fix: Parser fails with C23 label syntax

[codomposer]

Summary

Fixes an issue where pycparser was reported to fail on C23-style empty labels such as a bare default: inside a switch.
The grammar already supports empty labels; this change adds a focused regression test to ensure that an empty default: is parsed correctly and remains supported.

Closes #576

Details

• Extend TestCParser_whole_code.test_switch_statement in tests/test_c_parser.py with a new case:

  int foo(void) {
      int x = 0;
      switch (x) {
      default:
      }
      return 0;
  }

Contribution by Gittensor, learn more at https://gittensor.io/

[eliben]

Such a test seems to already exist in test_case_empty_statement; is it different?

[codomposer]

Such a test seems to already exist in test_case_empty_statement; is it different?

oh, I missed it,
I just wanted to resolve the issue
I'd like to contribute to the repository, can you please assign another issue which hasn't been resolved yet?