feat(es/parser): Add an error for empty type args for generic (#11164)

**Related issue:**

 - Closes #11119

---------

Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>

Author: YashSuthar983

.changeset/afraid-coats-judge.md

@@ -0,0 +1,6 @@
+---
+swc_ecma_parser: patch
+swc_core: patch
+---
+
+Fixed Parser error for empty type args for generic

crates/swc_ecma_lexer/src/common/parser/typescript.rs

@@ -488,6 +488,12 @@ pub fn parse_ts_type_args<'a, P: Parser<'a>>(p: &mut P) -> PResult<Box<TsTypePar
     p.input_mut().set_expr_allowed(false);
     p.expect_without_advance(&P::Token::GREATER)?;
     let span = Span::new_with_checked(start, p.input().cur_span().hi);
+
+    // Report grammar error for empty type argument list like `I<>`.
+    if params.is_empty() {
+        p.emit_err(span, SyntaxError::EmptyTypeArgumentList);
+    }
+
     Ok(Box::new(TsTypeParamInstantiation { span, params }))
 }
 

crates/swc_ecma_lexer/src/error.rs

@@ -290,6 +290,7 @@ pub enum SyntaxError {
 
     ReservedTypeAssertion,
     ReservedArrowTypeParam,
+    EmptyTypeArgumentList,
 }
 
 impl SyntaxError {
@@ -744,6 +745,7 @@ impl SyntaxError {
                                                     .mts or .cts extension. Add a trailing comma, \
                                                     as in `<T,>() => ...`."
                 .into(),
+            SyntaxError::EmptyTypeArgumentList => "Type argument list cannot be empty.".into(),
             SyntaxError::InvalidAssignTarget => "Invalid assignment target".into(),
         }
     }

crates/swc_ecma_parser/tests/typescript-errors/type-args-empty/input.ts

@@ -0,0 +1,2 @@
+class I<T> { }
+var x: I<>;

crates/swc_ecma_parser/tests/typescript-errors/type-args-empty/input.ts.swc-stderr

@@ -0,0 +1,6 @@
+  x Type argument list cannot be empty.
+   ,-[$DIR/tests/typescript-errors/type-args-empty/input.ts:2:1]
+ 1 | class I<T> { }
+ 2 | var x: I<>;
+   :         ^^
+   `----