[Bug c/81656] incompatible _Alignas silently accepted

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81656

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
To be clear: that requirement is not a constraint, so no diagnostic is 
required.  Diagnosis may make sense for _Alignas, but I don't think 
different choices of __attribute__ ((aligned)) should be diagnosed, as a 
matter of compatibility with existing code.