[Bug c++/125376] Distinct C++26 placeholder variables (P2169) share storage inside coroutine frames

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125376

--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-16 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:58d805dc29e883bc41b9e14e518a1c88c5a186d3

commit r16-9031-g58d805dc29e883bc41b9e14e518a1c88c5a186d3
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu May 21 16:26:22 2026 +0200

    c++: Fix up handling of name independent decls in coroutine lowering
[PR125376]

    For variables which do have non-NULL DECL_NAME, register_local_var_uses
    uses either that name or name_depth_idx (that itself is a bug as it
    can clash with user variables named that way) for the fields.  In C++26
    we can have multiple _ variables in the same scope, so the following
    testcase is miscompiled by using the same FIELD_DECL multiple times
    (once for the first _ variable, once for the second one).

    The following patch fixes it by pretending such variables don't have
    a name, so it uses a serial number then instead.

    2026-05-21  Jakub Jelinek  <jakub@redhat.com>

            PR c++/125376
            * coroutines.cc (register_local_var_uses): Ignore DECL_NAME for
            name independent decls.

            * g++.dg/coroutines/pr125376.C: New test.

    (cherry picked from commit 960e68941db7412cfdfb429161d77db206a06acc)