Clearer empty chunk warning

cli/run/batchWarnings.ts

@@ -110,10 +110,6 @@ const immediateHandlers: {
 		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`
 		);
-	},
-
-	EMPTY_BUNDLE: () => {
-		title(`Generated an empty bundle`);
 	}
 };
 
@@ -270,6 +266,20 @@ const deferredHandlers: {
 			});
 		},
 		priority: 1
+	},
+
+	EMPTY_BUNDLE: {
+		fn: warnings => {
+			title(
+				`Generated${warnings.length === 1 ? ' an' : ''} empty ${
+					warnings.length > 1 ? 'chunks' : 'chunk'
+				}`
+			);
+			warnings.forEach(warning => {
+				stderr(warning.chunkName as string);
+			});
+		},
+		priority: 1
 	}
 };
 

src/Chunk.ts

@@ -620,9 +620,11 @@ export default class Chunk {
 		this.renderedHash = undefined as any;
 
 		if (this.getExportNames().length === 0 && this.getImportIds().length === 0 && this.isEmpty) {
+			const chunkName = this.getChunkName();
 			this.graph.warn({
+				chunkName,
 				code: 'EMPTY_BUNDLE',
-				message: 'Generated an empty bundle'
+				message: `Generated an empty chunk: "${chunkName}"`
 			});
 		}
 

src/rollup/types.d.ts

@@ -10,6 +10,7 @@ export interface RollupError extends RollupLogProps {
 }
 
 export interface RollupWarning extends RollupLogProps {
+	chunkName?: string;
 	exporter?: string;
 	exportName?: string;
 	guess?: string;

test/function/samples/assign-namespace-to-var/_config.js

@@ -2,8 +2,9 @@ module.exports = {
 	description: 'allows a namespace to be assigned to a variable',
 	warnings: [
 		{
+			chunkName: 'main',
 			code: 'EMPTY_BUNDLE',
-			message: 'Generated an empty bundle'
+			message: 'Generated an empty chunk: "main"'
 		}
 	]
 };

test/function/samples/can-import-self-treeshake/_config.js

@@ -7,8 +7,9 @@ module.exports = {
 			message: 'Circular dependency: lib.js -> lib.js'
 		},
 		{
+			chunkName: 'main',
 			code: 'EMPTY_BUNDLE',
-			message: `Generated an empty bundle`
+			message: `Generated an empty chunk: "main"`
 		}
 	]
 };

test/function/samples/module-tree/_config.js

@@ -34,8 +34,9 @@ module.exports = {
 	},
 	warnings: [
 		{
+			chunkName: 'main',
 			code: 'EMPTY_BUNDLE',
-			message: 'Generated an empty bundle'
+			message: 'Generated an empty chunk: "main"'
 		}
 	]
 };

test/function/samples/vars-with-init-in-dead-branch/_config.js

@@ -2,8 +2,9 @@ module.exports = {
 	description: 'handles vars with init in dead branch (#1198)',
 	warnings: [
 		{
+			chunkName: 'main',
 			code: 'EMPTY_BUNDLE',
-			message: 'Generated an empty bundle'
+			message: 'Generated an empty chunk: "main"'
 		}
 	]
 };

test/function/samples/warn-on-empty-bundle/_config.js

@@ -2,8 +2,9 @@ module.exports = {
 	description: 'warns if empty bundle is generated  (#444)',
 	warnings: [
 		{
+			chunkName: 'main',
 			code: 'EMPTY_BUNDLE',
-			message: 'Generated an empty bundle'
+			message: 'Generated an empty chunk: "main"'
 		}
 	]
 };

test/function/samples/warnings-to-string/_config.js

@@ -13,7 +13,7 @@ module.exports = {
 	warnings(warnings) {
 		assert.deepStrictEqual(warnings.map(String), [
 			'(test-plugin plugin) main.js (1:6) This might be removed',
-			'Generated an empty bundle'
+			'Generated an empty chunk: "main"'
 		]);
 	}
 };