[Bug target/90835] Incompatibilities with macOS 10.15 headers

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90835

Iain Sandoe <iains at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |meta-bug
             Blocks|                            |90709
         Depends on|                            |66970

--- Comment #16 from Iain Sandoe <iains at gcc dot gnu.org> ---
I think to make this into a meta-bug, with dependencies on:

__has_builtin () -  PR 66970
__has_feature ()
__has_extension ()
__attribute__((__availability__(....)))
  which depends on __attribute__((__unavailable__(...)))

Martin Sebor has posted a patch for PR 66970 and i have patches in progress for
__has_fature/extension and __attribute__((__unavailable__()))

(I will create PRs for the other deps. in due course)

At the moment, I'm a bit reluctant to jam __has_xxxx => 0 in Darwin startup
code, since that might well produce wrong effects on headers that are already
adjusted (i.e. the compiler would report that __has_xxx was defined, but that
all the facilities were non-existent - which is a different state from
reporting hat __has_xxx is not present).


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66970
[Bug 66970] Add __has_builtin() macro
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90709
[Bug 90709] [meta-bug] GNU Objective C (C++) cannot consume current headers on
Darwin platforms.