[Bug c++/101043] ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:40a7707a7ea3568cee2cd80cd7e83b7eda678410

commit r14-5504-g40a7707a7ea3568cee2cd80cd7e83b7eda678410
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Nov 15 12:17:55 2023 -0500

    c++: partially inst requires-expr in noexcept-spec [PR101043]

    Here we're ICEing from strip_typedefs for the partially instantiated
    requires-expression when walking its REQUIRES_EXPR_EXTRA_ARGS which
    in this case is a TREE_LIST with non-empty TREE_PURPOSE (to hold the
    captured local specialization 't' as per build_extra_args) which
    strip_typedefs doesn't expect.

    We can probably skip walking REQUIRES_EXPR_EXTRA_ARGS at all since it
    shouldn't contain any typedefs in the first place, but it seems safer
    and more generally useful to just teach strip_typedefs to handle non-empty
    TREE_PURPOSE the obvious way.  (The code asserts TREE_PURPOSE was empty
    even since since its inception i.e. r189298.)

            PR c++/101043

    gcc/cp/ChangeLog:

            * tree.cc (strip_typedefs_expr) <case TREE_LIST>: Handle
            non-empty TREE_PURPOSE.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-requires37.C: New test.