-			| OutputAsset)[]).sort((outputFileA, outputFileB) => {
+			| OutputAsset
+		)[]).sort((outputFileA, outputFileB) => {
 			const fileTypeA = getSortingFileType(outputFileA);
 			const fileTypeB = getSortingFileType(outputFileB);
 			if (fileTypeA === fileTypeB) return 0;