Re: stdalign test with HP-UX cc

[Paul Eggert]

Bruno Haible wrote:
> Since I don't have access to a newer HP-UX cc compiler, I propose to just
> disable this definition for HP-UX cc. This patch fixes the error.

That sounds too drastic; I worry that it would break GNU Emacs, which relies on 
having alignas.

Does Emacs 25.1 build with that compiler? If so, could you investigate why Enacs 
works, whereas the stdalign test fails? Emacs 25.1 should be using 
lib/stdalign.in.h. If it works for Emacs and fails for tests/test-stdalign.c, 
then the latter is probably just too picky.

I don't have access to any HP-UX cc, unfortunately. MariaDB 10.1.22 
include/my_compiler.h uses this test:

  #elif defined(__HP_aCC) || defined(__HP_cc)
  # if (__HP_aCC >= 60000) || (__HP_cc >= 60000)

and Qt 4, which I think worries only about C++, has the equivalent of:

  #if __cplusplus >= 199707L && __HP_aCC-0 >= 061200

(though it uses '__attribute__((aligned(n))', not '__attribute__ ((__aligned__ 
(n)))'). I expect it's Qt that I got the "061200" from. At this point these 
compiler-version numbers are so old it will be difficult to find out whether 
they were really supposed to be octal or decimal, way back when.

Does it fix things to replace '__attribute__ ((__aligned__ (n)))' with 
'__attribute__((aligned(n))' in lib/stdalign.in.h? If so, we could use that as a 
workaround. This is a long-shot, admittedly.