[Bug c++/105593] avx512 math function raises uninitialized variable warning

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105593

--- Comment #29 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:732d744e82332e7cc269694197c0df2a3635730f

commit r12-9161-g732d744e82332e7cc269694197c0df2a3635730f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Jan 16 09:40:14 2023 +0100

    c, c++: Allow ignoring -Winit-self through pragmas [PR105593]

    As mentioned in the PR, various x86 intrinsics need to return
    an uninitialized vector.  Currently they use self initialization
    to avoid -Wuninitialized warnings, which works fine in C, but
    doesn't work in C++ where -Winit-self is enabled in -Wall.
    We don't have an attribute to mark a variable as knowingly
    uninitialized (the uninitialized attribute exists but means
    something else, only in the -ftrivial-auto-var-init context),
    and trying to suppress either -Wuninitialized or -Winit-self
    inside of the _mm_undefined_ps etc. intrinsic definitions
    doesn't work, one needs to currently disable through pragmas
    -Wuninitialized warning at the point where _mm_undefined_ps etc.
    result is actually used, but that goes against the intent of
    those intrinsics.

    The -Winit-self warning option actually doesn't do any warning,
    all we do is record a suppression for -Winit-self if !warn_init_self
    on the decl definition and later look that up in uninit pass.

    The following patch changes those !warn_init_self tests which
    are true only based on the command line option setting, not based
    on GCC diagnostic pragma overrides to
    !warning_enabled_at (DECL_SOURCE_LOCATION (decl), OPT_Winit_self)
    such that it takes them into account.

    2023-01-16  Jakub Jelinek  <jakub@redhat.com>

            PR c++/105593
    gcc/c/
            * c-parser.cc (c_parser_initializer): Check warning_enabled_at
            at the DECL_SOURCE_LOCATION (decl) for OPT_Winit_self instead
            of warn_init_self.
    gcc/cp/
            * decl.cc (cp_finish_decl): Check warning_enabled_at
            at the DECL_SOURCE_LOCATION (decl) for OPT_Winit_self instead
            of warn_init_self.
    gcc/testsuite/
            * c-c++-common/Winit-self3.c: New test.
            * c-c++-common/Winit-self4.c: New test.
            * c-c++-common/Winit-self5.c: New test.

    (cherry picked from commit 98b41fd4045b7856e7b85dd58d67c600bd909379)