[Bug libstdc++/97132] assume_aligned is not constexpr

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97132

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:77923ad01415f6e72af844cbef5227f5b5a9fb4b

commit r9-9003-g77923ad01415f6e72af844cbef5227f5b5a9fb4b
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Sep 21 14:28:58 2020 +0100

    libstdc++: Make std::assume_aligned a constexpr function [PR 97132]

    The cast from void* to T* in std::assume_aligned is not valid in a
    constexpr function. The optimization hint is redundant during constant
    evaluation anyway (the compiler can see the object and knows its
    alignment). Simply return the original pointer without applying the
    __builtin_assume_aligned hint to it when doing constant evaluation.

    libstdc++-v3/ChangeLog:

            PR libstdc++/97132
            * include/std/memory (assume_aligned): Do not use
            __builtin_assume_aligned during constant evaluation.
            * testsuite/20_util/assume_aligned/1.cc: Improve test.
            * testsuite/20_util/assume_aligned/97132.cc: New test.

    (cherry picked from commit f10ed928e2f8ecc2c859abff8f2f9296b11b8d95)