[Bug c++/114426] [14 regression] ICE when building log4cxx on arm (cxx_eval_call_expression, at cp/constexpr.cc:3242) since r14-6507

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114426

--- Comment #12 from GCC 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:0fd824d717ca901319864a5eeba4e62b278f8329

commit r14-9942-g0fd824d717ca901319864a5eeba4e62b278f8329
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Apr 12 19:57:04 2024 +0200

    c++: Diagnose or avoid constexpr dtors in classes with virtual bases
[PR114426]

    I had another look at this P1 PR today.
    You said in the "c++: fix in-charge parm in constexpr" mail back in
December
    (as well as in the r14-6507 commit message):
    "Since a class with vbases can't have constexpr 'tors there isn't actually
    a need for an in-charge parameter in a destructor" but the ICE is because
    the destructor is marked implicitly constexpr.
    https://eel.is/c++draft/dcl.constexpr#3.2 says that a destructor of a class
    with virtual bases is not constexpr-suitable, but we were actually
    implementing this just for constructors, so clearly my fault from the
    https://wg21.link/P0784R7 implementation.  That paper clearly added that
    sentence in there and removed similar sentence just from the constructor
case.

    So, the following patch makes sure the
      else if (CLASSTYPE_VBASECLASSES (DECL_CONTEXT (fun)))
        {
          ret = false;
          if (complain)
            error ("%q#T has virtual base classes", DECL_CONTEXT (fun));
        }
    hunk is done no just for DECL_CONSTRUCTOR_P (fun), but also
    DECL_DESTRUCTOR_P (fun) - in that case just for cxx_dialect >= cxx20,
    as for cxx_dialect < cxx20 we already set ret = false; and diagnose
    a different error, so no need to diagnose two.

    2024-04-12  Jakub Jelinek  <jakub@redhat.com>

            PR c++/114426
            * constexpr.cc (is_valid_constexpr_fn): Return false/diagnose with
            complain destructors in classes with virtual bases.

            * g++.dg/cpp2a/pr114426.C: New test.
            * g++.dg/cpp2a/constexpr-dtor16.C: New test.