[v3.0] Remove implicit default export mode warning

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

@@ -1466,8 +1466,6 @@ Note: There are some tools such as Babel, TypeScript, Webpack, and `@rollup/plug
 
 In other words for those tools, you cannot create a package interface where `const lib = require("your-lib")` yields the same as `import lib from "your-lib"`. With named export mode however, `const {lib} = require("your-lib")` will be equivalent to `import {lib} from "your-lib"`.
 
-To alert you to this, Rollup will generate a warning when you encounter such a situation and did not select an explicit value for `output.exports`.
-
 #### output.externalLiveBindings
 
 Type: `boolean`<br> CLI: `--externalLiveBindings`/`--no-externalLiveBindings`<br> Default: `true`

src/Chunk.ts

@@ -332,7 +332,6 @@ export default class Chunk {
 			this.exportMode = getExportMode(
 				this,
 				this.outputOptions,
-				this.unsetOptions,
 				this.facadeModule!.id,
 				this.inputOptions.onwarn
 			);

src/utils/error.ts

@@ -95,7 +95,6 @@ const ADDON_ERROR = 'ADDON_ERROR',
 	ONLY_INLINE_SOURCEMAPS = 'ONLY_INLINE_SOURCEMAPS',
 	PARSE_ERROR = 'PARSE_ERROR',
 	PLUGIN_ERROR = 'PLUGIN_ERROR',
-	PREFER_NAMED_EXPORTS = 'PREFER_NAMED_EXPORTS',
 	SHIMMED_EXPORT = 'SHIMMED_EXPORT',
 	SOURCEMAP_BROKEN = 'SOURCEMAP_BROKEN',
 	SOURCEMAP_ERROR = 'SOURCEMAP_ERROR',
@@ -710,16 +709,6 @@ export function errPluginError(
 	return error;
 }
 
-export function errPreferNamedExports(facadeModuleId: string): RollupLog {
-	const file = relativeId(facadeModuleId);
-	return {
-		code: PREFER_NAMED_EXPORTS,
-		id: facadeModuleId,
-		message: `Entry module "${file}" is implicitly using "default" export mode, which means for CommonJS output that its default export is assigned to "module.exports". For many tools, such CommonJS output will not be interchangeable with the original ES module. If this is intended, explicitly set "output.exports" to either "auto" or "default", otherwise you might want to consider changing the signature of "${file}" to use named exports only.`,
-		url: `https://rollupjs.org/guide/en/#outputexports`
-	};
-}
-
 export function errShimmedExport(id: string, binding: string): RollupLog {
 	return {
 		binding,

src/utils/getExportMode.ts

@@ -1,16 +1,10 @@
 import type Chunk from '../Chunk';
 import type { NormalizedOutputOptions, WarningHandler } from '../rollup/types';
-import {
-	errIncompatibleExportOptionValue,
-	errMixedExport,
-	error,
-	errPreferNamedExports
-} from './error';
+import { errIncompatibleExportOptionValue, errMixedExport, error } from './error';
 
 export default function getExportMode(
 	chunk: Chunk,
 	{ exports: exportMode, name, format }: NormalizedOutputOptions,
-	unsetOptions: ReadonlySet<string>,
 	facadeModuleId: string,
 	warn: WarningHandler
 ): 'default' | 'named' | 'none' {
@@ -28,9 +22,6 @@ export default function getExportMode(
 		if (exportKeys.length === 0) {
 			exportMode = 'none';
 		} else if (exportKeys.length === 1 && exportKeys[0] === 'default') {
-			if (format === 'cjs' && unsetOptions.has('exports')) {
-				warn(errPreferNamedExports(facadeModuleId));
-			}
 			exportMode = 'default';
 		} else {
 			if (format !== 'es' && format !== 'system' && exportKeys.includes('default')) {