Cache module info getters before output generation

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';
@@ -30,6 +31,7 @@ export default class ExternalModule {
 		this.suggestedVariableName = makeLegal(id.split(/[/\\]/).pop()!);
 
 		const { importers, dynamicImporters } = this;
+		// NOTE: any getter props should also be defined in cacheInfoGetters
 		this.info = {
 			ast: null,
 			attributes,
@@ -59,6 +61,10 @@ 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 {
@@ -293,6 +294,7 @@ export default class Module {
 			sourcesWithAttributes
 		} = this;
 
+		// NOTE: any getter props should also be defined in cacheInfoGetters
 		this.info = {
 			ast: null,
 			attributes,
@@ -390,6 +392,23 @@ export default class Module {
 		this.ast!.bind();
 	}
 
+	cacheInfoGetters(): void {
+		cacheObjectGetters(this.info, [
+			'dynamicallyImportedIdResolutions',
+			'dynamicallyImportedIds',
+			'dynamicImporters',
+			'exportedBindings',
+			'exports',
+			'hasDefaultExport',
+			'implicitlyLoadedAfterOneOf',
+			'implicitlyLoadedBefore',
+			'importedIdResolutions',
+			'importedIds',
+			'importers',
+			'isIncluded'
+		]);
+	}
+
 	error(properties: RollupError, pos: number | undefined): never {
 		pos !== undefined && this.addLocationToLogProps(properties, pos);
 		return error(properties);

src/utils/getter.ts

@@ -0,0 +1,19 @@
+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;
+		if (propertyGetter) {
+			let cached: unknown;
+			Object.defineProperty(object, property, {
+				get: () => {
+					if (cached === undefined) {
+						cached = propertyGetter.call(object);
+					}
+					return cached;
+				}
+			});
+		}
+	}
+}