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Subject: [Bug c++/94716] comparison of address of template variables should
 be constexpr
Date: Mon, 03 Jan 2022 12:48:46 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94716

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:91031bffa42fdea3c985727d042cd1882a64be9c

commit r12-6188-g91031bffa42fdea3c985727d042cd1882a64be9c
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Jan 3 13:47:53 2022 +0100

    symtab: Fold &a =3D=3D &b to 0 if folding_initializer [PR94716]

    On Thu, Dec 09, 2021 at 06:09:12PM -0500, Jason Merrill wrote:
    > For the more general comparison of decls like your a !=3D b example a=
bove I
    > think clang is in the right; in manifestly constant-evaluated context
    > (folding_initializer) we should return that they are unequal and prev=
ent
a
    > later alias declaration, like we do for comparison to 0 in
    > maybe_nonzero_address.  It's possible that this gives a wrong answer
based
    > on something in another translation unit, but that's unlikely, and ta=
king
    > that chance seems better than rejecting code that needs a constant
answer.

    I agree.  This is an incremental patch to do that.

    2022-01-03  Jakub Jelinek  <jakub@redhat.com>

            PR c++/94716
    gcc/
            * symtab.c: Include fold-const.h.
            (symtab_node::equal_address_to): If folding_initializer is true,
            handle it like memory_accessed.  Simplify.
    gcc/testsuite/
            * gcc.dg/init-compare-1.c: New test.
            * g++.dg/cpp0x/constexpr-compare1.C: New test.
            * g++.dg/cpp1y/constexpr-94716.C: New test.
            * g++.dg/cpp1z/constexpr-compare1.C: New test.=