fix(parser): disallow in expressions in using for-loop initializers (#26490)

Reject invalid initializers such as `for (using x = a in b;;);` by parsing `using` and `await using` declarations with `Context::In` disabled, matching ordinary for-loop declarations. Restore the outer context afterward so parenthesized `in` expressions and the remaining loop expressions keep their existing behavior.

crates/oxc_parser/src/js/statement.rs

@@ -536,7 +536,8 @@ impl<'a, C: Config> ParserImpl<'a, C> {
         parenthesis_opening_span: Span,
         r#await: bool,
     ) -> Statement<'a> {
-        let using_decl = self.parse_using_declaration(StatementContext::For);
+        let using_decl =
+            self.context_remove(Context::In, |p| p.parse_using_declaration(StatementContext::For));
 
         if matches!(self.cur_kind(), Kind::In) {
             if using_decl.kind.is_await() {

tasks/coverage/misc/fail/for-await-using-in-initializer.js

@@ -0,0 +1,3 @@
+async function f() {
+  for (await using x = a in b;;);
+}

tasks/coverage/misc/fail/for-using-in-initializer.js

@@ -0,0 +1 @@
+for (using x = a in b;;);

tasks/coverage/misc/pass/for-using-in-initializer.js

@@ -0,0 +1,11 @@
+for (using x = (a in b); a in b; a in b) {
+  a in b;
+}
+a in b;
+
+async function f() {
+  for (await using x = (a in b); a in b; a in b) {
+    a in b;
+  }
+  a in b;
+}

tasks/coverage/snapshots/codegen_misc.snap

@@ -1,3 +1,3 @@
 codegen_misc Summary:
-AST Parsed     : 96/96 (100.00%)
-Positive Passed: 96/96 (100.00%)
+AST Parsed     : 97/97 (100.00%)
+Positive Passed: 97/97 (100.00%)

tasks/coverage/snapshots/formatter_misc.snap

@@ -1,3 +1,3 @@
 formatter_misc Summary:
-AST Parsed     : 96/96 (100.00%)
-Positive Passed: 96/96 (100.00%)
+AST Parsed     : 97/97 (100.00%)
+Positive Passed: 97/97 (100.00%)

tasks/coverage/snapshots/lexer_misc.snap

@@ -1,3 +1,3 @@
 lexer_misc Summary:
-AST Parsed     : 294/294 (100.00%)
-Positive Passed: 294/294 (100.00%)
+AST Parsed     : 297/297 (100.00%)
+Positive Passed: 297/297 (100.00%)

tasks/coverage/snapshots/parser_misc.snap

@@ -1,7 +1,7 @@
 parser_misc Summary:
-AST Parsed     : 96/96 (100.00%)
-Positive Passed: 96/96 (100.00%)
-Negative Passed: 198/198 (100.00%)
+AST Parsed     : 97/97 (100.00%)
+Positive Passed: 97/97 (100.00%)
+Negative Passed: 200/200 (100.00%)
 
   × Cannot assign to 'arguments' in strict mode
    ╭─[misc/fail/arguments-eval-ambient.ts:2:13]
@@ -551,6 +551,40 @@ Negative Passed: 198/198 (100.00%)
    ·                ──
    ╰────
 
+  × The left-hand side of a for...in statement cannot be an await using declaration.
+   ╭─[misc/fail/for-await-using-in-initializer.js:2:8]
+ 1 │ async function f() {
+ 2 │   for (await using x = a in b;;);
+   ·        ─────────────────
+ 3 │ }
+   ╰────
+  help: Did you mean to use a for...of statement?
+
+  × Expected `)` but found `;`
+   ╭─[misc/fail/for-await-using-in-initializer.js:2:30]
+ 1 │ async function f() {
+ 2 │   for (await using x = a in b;;);
+   ·       ┬                      ┬
+   ·       │                      ╰── `)` expected
+   ·       ╰── Opened here
+ 3 │ }
+   ╰────
+
+  × The left-hand side of a for...in statement cannot be an using declaration.
+   ╭─[misc/fail/for-using-in-initializer.js:1:6]
+ 1 │ for (using x = a in b;;);
+   ·      ───────────
+   ╰────
+  help: Did you mean to use a for...of statement?
+
+  × Expected `)` but found `;`
+   ╭─[misc/fail/for-using-in-initializer.js:1:22]
+ 1 │ for (using x = a in b;;);
+   ·     ┬                ┬
+   ·     │                ╰── `)` expected
+   ·     ╰── Opened here
+   ╰────
+
   × A 'get' accessor must not have any formal parameters.
    ╭─[misc/fail/getter-rest-parameter.ts:1:16]
  1 │ class C { get x(...args) {} }

tasks/coverage/snapshots/semantic_misc.snap

@@ -1,6 +1,6 @@
 semantic_misc Summary:
-AST Parsed     : 96/96 (100.00%)
-Positive Passed: 92/96 (95.83%)
+AST Parsed     : 97/97 (100.00%)
+Positive Passed: 93/97 (95.88%)
 semantic Error: tasks/coverage/misc/pass/declare-let-private.ts
 Bindings mismatch:
 after transform: ScopeId(0): ["private"]

tasks/coverage/snapshots/transformer_misc.snap

@@ -1,3 +1,3 @@
 transformer_misc Summary:
-AST Parsed     : 96/96 (100.00%)
-Positive Passed: 96/96 (100.00%)
+AST Parsed     : 97/97 (100.00%)
+Positive Passed: 97/97 (100.00%)