chore(es/utils): Mark Symbol members as literal (#10400)

magic-akari · web-flow · commit 3935b6034068 · 2025-04-21T13:26:26.000-07:00
diff --git a/.changeset/kind-dolls-design.md b/.changeset/kind-dolls-design.md
@@ -0,0 +1,6 @@
+---
+swc_ecma_utils: patch
+swc_core: patch
+---
+
+chore(es/utils): Mark Symbol members as literal
diff --git a/crates/swc/tests/tsc-references/for-of27.1.normal.js b/crates/swc/tests/tsc-references/for-of27.1.normal.js
@@ -1,6 +1,4 @@
 //// [for-of27.ts]
-let prop;
 class StringIterator {
 }
-prop = Symbol.iterator;
 for (var v of new StringIterator){}
diff --git a/crates/swc/tests/tsc-references/parserES5SymbolProperty6.1.normal.js b/crates/swc/tests/tsc-references/parserES5SymbolProperty6.1.normal.js
@@ -1,9 +1,7 @@
 //// [parserES5SymbolProperty6.ts]
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
-var prop;
 var C = function C() {
     "use strict";
     _class_call_check(this, C);
-    this[prop] = "";
+    this[Symbol.toStringTag] = "";
 };
-prop = Symbol.toStringTag;
diff --git a/crates/swc/tests/tsc-references/parserSymbolProperty5.1.normal.js b/crates/swc/tests/tsc-references/parserSymbolProperty5.1.normal.js
@@ -1,5 +1,3 @@
 //// [parserSymbolProperty5.ts]
-let prop;
 class C {
 }
-prop = Symbol.toPrimitive;
diff --git a/crates/swc/tests/tsc-references/parserSymbolProperty6.1.normal.js b/crates/swc/tests/tsc-references/parserSymbolProperty6.1.normal.js
@@ -1,8 +1,6 @@
 //// [parserSymbolProperty6.ts]
-let prop;
 class C {
     constructor(){
-        this[prop] = "";
+        this[Symbol.toStringTag] = "";
     }
 }
-prop = Symbol.toStringTag;
diff --git a/crates/swc/tests/tsc-references/symbolDeclarationEmit1.1.normal.js b/crates/swc/tests/tsc-references/symbolDeclarationEmit1.1.normal.js
@@ -1,5 +1,3 @@
 //// [symbolDeclarationEmit1.ts]
-let prop;
 class C {
 }
-prop = Symbol.toPrimitive;
diff --git a/crates/swc/tests/tsc-references/symbolDeclarationEmit11.1.normal.js b/crates/swc/tests/tsc-references/symbolDeclarationEmit11.1.normal.js
@@ -1,12 +1,9 @@
 //// [symbolDeclarationEmit11.ts]
-let prop;
-let _Symbol_isConcatSpreadable = Symbol.isConcatSpreadable, _Symbol_toPrimitive = Symbol.toPrimitive, _Symbol_toPrimitive1 = Symbol.toPrimitive;
 class C {
-    static [_Symbol_isConcatSpreadable]() {}
-    static get [_Symbol_toPrimitive]() {
+    static [Symbol.isConcatSpreadable]() {}
+    static get [Symbol.toPrimitive]() {
         return "";
     }
-    static set [_Symbol_toPrimitive1](x) {}
+    static set [Symbol.toPrimitive](x) {}
 }
-prop = Symbol.iterator;
-C[prop] = 0;
+C[Symbol.iterator] = 0;
diff --git a/crates/swc/tests/tsc-references/symbolDeclarationEmit11.2.minified.js b/crates/swc/tests/tsc-references/symbolDeclarationEmit11.2.minified.js
@@ -1 +1,9 @@
 //// [symbolDeclarationEmit11.ts]
+class C {
+    static [Symbol.isConcatSpreadable]() {}
+    static get [Symbol.toPrimitive]() {
+        return "";
+    }
+    static set [Symbol.toPrimitive](x) {}
+}
+C[Symbol.iterator] = 0;
diff --git a/crates/swc/tests/tsc-references/symbolDeclarationEmit12.1.normal.js b/crates/swc/tests/tsc-references/symbolDeclarationEmit12.1.normal.js
@@ -1,18 +1,15 @@
 //// [symbolDeclarationEmit12.ts]
-let prop;
 (function(M) {
-    let _Symbol_toPrimitive = Symbol.toPrimitive, _Symbol_isConcatSpreadable = Symbol.isConcatSpreadable, _Symbol_toPrimitive1 = Symbol.toPrimitive, _Symbol_toPrimitive2 = Symbol.toPrimitive;
     class C {
-        [_Symbol_toPrimitive](x) {}
-        [_Symbol_isConcatSpreadable]() {
+        [Symbol.toPrimitive](x) {}
+        [Symbol.isConcatSpreadable]() {
             return undefined;
         }
-        get [_Symbol_toPrimitive1]() {
+        get [Symbol.toPrimitive]() {
             return undefined;
         }
-        set [_Symbol_toPrimitive2](x) {}
+        set [Symbol.toPrimitive](x) {}
     }
-    prop = Symbol.iterator;
     M.C = C;
 })(M || (M = {}));
 var M;
diff --git a/crates/swc/tests/tsc-references/symbolDeclarationEmit12.2.minified.js b/crates/swc/tests/tsc-references/symbolDeclarationEmit12.2.minified.js
@@ -1,9 +1,9 @@
 //// [symbolDeclarationEmit12.ts]
-var M, M1;
-let _Symbol_toPrimitive, _Symbol_isConcatSpreadable, _Symbol_toPrimitive1, _Symbol_toPrimitive2;
-M1 = M || (M = {}), _Symbol_toPrimitive = Symbol.toPrimitive, _Symbol_isConcatSpreadable = Symbol.isConcatSpreadable, _Symbol_toPrimitive1 = Symbol.toPrimitive, _Symbol_toPrimitive2 = Symbol.toPrimitive, M1.C = class {
-    [_Symbol_toPrimitive](x) {}
-    [_Symbol_isConcatSpreadable]() {}
-    get [_Symbol_toPrimitive1]() {}
-    set [_Symbol_toPrimitive2](x) {}
-};
+var M, M1 = M || (M = {});
+class C {
+    [Symbol.toPrimitive](x) {}
+    [Symbol.isConcatSpreadable]() {}
+    get [Symbol.toPrimitive]() {}
+    set [Symbol.toPrimitive](x) {}
+}
+M1.C = C;
diff --git a/crates/swc/tests/tsc-references/symbolDeclarationEmit2.1.normal.js b/crates/swc/tests/tsc-references/symbolDeclarationEmit2.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolDeclarationEmit2.ts]
-let prop;
 class C {
     constructor(){
-        this[prop] = "";
+        this[Symbol.toPrimitive] = "";
     }
 }
-prop = Symbol.toPrimitive;
diff --git a/crates/swc/tests/tsc-references/symbolProperty10.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty10.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolProperty10.ts]
-let prop;
 class C {
 }
-prop = Symbol.iterator;
 var i;
 i = new C;
 var c = i;
diff --git a/crates/swc/tests/tsc-references/symbolProperty12.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty12.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolProperty12.ts]
-let prop;
 class C {
 }
-prop = Symbol.iterator;
 var i;
 i = new C;
 var c = i;
diff --git a/crates/swc/tests/tsc-references/symbolProperty13.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty13.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolProperty13.ts]
-let prop;
 class C {
 }
-prop = Symbol.iterator;
 foo(new C);
 var i;
 bar(i);
diff --git a/crates/swc/tests/tsc-references/symbolProperty14.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty14.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolProperty14.ts]
-let prop;
 class C {
 }
-prop = Symbol.iterator;
 foo(new C);
 var i;
 bar(i);
diff --git a/crates/swc/tests/tsc-references/symbolProperty16.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty16.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolProperty16.ts]
-let prop;
 class C {
 }
-prop = Symbol.iterator;
 foo(new C);
 var i;
 bar(i);
diff --git a/crates/swc/tests/tsc-references/symbolProperty6.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty6.1.normal.js
@@ -1,16 +1,10 @@
 //// [symbolProperty6.ts]
-let prop, prop1;
-let _Symbol_toPrimitive = Symbol.toPrimitive, _Symbol_toStringTag = Symbol.toStringTag;
 class C {
-    [_Symbol_toPrimitive]() {}
-    get [_Symbol_toStringTag]() {
+    [Symbol.toPrimitive]() {}
+    get [Symbol.toStringTag]() {
         return 0;
     }
     constructor(){
-        this[prop] = 0;
+        this[Symbol.iterator] = 0;
     }
 }
-(()=>{
-    prop = Symbol.iterator;
-    prop1 = Symbol.unscopables;
-})();
diff --git a/crates/swc/tests/tsc-references/symbolProperty9.1.normal.js b/crates/swc/tests/tsc-references/symbolProperty9.1.normal.js
@@ -1,8 +1,6 @@
 //// [symbolProperty9.ts]
-let prop;
 class C {
 }
-prop = Symbol.iterator;
 var i;
 i = new C;
 var c = i;
diff --git a/crates/swc_ecma_utils/src/lib.rs b/crates/swc_ecma_utils/src/lib.rs
@@ -1078,7 +1078,11 @@ impl Visit for LiteralVisitor {
         self.is_lit = false;
     }
 
-    fn visit_member_expr(&mut self, _: &MemberExpr) {
+    fn visit_member_expr(&mut self, m: &MemberExpr) {
+        if m.obj.is_ident_ref_to("Symbol") {
+            return;
+        }
+
         self.is_lit = false;
     }
 

Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,4 @@`
`1`	`1`	`//// [for-of27.ts]`
`2`		`-let prop;`
`3`	`2`	`class StringIterator {`
`4`	`3`	`}`
`5`		`-prop = Symbol.iterator;`
`6`	`4`	`for (var v of new StringIterator){}`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,3 @@`
`1`	`1`	`//// [parserSymbolProperty5.ts]`
`2`		`-let prop;`
`3`	`2`	`class C {`
`4`	`3`	`}`
`5`		`-prop = Symbol.toPrimitive;`
Original file line number	Diff line number	Diff line change
`@@ -1,8 +1,6 @@`
`1`	`1`	`//// [parserSymbolProperty6.ts]`
`2`		`-let prop;`
`3`	`2`	`class C {`
`4`	`3`	`constructor(){`
`5`		`- this[prop] = "";`
	`4`	`+ this[Symbol.toStringTag] = "";`
`6`	`5`	`}`
`7`	`6`	`}`
`8`		`-prop = Symbol.toStringTag;`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,3 @@`
`1`	`1`	`//// [symbolDeclarationEmit1.ts]`
`2`		`-let prop;`
`3`	`2`	`class C {`
`4`	`3`	`}`
`5`		`-prop = Symbol.toPrimitive;`