disallow of as a for-using-of binding

packages/babel-parser/src/parser/statement.ts

@@ -317,33 +317,8 @@ export default abstract class StatementParser extends ExpressionParser {
   startsUsingForOf(): boolean {
     const lookahead = this.lookahead();
     if (lookahead.type === tt._of && lookahead.end - lookahead.start === 2) {
-      // using of ...
-      const originalState = this.state;
-      // @ts-expect-error: Second lookahead
-      this.state = lookahead;
-      const lookaheadAhead = this.lookahead();
-      this.state = originalState;
-      if (
-        lookaheadAhead.type === tt._of &&
-        lookaheadAhead.end - lookaheadAhead.start === 2
-      ) {
-        // using of of ...
-        const nextNextNextTokenStart = this.nextTokenStartSince(
-          lookaheadAhead.end,
-        );
-        if (
-          this.input.charCodeAt(nextNextNextTokenStart) ===
-          charCodes.rightParenthesis
-        ) {
-          // using of of)
-          return false;
-        } else {
-          this.expectPlugin("explicitResourceManagement");
-          return true;
-        }
-      } else {
-        return false;
-      }
+      // `using of` must start a for-lhs-of statement
+      return false;
     } else {
       this.expectPlugin("explicitResourceManagement");
       return true;

packages/babel-parser/test/fixtures/experimental/explicit-resource-management/invalid-for-await-using-binding-of-of/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "throws": "Unexpected token, expected \")\" (1:23)"
+}

packages/babel-parser/test/fixtures/experimental/explicit-resource-management/invalid-for-using-binding-of-of/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Unexpected token, expected \")\" (1:17)"
+}

packages/babel-parser/test/fixtures/experimental/explicit-resource-management/valid-for-await-using-binding-escaped-of-of/input.mjs

@@ -0,0 +1 @@
+for await (using \u006ff of of);

packages/babel-parser/test/fixtures/experimental/explicit-resource-management/valid-for-await-using-binding-escaped-of-of/output.json

@@ -0,0 +1,44 @@
+{
+  "type": "File",
+  "start":0,"end":32,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":32,"index":32}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":32,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":32,"index":32}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ForOfStatement",
+        "start":0,"end":32,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":32,"index":32}},
+        "await": true,
+        "left": {
+          "type": "VariableDeclaration",
+          "start":11,"end":24,"loc":{"start":{"line":1,"column":11,"index":11},"end":{"line":1,"column":24,"index":24}},
+          "declarations": [
+            {
+              "type": "VariableDeclarator",
+              "start":17,"end":24,"loc":{"start":{"line":1,"column":17,"index":17},"end":{"line":1,"column":24,"index":24}},
+              "id": {
+                "type": "Identifier",
+                "start":17,"end":24,"loc":{"start":{"line":1,"column":17,"index":17},"end":{"line":1,"column":24,"index":24},"identifierName":"of"},
+                "name": "of"
+              },
+              "init": null
+            }
+          ],
+          "kind": "using"
+        },
+        "right": {
+          "type": "Identifier",
+          "start":28,"end":30,"loc":{"start":{"line":1,"column":28,"index":28},"end":{"line":1,"column":30,"index":30},"identifierName":"of"},
+          "name": "of"
+        },
+        "body": {
+          "type": "EmptyStatement",
+          "start":31,"end":32,"loc":{"start":{"line":1,"column":31,"index":31},"end":{"line":1,"column":32,"index":32}}
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/experimental/explicit-resource-management/valid-for-using-binding-escaped-of-of/input.js

@@ -0,0 +1 @@
+for (using o\u0066 of of);

packages/babel-parser/test/fixtures/experimental/explicit-resource-management/valid-for-using-binding-escaped-of-of/output.json

@@ -0,0 +1,44 @@
+{
+  "type": "File",
+  "start":0,"end":26,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":26,"index":26}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":26,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":26,"index":26}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ForOfStatement",
+        "start":0,"end":26,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":26,"index":26}},
+        "await": false,
+        "left": {
+          "type": "VariableDeclaration",
+          "start":5,"end":18,"loc":{"start":{"line":1,"column":5,"index":5},"end":{"line":1,"column":18,"index":18}},
+          "declarations": [
+            {
+              "type": "VariableDeclarator",
+              "start":11,"end":18,"loc":{"start":{"line":1,"column":11,"index":11},"end":{"line":1,"column":18,"index":18}},
+              "id": {
+                "type": "Identifier",
+                "start":11,"end":18,"loc":{"start":{"line":1,"column":11,"index":11},"end":{"line":1,"column":18,"index":18},"identifierName":"of"},
+                "name": "of"
+              },
+              "init": null
+            }
+          ],
+          "kind": "using"
+        },
+        "right": {
+          "type": "Identifier",
+          "start":22,"end":24,"loc":{"start":{"line":1,"column":22,"index":22},"end":{"line":1,"column":24,"index":24},"identifierName":"of"},
+          "name": "of"
+        },
+        "body": {
+          "type": "EmptyStatement",
+          "start":25,"end":26,"loc":{"start":{"line":1,"column":25,"index":25},"end":{"line":1,"column":26,"index":26}}
+        }
+      }
+    ],
+    "directives": []
+  }
+}