Re: [PATCH] Improve sequence logic in cxx_init_decl_processing

[Jason Merrill <jason@redhat.com>]

On 1/6/22 03:26, Olivier Hainque wrote:
> Hello,
> 
> commit aa2c978400f3b3ca6e9f2d18598a379589e77ba0, introduced per
> 
>    https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545552.html
> 
> makes references to __cxa_pure_virtual weak and this is causing
> issues on some VxWorks configurations, where weak symbols are only
> supported for one of the two major operating modes, and not on all
> versions.
> 
> While trying to circumvent that, I noticed that the current
> code in cxx_init_decl_processing does something like:
> 
>    if (flag_weak)
>      /* If no definition is available, resolve references to NULL.  */
>      declare_weak (abort_fndecl);
>    ...
>    if (! supports_one_only ())
>      flag_weak = 0;
> 
> 
> The code possibly resetting flag_weak should presumlably execute
> before the test checking the flag, or we'd need a comment explaining
> why this surprising order is on purpose.
> 
> The attached patch just moves the reset above the test.
> 
> It bootstraps/regtests fine on x86_64-linux and allows better control
> on vxWorks. I'm not yet clear on some of the ramifications there (tigthening
> the definitions of SUPPORTS_ONE_ONLY and TARGET_SUPPORTS_WEAK yields lots of
> dg test failures) but that's another story.
> 
> Ok to commit?

OK.

> Thanks in advance!
> 
> 2021-12-30  Olivier Hainque  <hainque@adacore.com>
> 
> gcc/
> 	* cp/decl.c (cxx_init_decl_processing): Move code possibly
> 	altering flag_weak before code testing it.
> 
> Olivier
> 
> 
> 
> 
>