[Bug c++/117849] constraint variable in requires expression rejected, but P2280R4 made it valid

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117849

--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-14 branch has been updated by Patrick Palka
<ppa...@gcc.gnu.org>:

https://gcc.gnu.org/g:49b6308d2596f7334011f84bae8d35d68c302a3c

commit r14-11529-g49b6308d2596f7334011f84bae8d35d68c302a3c
Author: Patrick Palka <ppa...@redhat.com>
Date:   Fri Apr 4 14:03:58 2025 -0400

    c++: constraint variable used in evaluated context [PR117849]

    Here we wrongly reject the type-requirement at parse time due to its use
    of the constraint variable 't' within a template argument (an evaluated
    context).  Fix this simply by refining the "use of parameter outside
    function body" error path to exclude constraint variables.

    PR c++/104255 tracks the same issue for function parameters, but fixing
    that would be more involved, requiring changes to the PARM_DECL case of
    tsubst_expr.

            PR c++/117849

    gcc/cp/ChangeLog:

            * semantics.cc (finish_id_expression_1): Allow use of constraint
            variable outside an unevaluated context.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-requires41.C: New test.

    Reviewed-by: Jason Merrill <ja...@redhat.com>
    (cherry picked from commit 6e973e87e3fec6f33e97edf8fce2fcd121e53961)