[Bug c++/96552] New: GCC accepts "alignas(auto)" in function parameter list

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96552

            Bug ID: 96552
           Summary: GCC accepts "alignas(auto)" in function parameter list
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

Hi, all.

Following code is invalid I think, the "alignas" shouldn't be in function
parameter. I guess GCC only finds a "auto" in function parameter list rather
than "alignas(auto)", also "alignas(auto)" itself is invalid.

Code:
class Test{
    Test &operator || (alignas(auto) int);
};

While Clang says "error: 'auto' not allowed here".

Every version from GCC-6.1 upwards behaves the same.

Thanks,
Haoxin