[Bug c++/114275] using std::thread within a templated function in a module fails to compile

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114275

--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathaniel Shead <nshead@gcc.gnu.org>:

https://gcc.gnu.org/g:ec2365e07537e8b17745d75c28a2b45bf33be119

commit r15-220-gec2365e07537e8b17745d75c28a2b45bf33be119
Author: Nathaniel Shead <nathanieloshead@gmail.com>
Date:   Fri May 3 19:36:17 2024 +1000

    c++/modules: Fix dangling pointer with imported_temploid_friends

    I got notified by Linaro CI and by checking testresults that there seems
    to be some occasional failures in tpl-friend-4_b.C on some architectures
    and standards modes since r15-59-gb5f6a56940e708.  I haven't been able
    to reproduce but looking at the backtrace I suspect the issue is that
    we're adding to the 'imported_temploid_friend' map a decl that is
    ultimately discarded, which then has its address reused by a later decl
    causing a failure in the assert in 'set_originating_module'.

    This patch fixes the problem by ensuring 'imported_temploid_friends' is
    correctly marked as a GTY root, and that 'duplicate_decls' properly
    removes entries from the map for declarations that it frees.

            PR c++/114275

    gcc/cp/ChangeLog:

            * cp-tree.h (remove_defining_module): Declare.
            * decl.cc (duplicate_decls): Call remove_defining_module on
            to-be-freed newdecl.
            * module.cc (imported_temploid_friends): Mark as GTY root...
            (init_modules): ...and allocate from ggc.
            (trees_in::decl_value): Only track for declarations that won't
            be discarded.
            (remove_defining_module): New function.

    Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
    Reviewed-by: Jason Merrill <jason@redhat.com>
    Reviewed-by: Patrick Palka <ppalka@redhat.com>