[Bug c++/105725] [ICE] segfault with `-Wmismatched-tags`

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105725

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:bd0c76a2329e7fe6d6612c2259647bbb67f5866a

commit r11-10332-gbd0c76a2329e7fe6d6612c2259647bbb67f5866a
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri May 27 10:51:30 2022 -0400

    c++: Fix ICE with -Wmismatched-tags [PR105725]

    Here we ICE with -Wmismatched-tags on something like

      template <class T>
      bool B<T, enable_if_t<is_class_v<class T::foo>>>;

    Specifically, the "class T::foo" bit.  There, class_decl_loc_t::add gets
    a TYPENAME_TYPE as TYPE, rather than a class/union type, so checking
    TYPE_BEING_DEFINED will crash.  I think it's OK to allow a TYPENAME_TYPE to
    slip into that function; we just shouldn't consider the 'class' tag
redundant
    (which works as a 'typename').  In fact, every other compiler *requires*
it.

            PR c++/105725

    gcc/cp/ChangeLog:

            * parser.c (class_decl_loc_t::add): Check CLASS_TYPE_P.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wmismatched-tags-10.C: New test.

    (cherry picked from commit d822f4bbd714c6595f70cc68888dcebecfb6662d)