[Bug c++/123913] [reflection] Internal Compiler Error in eval_is_function_parameter at cp/reflect.cc:1656 materializing function type parameters

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123913

--- Comment #5 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:8bc8aaed6c22fac5f66be11e92001665c20716ef

commit r16-7281-g8bc8aaed6c22fac5f66be11e92001665c20716ef
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Feb 4 12:30:42 2026 +0100

    c++: Fix up eval_parameters_of for function types [PR123913]

    eval_parameters_of was trying to share 3 lines of code between the
    function declaration and function type cases, but got it wrong in
    multiple ways for the latter.  One thing is that we should override
    reflect_kind only for the function decl case to REFLECT_PARM, there
    we need to differentiate function parameter reflection vs. variable
    reflection, for function type it is just type.  Another one is that
    we iterate over PARM_DECLs through DECL_CHAIN in the function decl
    case, but for types we iterate over the TREE_LIST nodes and the
    type is only TREE_VALUE of that.
    And last, but am not sure about that, maybe
    https://eel.is/c++draft/meta.reflection#queries-62.2 should be clarified,
    I think we want to apply dealias.  We have notes like
    https://eel.is/c++draft/meta.reflection#queries-note-7
    https://eel.is/c++draft/meta.reflection#traits-5
    but those don't apply to type_of or parameters_of.  And I think there was
    an agreement that meta fns which return reflection of a type don't return
    type aliases, but can't see it written explicitly except for the traits.

    2026-02-04  Jakub Jelinek  <jakub@redhat.com>

            PR c++/123913
            PR c++/123964
            * reflect.cc (eval_parameters_of): Fix up handling of function
            types.

            * g++.dg/reflect/parameters_of7.C: New test.