feat: mark Set, Map, WeakSet and WeakMap with array arguments as pure (…

…#5005) Co-authored-by: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com>
rollup · May 22, 2023 · 5ea3655 · 5ea3655
1 parent 6d78dea
commit 5ea3655
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Showing 4 changed files with 52 additions and 4 deletions.
diff --git a/src/ast/nodes/shared/knownGlobals.ts b/src/ast/nodes/shared/knownGlobals.ts
@@ -10,6 +10,7 @@ import {
 	UNKNOWN_NON_ACCESSOR_PATH,
 	UNKNOWN_PATH
 } from '../../utils/PathTracker';
+import ArrayExpression from '../ArrayExpression';
 import type { LiteralValueOrUnknown } from './Expression';
 import { UnknownTruthyValue } from './Expression';
 
@@ -43,6 +44,14 @@ const IMPURE: ValueDescription = {
 	hasEffectsWhenCalled: returnTrue
 };
 
+const PURE_WITH_ARRAY: ValueDescription = {
+	deoptimizeArgumentsOnCall: doNothing,
+	getLiteralValue: getTruthyLiteralValue,
+	hasEffectsWhenCalled({ args }) {
+		return args.length > 1 && !(args[1] instanceof ArrayExpression);
+	}
+};
+
 // We use shortened variables to reduce file size here
 /* OBJECT */
 const O: GlobalDescription = {
@@ -91,6 +100,12 @@ const PC: GlobalDescription = {
 	prototype: O
 };
 
+const PC_WITH_ARRAY = {
+	__proto__: null,
+	[ValueProperties]: PURE_WITH_ARRAY,
+	prototype: O
+};
+
 const ARRAY_TYPE: GlobalDescription = {
 	__proto__: null,
 	[ValueProperties]: PURE,
@@ -164,7 +179,7 @@ const knownGlobals: GlobalDescription = {
 	isNaN: PF,
 	isPrototypeOf: O,
 	JSON: O,
-	Map: C,
+	Map: PC_WITH_ARRAY,
 	Math: {
 		__proto__: null,
 		[ValueProperties]: IMPURE,
@@ -260,7 +275,7 @@ const knownGlobals: GlobalDescription = {
 	ReferenceError: PC,
 	Reflect: O,
 	RegExp: PC,
-	Set: C,
+	Set: PC_WITH_ARRAY,
 	SharedArrayBuffer: C,
 	String: {
 		__proto__: null,
@@ -300,8 +315,8 @@ const knownGlobals: GlobalDescription = {
 	unescape: PF,
 	URIError: PC,
 	valueOf: O,
-	WeakMap: C,
-	WeakSet: C,
+	WeakMap: PC_WITH_ARRAY,
+	WeakSet: PC_WITH_ARRAY,
 
 	// Additional globals shared by Node and Browser that are not strictly part of the language
 	clearInterval: C,

diff --git a/test/form/samples/tree-shake-global-variables/_config.js b/test/form/samples/tree-shake-global-variables/_config.js
@@ -0,0 +1,3 @@
+module.exports = defineTest({
+	description: 'retain Set, Map, WeakSet and WeakMap which called with array arguments'
+});
diff --git a/test/form/samples/tree-shake-global-variables/_expected.js b/test/form/samples/tree-shake-global-variables/_expected.js
@@ -0,0 +1,7 @@
+new Set([f()]); //retained
+
+new WeakSet([f()]); //retained
+
+new Map([['a', f()]]); //retained
+
+new WeakMap([[f(), 'a']]); //retained
diff --git a/test/form/samples/tree-shake-global-variables/main.js b/test/form/samples/tree-shake-global-variables/main.js
@@ -0,0 +1,23 @@
+new Set([f()]); //retained
+
+new Set(['a']);
+
+new Set();
+
+new WeakSet([f()]); //retained
+
+new WeakSet([{}]);
+
+new WeakSet();
+
+new Map([['a', f()]]); //retained
+
+new Map([['a', 'a']]);
+
+new Map();
+
+new WeakMap([[f(), 'a']]); //retained
+
+new WeakMap([[{}, 'a']]);
+
+new WeakMap();