fix(semantic): reject await and yield in rest parameter defaults (#26359)

The parameter check only recognized `FormalParameter`, allowing `await` and `yield` in destructuring defaults inside rest parameters:

```js
async function f(...[x = await 0]) {}
function* g(...[x = yield 0]) {}
```

Include `FormalParameterRest` so both cases report the existing parameter diagnostic. The check still stops at nested functions, where `await` and `yield` can be valid.

crates/oxc_semantic/src/checker/javascript.rs

@@ -1296,9 +1296,16 @@ pub fn check_unary_expression(unary_expr: &UnaryExpression, ctx: &SemanticBuilde
 }
 
 fn is_in_formal_parameters(ctx: &SemanticBuilder<'_>) -> bool {
-    for node_kind in ctx.ancestry().ancestor_kinds() {
+    let mut ancestors = ctx.ancestry().ancestor_kinds().peekable();
+    while let Some(node_kind) = ancestors.next() {
         match node_kind {
             AstKind::FormalParameter(_) => return true,
+            // Only the rest binding belongs to the parameter; decorators use the surrounding context.
+            AstKind::BindingRestElement(_)
+                if matches!(ancestors.peek(), Some(AstKind::FormalParameterRest(_))) =>
+            {
+                return true;
+            }
             AstKind::Program(_) | AstKind::Function(_) | AstKind::ArrowFunctionExpression(_) => {
                 break;
             }

tasks/coverage/misc/fail/rest-parameter-default-await-yield.js

@@ -0,0 +1,2 @@
+async function f(...[x = await 0]) {}
+function* g(...[x = yield 0]) {}

tasks/coverage/misc/pass/rest-parameter-decorator-await.ts

@@ -0,0 +1,5 @@
+const p = Promise.resolve(() => {});
+class C {
+  async rest(@(await p) ...args: unknown[]) {}
+}
+export {};

tasks/coverage/misc/pass/rest-parameter-default-nested-functions.js

@@ -0,0 +1,2 @@
+async function f(...[x = async () => await 0]) {}
+function* g(...[x = function* () { yield 0; }]) {}

tasks/coverage/snapshots/codegen_misc.snap

@@ -1,3 +1,3 @@
 codegen_misc Summary:
-AST Parsed     : 81/81 (100.00%)
-Positive Passed: 81/81 (100.00%)
+AST Parsed     : 83/83 (100.00%)
+Positive Passed: 83/83 (100.00%)

tasks/coverage/snapshots/formatter_misc.snap

@@ -1,3 +1,3 @@
 formatter_misc Summary:
-AST Parsed     : 81/81 (100.00%)
-Positive Passed: 81/81 (100.00%)
+AST Parsed     : 83/83 (100.00%)
+Positive Passed: 83/83 (100.00%)

tasks/coverage/snapshots/lexer_misc.snap

@@ -1,6 +1,6 @@
 lexer_misc Summary:
-AST Parsed     : 250/250 (100.00%)
-Positive Passed: 248/250 (99.20%)
+AST Parsed     : 253/253 (100.00%)
+Positive Passed: 251/253 (99.21%)
 Tokens: tasks/coverage/misc/pass/oxc-2674.tsx
 
 Tokens: tasks/coverage/misc/pass/swc-7187.ts

tasks/coverage/snapshots/parser_misc.snap

@@ -1,7 +1,7 @@
 parser_misc Summary:
-AST Parsed     : 81/81 (100.00%)
-Positive Passed: 81/81 (100.00%)
-Negative Passed: 169/169 (100.00%)
+AST Parsed     : 83/83 (100.00%)
+Positive Passed: 83/83 (100.00%)
+Negative Passed: 170/170 (100.00%)
 
   × Cannot assign to 'arguments' in strict mode
    ╭─[misc/fail/arguments-eval-ambient.ts:2:13]
@@ -4292,6 +4292,22 @@ Negative Passed: 169/169 (100.00%)
    ╰────
   help: Expected an identifier, like `...rest`.
 
+  × await expression not allowed in formal parameter
+   ╭─[misc/fail/rest-parameter-default-await-yield.js:1:26]
+ 1 │ async function f(...[x = await 0]) {}
+   ·                          ───┬───
+   ·                             ╰── await expression not allowed in formal parameter
+ 2 │ function* g(...[x = yield 0]) {}
+   ╰────
+
+  × yield expression not allowed in formal parameter
+   ╭─[misc/fail/rest-parameter-default-await-yield.js:2:21]
+ 1 │ async function f(...[x = await 0]) {}
+ 2 │ function* g(...[x = yield 0]) {}
+   ·                     ───┬───
+   ·                        ╰── yield expression not allowed in formal parameter
+   ╰────
+
   × 'using' declarations are not allowed at the top level of a script
    ╭─[misc/fail/script-top-level-using.js:2:1]
  1 │ // 'using' is not allowed at top level in scripts

tasks/coverage/snapshots/semantic_misc.snap

@@ -1,6 +1,6 @@
 semantic_misc Summary:
-AST Parsed     : 81/81 (100.00%)
-Positive Passed: 77/81 (95.06%)
+AST Parsed     : 83/83 (100.00%)
+Positive Passed: 79/83 (95.18%)
 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     : 81/81 (100.00%)
-Positive Passed: 81/81 (100.00%)
+AST Parsed     : 83/83 (100.00%)
+Positive Passed: 83/83 (100.00%)