[Bug libstdc++/110149] std::format for pointer arguments allows a '0' option

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110149

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

https://gcc.gnu.org/g:628ba410b9265dbd4278c1f1b1fadf05348adef2

commit r14-1648-g628ba410b9265dbd4278c1f1b1fadf05348adef2
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Jun 8 21:35:21 2023 +0100

    libstdc++: Fix P2510R3 "Formatting pointers" [PR110149]

    I had intended to support the P2510R3 proposal unconditionally in C++20
    mode, but I left it half implemented. The parse function supported the
    new extensions, but the format function didn't.

    This adds the missing pieces, and makes it only enabled for C++26 and
    non-strict modes.

    libstdc++-v3/ChangeLog:

            PR libstdc++/110149
            * include/std/format (formatter<const void*, charT>::parse):
            Only alow 0 and P for C++26 and non-strict modes.
            (formatter<const void*, charT>::format): Use toupper for P
            type, and insert zero-fill characters for 0 option.
            * testsuite/std/format/functions/format.cc: Check pointer
            formatting. Only check P2510R3 extensions conditionally.
            * testsuite/std/format/parse_ctx.cc: Only check P2510R3
            extensions conditionally.