[Bug c++/110106] [11/12/13/14 Regression] ICE on noexcept(noexcept(...)) with optional

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110106

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:e36d1994051122fc6e1f8c728fbd109a59e0a822

commit r14-2717-ge36d1994051122fc6e1f8c728fbd109a59e0a822
Author: Marek Polacek <polacek@redhat.com>
Date:   Tue Jul 18 16:02:21 2023 -0400

    c++: fix ICE with is_really_empty_class [PR110106]

    is_really_empty_class is liable to crash when it gets an incomplete
    or dependent type.  Since r11-557, we pass the yet-uninstantiated
    class type S<0> of the PARM_DECL s to is_really_empty_class -- because
    of the potential_rvalue_constant_expression ->
is_rvalue_constant_expression
    change in cp_parser_constant_expression.  Here we're not parsing
    a template so we did not check COMPLETE_TYPE_P as we should.

    It should work to complete the type before checking COMPLETE_TYPE_P.

            PR c++/110106

    gcc/cp/ChangeLog:

            * constexpr.cc (potential_constant_expression_1): Try to complete
the
            type when !processing_template_decl.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/noexcept80.C: New test.