Use entryFileNames for virtual files when preserveModules is set

src/Chunk.ts

@@ -434,12 +434,13 @@ export default class Chunk {
 		const id = this.orderedModules[0].id;
 		const sanitizedId = this.outputOptions.sanitizeFileName(id);
 		let path: string;
+		const pattern = unsetOptions.has('entryFileNames')
+			? '[name][assetExtname].js'
+			: options.entryFileNames;
+
 		if (isAbsolute(id)) {
-			const extension = extname(id);
-			const pattern = unsetOptions.has('entryFileNames')
-				? '[name][assetExtname].js'
-				: options.entryFileNames;
 			const currentDir = dirname(sanitizedId);
+			const extension = extname(id);
 			const fileName = renderNamePattern(
 				typeof pattern === 'function' ? pattern(this.getChunkInfo()) : pattern,
 				'output.entryFileNames',
@@ -459,7 +460,19 @@ export default class Chunk {
 				path = relative(preserveModulesRelativeDir, currentPath);
 			}
 		} else {
-			path = `_virtual/${basename(sanitizedId)}`;
+			const extension = extname(sanitizedId);
+			const fileName = renderNamePattern(
+				typeof pattern === 'function' ? pattern(this.getChunkInfo()) : pattern,
+				'output.entryFileNames',
+				{
+					assetExtname: () => (NON_ASSET_EXTENSIONS.includes(extension) ? '' : extension),
+					ext: () => extension.substr(1),
+					extname: () => extension,
+					format: () => options.format as string,
+					name: () => getAliasName(sanitizedId)
+				}
+			);
+			path = `_virtual/${fileName}`;
 		}
 		return makeUnique(normalize(path), existingNames);
 	}