Cache module info getters before output generation (#5438)

* Cache module info getters before output generation

* Update ExternalModule.ts

* Update Module.ts

* Update src/utils/getter.ts

Co-authored-by: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com>

* Remove safeguards as we are converting a hand-picked list

---------

Co-authored-by: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com>
Co-authored-by: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>

src/ExternalModule.ts

@@ -1,6 +1,7 @@
 import ExternalVariable from './ast/variables/ExternalVariable';
 import type { CustomPluginOptions, ModuleInfo, NormalizedInputOptions } from './rollup/types';
 import { EMPTY_ARRAY } from './utils/blank';
+import { cacheObjectGetters } from './utils/getter';
 import { makeLegal } from './utils/identifierHelpers';
 import { LOGLEVEL_WARN } from './utils/logging';
 import { logUnusedExternalImports } from './utils/logs';
@@ -59,6 +60,10 @@ export default class ExternalModule {
 		};
 	}
 
+	cacheInfoGetters(): void {
+		cacheObjectGetters(this.info, ['dynamicImporters', 'importers']);
+	}
+
 	getVariableForExportName(name: string): [variable: ExternalVariable] {
 		const declaration = this.declarations.get(name);
 		if (declaration) return [declaration];

src/Graph.ts

@@ -151,6 +151,7 @@ export default class Graph {
 			throw new Error('You must supply options.input to rollup');
 		}
 		for (const module of this.modulesById.values()) {
+			module.cacheInfoGetters();
 			if (module instanceof Module) {
 				this.modules.push(module);
 			} else {

src/Module.ts

@@ -55,6 +55,7 @@ import { decodedSourcemap, resetSourcemapCache } from './utils/decodedSourcemap'
 import { getId } from './utils/getId';
 import { getNewSet, getOrCreate } from './utils/getOrCreate';
 import { getOriginalLocation } from './utils/getOriginalLocation';
+import { cacheObjectGetters } from './utils/getter';
 import { makeLegal } from './utils/identifierHelpers';
 import { LOGLEVEL_WARN } from './utils/logging';
 import {
@@ -390,6 +391,22 @@ export default class Module {
 		this.ast!.bind();
 	}
 
+	cacheInfoGetters(): void {
+		cacheObjectGetters(this.info, [
+			'dynamicallyImportedIdResolutions',
+			'dynamicallyImportedIds',
+			'dynamicImporters',
+			'exportedBindings',
+			'exports',
+			'hasDefaultExport',
+			'implicitlyLoadedAfterOneOf',
+			'implicitlyLoadedBefore',
+			'importedIdResolutions',
+			'importedIds',
+			'importers'
+		]);
+	}
+
 	error(properties: RollupError, pos: number | undefined): never {
 		pos !== undefined && this.addLocationToLogProps(properties, pos);
 		return error(properties);

src/utils/getter.ts

@@ -0,0 +1,16 @@
+export function cacheObjectGetters<T, K extends PropertyKey = keyof T>(
+	object: T,
+	getterProperties: K[]
+) {
+	for (const property of getterProperties) {
+		const propertyGetter = Object.getOwnPropertyDescriptor(object, property)!.get!;
+		Object.defineProperty(object, property, {
+			get() {
+				const value = propertyGetter.call(object);
+				// This replaces the getter with a fixed value for subsequent calls
+				Object.defineProperty(object, property, { value });
+				return value;
+			}
+		});
+	}
+}