Only consider Object.freeze a side effect if the argument is used (#4720

)

src/ast/nodes/shared/knownGlobals.ts

@@ -214,6 +214,7 @@ const knownGlobals: GlobalDescription = {
 		// deoptimizes everything anyway
 		defineProperty: MUTATES_ARG_WITHOUT_ACCESSOR,
 		defineProperties: MUTATES_ARG_WITHOUT_ACCESSOR,
+		freeze: MUTATES_ARG_WITHOUT_ACCESSOR,
 		getOwnPropertyDescriptor: PF,
 		getOwnPropertyNames: PF,
 		getOwnPropertySymbols: PF,

test/form/samples/big-int/_config.js

@@ -1,4 +1,3 @@
 module.exports = {
-	description: 'supports bigint via acorn plugin',
-	options: {}
+	description: 'supports bigint via acorn plugin'
 };

test/form/samples/object-freeze-effects/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'Only treats Object.freeze as a side effect if the argument is used'
+};

test/form/samples/object-freeze-effects/_expected.js

@@ -0,0 +1,6 @@
+const b = Object.freeze({ foo: 'bar' });
+console.log(b);
+
+const c = { foo: 'bar' };
+Object.freeze(c); // retained
+console.log(c);

test/form/samples/object-freeze-effects/main.js

@@ -0,0 +1,11 @@
+Object.freeze({ foo: 'bar' }); // removed
+
+const a = { foo: 'bar' }; // removed
+Object.freeze(a); // removed
+
+const b = Object.freeze({ foo: 'bar' });
+console.log(b);
+
+const c = { foo: 'bar' };
+Object.freeze(c); // retained
+console.log(c);