fix(parser): preserve in-context after TypeScript type arguments (#28300)

Type arguments followed by `in` must preserve the surrounding grammar
context. Accept the binary operator in expressions while leaving it
available as the separator in `for-in` heads.

AI-assisted implementation.

crates/oxc_parser/src/ts/types.rs

@@ -1610,7 +1610,7 @@ impl<'a, C: Config> ParserImpl<'a, C> {
     }
 
     fn is_binary_operator(&self) -> bool {
-        if self.ctx.has_in() && self.at(Kind::In) {
+        if !self.ctx.has_in() && self.at(Kind::In) {
             return false;
         }
         self.cur_kind().is_binary_operator()
@@ -1624,7 +1624,7 @@ impl<'a, C: Config> ParserImpl<'a, C> {
             kind if kind.is_unary_operator() => true,
             kind if kind.is_update_operator() => true,
             Kind::LAngle | Kind::Await | Kind::Yield | Kind::Private | Kind::At => true,
-            kind if kind.is_binary_operator() => true,
+            _ if self.is_binary_operator() => true,
             kind => kind.is_ts_identifier(self.ctx.has_yield(), self.ctx.has_await()),
         }
     }

tasks/coverage/misc/pass/instantiation-before-for-in.cts

@@ -0,0 +1,5 @@
+const factory = null as unknown as string & { <T>(): T };
+const object = {};
+
+// Keep the instantiation before the for-in delimiter in this non-strict CommonJS file.
+for (var key = factory<number> in object) {}

tasks/coverage/misc/pass/instantiation-in-operator.ts

@@ -0,0 +1,10 @@
+const factory = null as unknown as string & { <T>(): T };
+const object = {};
+type Box<T> = { value: T };
+
+const direct = factory<number> in object;
+const nested = factory<Box<number>> in object;
+
+if (factory<string> in object) {}
+for (; factory<number> in object; ) {}
+for (let present = (factory<boolean> in object); present; ) {}

tasks/coverage/snapshots/codegen_misc.snap

@@ -1,3 +1,3 @@
 codegen_misc Summary:
-AST Parsed     : 125/125 (100.00%)
-Positive Passed: 125/125 (100.00%)
+AST Parsed     : 127/127 (100.00%)
+Positive Passed: 127/127 (100.00%)

tasks/coverage/snapshots/formatter_misc.snap

@@ -1,3 +1,3 @@
 formatter_misc Summary:
-AST Parsed     : 125/125 (100.00%)
-Positive Passed: 125/125 (100.00%)
+AST Parsed     : 127/127 (100.00%)
+Positive Passed: 127/127 (100.00%)

tasks/coverage/snapshots/lexer_misc.snap

@@ -1,3 +1,3 @@
 lexer_misc Summary:
-AST Parsed     : 388/388 (100.00%)
-Positive Passed: 388/388 (100.00%)
+AST Parsed     : 390/390 (100.00%)
+Positive Passed: 390/390 (100.00%)

tasks/coverage/snapshots/parser_misc.snap

@@ -1,6 +1,6 @@
 parser_misc Summary:
-AST Parsed     : 125/125 (100.00%)
-Positive Passed: 125/125 (100.00%)
+AST Parsed     : 127/127 (100.00%)
+Positive Passed: 127/127 (100.00%)
 Negative Passed: 265/265 (100.00%)
 
   × TS(1275): 'accessor' modifier can only appear on a property declaration.

tasks/coverage/snapshots/semantic_misc.snap

@@ -1,6 +1,6 @@
 semantic_misc Summary:
-AST Parsed     : 125/125 (100.00%)
-Positive Passed: 119/125 (95.20%)
+AST Parsed     : 127/127 (100.00%)
+Positive Passed: 121/127 (95.28%)
 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     : 125/125 (100.00%)
-Positive Passed: 125/125 (100.00%)
+AST Parsed     : 127/127 (100.00%)
+Positive Passed: 127/127 (100.00%)