From 439591ad5ffc716b31b7113cbbf177ab3ef7521d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Sun, 1 Sep 2019 09:04:50 +0200
Subject: [PATCH] Add support for entryFileNames pattern used in combination
 with preserveModules option

---
 src/Chunk.ts                | 26 ++++++++++++++++++--------
 src/utils/assignChunkIds.ts |  2 +-
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/src/Chunk.ts b/src/Chunk.ts
index 7b80a01ffb0..ed864b92c8e 100644
--- a/src/Chunk.ts
+++ b/src/Chunk.ts
@@ -277,17 +277,27 @@ export default class Chunk {
 
 	generateIdPreserveModules(
 		preserveModulesRelativeDir: string,
+		options: OutputOptions,
 		existingNames: Record<string, any>
 	): string {
 		const sanitizedId = sanitizeFileName(this.orderedModules[0].id);
-		return makeUnique(
-			normalize(
-				isAbsolute(this.orderedModules[0].id)
-					? relative(preserveModulesRelativeDir, sanitizedId)
-					: '_virtual/' + basename(sanitizedId)
-			),
-			existingNames
-		);
+
+		let path: string;
+		if (isAbsolute(this.orderedModules[0].id)) {
+			const name = renderNamePattern(
+				options.entryFileNames || '[name].js',
+				'output.entryFileNames',
+				{
+					format: () => (options.format === 'es' ? 'esm' : (options.format as string)),
+					name: () => this.getChunkName()
+				}
+			);
+
+			path = relative(preserveModulesRelativeDir, `${dirname(sanitizedId)}/${name}`);
+		} else {
+			path = `_virtual/${basename(sanitizedId)}`;
+		}
+		return makeUnique(normalize(path), existingNames);
 	}
 
 	generateInternalExports(options: OutputOptions) {
diff --git a/src/utils/assignChunkIds.ts b/src/utils/assignChunkIds.ts
index 5ed2d58faaa..ae479ae4684 100644
--- a/src/utils/assignChunkIds.ts
+++ b/src/utils/assignChunkIds.ts
@@ -27,7 +27,7 @@ export function assignChunkIds(
 		if (outputOptions.file) {
 			chunk.id = basename(outputOptions.file);
 		} else if (inputOptions.preserveModules) {
-			chunk.id = chunk.generateIdPreserveModules(inputBase, bundle);
+			chunk.id = chunk.generateIdPreserveModules(inputBase, outputOptions, bundle);
 		} else {
 			chunk.id = chunk.generateId(addons, outputOptions, bundle, true);
 		}