Disallow async functions as loop bodies (#9314)

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

@@ -106,7 +106,12 @@ export default class StatementParser extends ExpressionParser {
         return this.parseForStatement(node);
       case tt._function:
         if (this.lookahead().type === tt.dot) break;
-        if (!declaration) this.unexpected();
+        if (!declaration) {
+          this.raise(
+            this.state.start,
+            "Function declaration not allowed in this context",
+          );
+        }
         return this.parseFunctionStatement(node);
 
       case tt._class:
@@ -189,7 +194,13 @@ export default class StatementParser extends ExpressionParser {
           const state = this.state.clone();
           this.next();
           if (this.match(tt._function) && !this.canInsertSemicolon()) {
-            this.expect(tt._function);
+            if (!declaration) {
+              this.raise(
+                this.state.lastTokStart,
+                "Function declaration not allowed in this context",
+              );
+            }
+            this.next();
             return this.parseFunction(node, true, false, true);
           } else {
             this.state = state;
@@ -210,7 +221,7 @@ export default class StatementParser extends ExpressionParser {
       expr.type === "Identifier" &&
       this.eat(tt.colon)
     ) {
-      return this.parseLabeledStatement(node, maybeName, expr);
+      return this.parseLabeledStatement(node, maybeName, expr, declaration);
     } else {
       return this.parseExpressionStatement(node, expr);
     }
@@ -649,6 +660,7 @@ export default class StatementParser extends ExpressionParser {
     node: N.LabeledStatement,
     maybeName: string,
     expr: N.Identifier,
+    declaration: boolean,
   ): N.LabeledStatement {
     for (const label of this.state.labels) {
       if (label.name === maybeName) {
@@ -676,7 +688,7 @@ export default class StatementParser extends ExpressionParser {
       kind: kind,
       statementStart: this.state.start,
     });
-    node.body = this.parseStatement(true);
+    node.body = this.parseStatement(declaration);
 
     if (
       node.body.type == "ClassDeclaration" ||

packages/babel-parser/test/fixtures/core/categorized/invalid-fn-decl-inside-loop/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Function declaration not allowed in this context (1:10)"
+}

packages/babel-parser/test/fixtures/core/categorized/invalid-fn-decl-labeled-inside-loop/input.js

@@ -0,0 +1 @@
+while (1) foo: bar: function foo(){}

packages/babel-parser/test/fixtures/core/categorized/invalid-fn-decl-labeled-inside-loop/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Function declaration not allowed in this context (1:20)"
+}

packages/babel-parser/test/fixtures/es2017/async-functions/invalid-inside-loop/input.js

@@ -0,0 +1 @@
+while (1) async function foo(){}

packages/babel-parser/test/fixtures/es2017/async-functions/invalid-inside-loop/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Function declaration not allowed in this context (1:10)"
+}

scripts/tests/test262/test262_whitelist.txt

@@ -1616,17 +1616,8 @@ language/statements/class/syntax/early-errors/class-definition-evaluation-block-
 language/statements/class/syntax/early-errors/class-definition-evaluation-scriptbody-duplicate-binding.js(default)
 language/statements/class/syntax/early-errors/class-definition-evaluation-scriptbody-duplicate-binding.js(strict mode)
 language/statements/const/redeclaration-error-from-within-strict-mode-function-const.js(default)
-language/statements/do-while/decl-async-fun.js(default)
-language/statements/do-while/decl-async-fun.js(strict mode)
-language/statements/do-while/decl-async-gen.js(default)
-language/statements/do-while/decl-async-gen.js(strict mode)
-language/statements/do-while/labelled-fn-stmt.js(default)
 language/statements/for-await-of/let-block-with-newline.js(default)
 language/statements/for-await-of/let-identifier-with-newline.js(default)
-language/statements/for-in/decl-async-fun.js(default)
-language/statements/for-in/decl-async-fun.js(strict mode)
-language/statements/for-in/decl-async-gen.js(default)
-language/statements/for-in/decl-async-gen.js(strict mode)
 language/statements/for-in/dstr/array-rest-before-elision.js(default)
 language/statements/for-in/dstr/array-rest-before-elision.js(strict mode)
 language/statements/for-in/dstr/array-rest-elision-invalid.js(default)
@@ -1642,16 +1633,8 @@ language/statements/for-in/head-let-bound-names-in-stmt.js(strict mode)
 language/statements/for-in/head-lhs-let.js(default)
 language/statements/for-in/head-var-bound-names-let.js(default)
 language/statements/for-in/identifier-let-allowed-as-lefthandside-expression-not-strict.js(default)
-language/statements/for-in/labelled-fn-stmt-const.js(default)
-language/statements/for-in/labelled-fn-stmt-let.js(default)
-language/statements/for-in/labelled-fn-stmt-lhs.js(default)
-language/statements/for-in/labelled-fn-stmt-var.js(default)
 language/statements/for-in/let-block-with-newline.js(default)
 language/statements/for-in/let-identifier-with-newline.js(default)
-language/statements/for-of/decl-async-fun.js(default)
-language/statements/for-of/decl-async-fun.js(strict mode)
-language/statements/for-of/decl-async-gen.js(default)
-language/statements/for-of/decl-async-gen.js(strict mode)
 language/statements/for-of/dstr/array-rest-before-elision.js(default)
 language/statements/for-of/dstr/array-rest-before-elision.js(strict mode)
 language/statements/for-of/dstr/array-rest-elision-invalid.js(default)
@@ -1672,45 +1655,15 @@ language/statements/for-of/head-let-bound-names-in-stmt.js(strict mode)
 language/statements/for-of/head-var-bound-names-let.js(default)
 language/statements/for-of/head-var-no-expr.js(default)
 language/statements/for-of/head-var-no-expr.js(strict mode)
-language/statements/for-of/labelled-fn-stmt-const.js(default)
-language/statements/for-of/labelled-fn-stmt-let.js(default)
-language/statements/for-of/labelled-fn-stmt-lhs.js(default)
-language/statements/for-of/labelled-fn-stmt-var.js(default)
 language/statements/for-of/let-block-with-newline.js(default)
 language/statements/for-of/let-identifier-with-newline.js(default)
-language/statements/for/decl-async-fun.js(default)
-language/statements/for/decl-async-fun.js(strict mode)
-language/statements/for/decl-async-gen.js(default)
-language/statements/for/decl-async-gen.js(strict mode)
 language/statements/for/head-let-bound-names-in-stmt.js(default)
 language/statements/for/head-let-bound-names-in-stmt.js(strict mode)
 language/statements/for/head-lhs-let.js(default)
-language/statements/for/labelled-fn-stmt-expr.js(default)
-language/statements/for/labelled-fn-stmt-let.js(default)
-language/statements/for/labelled-fn-stmt-var.js(default)
 language/statements/for/let-block-with-newline.js(default)
 language/statements/for/let-identifier-with-newline.js(default)
 language/statements/function/dflt-params-duplicates.js(default)
 language/statements/generators/dflt-params-duplicates.js(default)
-language/statements/if/if-async-fun-else-async-fun.js(default)
-language/statements/if/if-async-fun-else-async-fun.js(strict mode)
-language/statements/if/if-async-fun-else-stmt.js(default)
-language/statements/if/if-async-fun-else-stmt.js(strict mode)
-language/statements/if/if-async-fun-no-else.js(default)
-language/statements/if/if-async-fun-no-else.js(strict mode)
-language/statements/if/if-async-gen-else-async-gen.js(default)
-language/statements/if/if-async-gen-else-async-gen.js(strict mode)
-language/statements/if/if-async-gen-else-stmt.js(default)
-language/statements/if/if-async-gen-else-stmt.js(strict mode)
-language/statements/if/if-async-gen-no-else.js(default)
-language/statements/if/if-async-gen-no-else.js(strict mode)
-language/statements/if/if-stmt-else-async-fun.js(default)
-language/statements/if/if-stmt-else-async-fun.js(strict mode)
-language/statements/if/if-stmt-else-async-gen.js(default)
-language/statements/if/if-stmt-else-async-gen.js(strict mode)
-language/statements/if/labelled-fn-stmt-first.js(default)
-language/statements/if/labelled-fn-stmt-lone.js(default)
-language/statements/if/labelled-fn-stmt-second.js(default)
 language/statements/if/let-block-with-newline.js(default)
 language/statements/if/let-identifier-with-newline.js(default)
 language/statements/labeled/let-block-with-newline.js(default)
@@ -1850,15 +1803,7 @@ language/statements/try/early-catch-lex.js(default)
 language/statements/try/early-catch-lex.js(strict mode)
 language/statements/try/early-catch-var.js(default)
 language/statements/try/early-catch-var.js(strict mode)
-language/statements/while/decl-async-fun.js(default)
-language/statements/while/decl-async-fun.js(strict mode)
-language/statements/while/decl-async-gen.js(default)
-language/statements/while/decl-async-gen.js(strict mode)
-language/statements/while/labelled-fn-stmt.js(default)
 language/statements/while/let-block-with-newline.js(default)
 language/statements/while/let-identifier-with-newline.js(default)
-language/statements/with/decl-async-fun.js(default)
-language/statements/with/decl-async-gen.js(default)
-language/statements/with/labelled-fn-stmt.js(default)
 language/statements/with/let-block-with-newline.js(default)
 language/statements/with/let-identifier-with-newline.js(default)