[Bug c++/108179] [11/12/13 regression] ICE related to template template parameters in tsubst, at cp/pt.cc:15782

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108179

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:3ea64aad06a2b32739028bae03b9b9a5691d2d30

commit r13-6693-g3ea64aad06a2b32739028bae03b9b9a5691d2d30
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Mar 10 14:55:27 2023 -0500

    c++: passing one ttp to another [PR108179]

    I kept trying to improve our choice of how many levels of outer_args to
add,
    when really the problem was that outer_args are for PARM and for this
    reverse deduction we should be adding the outer arguments for ARG.

    I spent quite a while trying to get DECL_CONTEXT set consistently on
    template template parameters that have gone through
    reduce_template_parm_level before I realized I could just use
    current_scope().

            PR c++/108179
            PR c++/104107
            PR c++/95036

    gcc/cp/ChangeLog:

            * pt.cc (coerce_template_template_parms): Use args from
            DECL_CONTEXT (arg_tmpl) instead of outer_args.

    gcc/testsuite/ChangeLog:

            * g++.dg/template/ttp35.C: New test.