[Bug libstdc++/86843] Allow separating debug mode into ABI-changing part and rest

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86843

--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Iain D Sandoe <iains@gcc.gnu.org>:

https://gcc.gnu.org/g:08776bef53835ff6318ecfeade8f6c6896ffd81f

commit r15-2009-g08776bef53835ff6318ecfeade8f6c6896ffd81f
Author: Daniel Bertalan <dani@danielbertalan.dev>
Date:   Tue Jul 9 23:34:46 2024 +0200

    Fix Xcode 16 build break with NULL != nullptr

    As of Xcode 16 beta 2 with the macOS 15 SDK, each re-inclusion of the
    stddef.h header causes the NULL macro in C++ to be re-defined to an
    integral constant (__null). This makes the workaround in d59a576b8
    ("Redefine NULL to nullptr") ineffective, as other headers that are
    typically included after system.h (such as obstack.h) do include
    stddef.h too.

    This can be seen by running the sample below through `clang++ -E`

        #include <stddef.h>
        #define NULL nullptr
        #include <stddef.h>
        NULL

    The relevant libc++ change is here:
   
https://github.com/llvm/llvm-project/commit/2950283dddab03c183c1be2d7de9d4999cc86131

    Filed as FB14261859 to Apple and added a comment about it on LLVM PR
    86843.

    This fixes the cases in --enable-languages=c,c++,objc,obj-c++,rust build
    where NULL being an integral constant instead of a null pointer literal
    (therefore no longer implicitly converting to a pointer when used as a
    template function's argument) caused issues.

        gcc/value-pointer-equiv.cc:65:43: error: no viable conversion from
`pair<typename __unwrap_ref_decay<long>::type, typename
__unwrap_ref_decay<long>::type>' to 'const pair<tree, tree>'

        65 |   const std::pair <tree, tree> m_marker = std::make_pair (NULL,
NULL);
           |                                          
^~~~~~~~~~~~~~~~~~~~~~~~~~~

    As noted in the previous commit though, the proper solution would be to
    phase out the usages of NULL in GCC's C++ source code.

    gcc/analyzer/ChangeLog:

            * diagnostic-manager.cc (saved_diagnostic::saved_diagnostic):
            Change NULL to nullptr.
            (struct null_assignment_sm_context): Likewise.
            * infinite-loop.cc: Likewise.
            * infinite-recursion.cc: Likewise.
            * varargs.cc (va_list_state_machine::on_leak): Likewise.

    gcc/rust/ChangeLog:

            * metadata/rust-imports.cc (Import::try_package_in_directory):
            Change NULL to nullptr.

    gcc/ChangeLog:

            * value-pointer-equiv.cc: Change NULL to nullptr.

    Signed-off-by: Daniel Bertalan <dani@danielbertalan.dev>