From edfeedd8b68f8af56d8e8a29d303c87d24152356 Mon Sep 17 00:00:00 2001
From: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>
Date: Sun, 9 Jan 2022 06:47:17 +0100
Subject: [PATCH] Implement shouldTransformCachedModule

---
 src/ModuleLoader.ts       | 12 +++++++++-
 src/rollup/types.d.ts     | 19 +++++++++++++--
 src/utils/PluginDriver.ts |  1 +
 test/incremental/index.js | 50 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 79 insertions(+), 3 deletions(-)

diff --git a/src/ModuleLoader.ts b/src/ModuleLoader.ts
index ede3546b14f..648d9aba78b 100644
--- a/src/ModuleLoader.ts
+++ b/src/ModuleLoader.ts
@@ -274,7 +274,17 @@ export class ModuleLoader {
 		if (
 			cachedModule &&
 			!cachedModule.customTransformCache &&
-			cachedModule.originalCode === sourceDescription.code
+			cachedModule.originalCode === sourceDescription.code &&
+			!(await this.pluginDriver.hookFirst('shouldTransformCachedModule', [
+				{
+					ast: cachedModule.ast,
+					code: cachedModule.code,
+					id: cachedModule.id,
+					meta: cachedModule.meta,
+					moduleSideEffects: cachedModule.moduleSideEffects,
+					syntheticNamedExports: cachedModule.syntheticNamedExports
+				}
+			]))
 		) {
 			if (cachedModule.transformFiles) {
 				for (const emittedFile of cachedModule.transformFiles)
diff --git a/src/rollup/types.d.ts b/src/rollup/types.d.ts
index 1197dc41e8a..55c3c0b1f87 100644
--- a/src/rollup/types.d.ts
+++ b/src/rollup/types.d.ts
@@ -113,7 +113,7 @@ export interface TransformModuleJSON extends Partial<PartialNull<ModuleOptions>>
 	transformDependencies: string[];
 }
 
-export interface ModuleJSON extends TransformModuleJSON {
+export interface ModuleJSON extends ModuleOptions, TransformModuleJSON {
 	ast: AcornNode;
 	dependencies: string[];
 	id: string;
@@ -242,6 +242,18 @@ export type ResolveIdHook = (
 	options: { custom?: CustomPluginOptions; isEntry: boolean }
 ) => Promise<ResolveIdResult> | ResolveIdResult;
 
+export type ShouldTransformCachedModuleHook = (
+	this: PluginContext,
+	options: {
+		ast: AcornNode;
+		code: string;
+		id: string;
+		meta: CustomPluginOptions;
+		moduleSideEffects: boolean | 'no-treeshake';
+		syntheticNamedExports: boolean | string;
+	}
+) => Promise<boolean> | boolean;
+
 export type IsExternal = (
 	source: string,
 	importer: string | undefined,
@@ -367,6 +379,7 @@ export interface PluginHooks extends OutputPluginHooks {
 	) => Promise<InputOptions | null | undefined> | InputOptions | null | undefined;
 	resolveDynamicImport: ResolveDynamicImportHook;
 	resolveId: ResolveIdHook;
+	shouldTransformCachedModule: ShouldTransformCachedModuleHook;
 	transform: TransformHook;
 	watchChange: WatchChangeHook;
 }
@@ -419,6 +432,7 @@ export type AsyncPluginHooks =
 	| 'renderStart'
 	| 'resolveDynamicImport'
 	| 'resolveId'
+	| 'shouldTransformCachedModule'
 	| 'transform'
 	| 'writeBundle'
 	| 'closeBundle';
@@ -434,7 +448,8 @@ export type FirstPluginHooks =
 	| 'resolveDynamicImport'
 	| 'resolveFileUrl'
 	| 'resolveId'
-	| 'resolveImportMeta';
+	| 'resolveImportMeta'
+	| 'shouldTransformCachedModule';
 
 export type SequentialPluginHooks =
 	| 'augmentChunkHash'
diff --git a/src/utils/PluginDriver.ts b/src/utils/PluginDriver.ts
index 1a77fe57851..b96b54880b1 100644
--- a/src/utils/PluginDriver.ts
+++ b/src/utils/PluginDriver.ts
@@ -55,6 +55,7 @@ const inputHookNames: {
 	options: 1,
 	resolveDynamicImport: 1,
 	resolveId: 1,
+	shouldTransformCachedModule: 1,
 	transform: 1,
 	watchChange: 1
 };
diff --git a/test/incremental/index.js b/test/incremental/index.js
index 1595ca248d7..794fcc6a17f 100644
--- a/test/incremental/index.js
+++ b/test/incremental/index.js
@@ -336,4 +336,54 @@ describe('incremental', () => {
 		assert.strictEqual(transformCalls, 2);
 		assert.strictEqual(moduleParsedCalls, 4); // should not be cached
 	});
+
+	it('runs shouldTransformCachedModule when using a cached module', async () => {
+		let shouldTransformCachedModuleCalls = 0;
+
+		const transformPlugin = {
+			async shouldTransformCachedModule({ ast, id, meta, ...other }) {
+				shouldTransformCachedModuleCalls++;
+				assert.strictEqual(ast.type, 'Program');
+				assert.deepStrictEqual(other, {
+					code: modules[id],
+					moduleSideEffects: true,
+					syntheticNamedExports: false
+				});
+				switch (id) {
+					case 'foo':
+						assert.deepStrictEqual(meta, { transform: { calls: 1, id } });
+						// we return promises to ensure they are awaited
+						return Promise.resolve(false);
+					case 'entry':
+						assert.deepStrictEqual(meta, { transform: { calls: 0, id } });
+						return Promise.resolve(true);
+					default:
+						throw new Error(`Unexpected id ${id}.`);
+				}
+			},
+			transform: (code, id) => {
+				return { meta: { transform: { calls: transformCalls, id } } };
+			}
+		};
+		const cache = await rollup.rollup({
+			input: 'entry',
+			plugins: [transformPlugin, plugin]
+		});
+		assert.strictEqual(shouldTransformCachedModuleCalls, 0);
+		assert.strictEqual(transformCalls, 2);
+
+		const {
+			cache: { modules: cachedModules }
+		} = await rollup.rollup({
+			input: 'entry',
+			plugins: [transformPlugin, plugin],
+			cache
+		});
+		assert.strictEqual(shouldTransformCachedModuleCalls, 2);
+		assert.strictEqual(transformCalls, 3);
+		assert.strictEqual(cachedModules[0].id, 'foo');
+		assert.deepStrictEqual(cachedModules[0].meta, { transform: { calls: 1, id: 'foo' } });
+		assert.strictEqual(cachedModules[1].id, 'entry');
+		assert.deepStrictEqual(cachedModules[1].meta, { transform: { calls: 2, id: 'entry' } });
+	});
 });