[Bug c++/103105] [11 Regression] ICE iterative_hash_template_arg with concepts and varagrs template since r11-3261-gb28b621ac67beee8

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103105

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:051d304ce8e2173bd0cb721ed91d4a1fefa61d87

commit r11-9839-g051d304ce8e2173bd0cb721ed91d4a1fefa61d87
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Apr 12 12:58:18 2022 -0400

    c++: requires-expr in pack expansion using pack [PR103105]

    Here after dependent substitution of {Ts...} into the alias 'wrap',
    since we never partially instantiate a requires-expr, we end up with a
    requires-expr whose REQUIRES_EXPR_EXTRA_ARGS contains an
    ARGUMENT_PACK_SELECT (which just resolves to the parameter pack Ts).
    Then when hashing the resulting dependent specialization of A, we crash
    from iterative_hash_template_arg since it deliberately doesn't handle
    ARGUMENT_PACK_SELECT.

    Like in r12-7102-gdb5f1c17031ad8, it seems the right fix here is to
    resolve ARGUMENT_PACK_SELECT arguments before storing them into an
    extra args tree (such as REQUIRES_EXPR).

            PR c++/103105

    gcc/cp/ChangeLog:

            * pt.c (build_extra_args): Call preserve_args.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-requires29.C: New test.
            * g++.dg/cpp2a/concepts-requires29a.C: New test.

    (cherry picked from commit e2c7070ac7740508a7c49bfee9f895e216a272d6)