[Bug c++/123186] [16 Regression] internal compiler error: in lookup_member, at cp/search.cc:1197 since r16-6145

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123186

--- Comment #8 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:1c555ba67a34ced2460a065eac05ae2e2693ca4d

commit r16-6248-g1c555ba67a34ced2460a065eac05ae2e2693ca4d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Dec 18 16:41:10 2025 +0100

    c++: Fix up recent cp_parser_template_id regression [PR123186]

    On Fri, Dec 12, 2025 at 09:39:18AM -0500, Patrick Palka wrote:
    > +      TREE_TYPE (templ)
    > +     = build_typename_type (TYPE_CONTEXT (TREE_TYPE (templ)),
    > +                            TYPE_NAME (TREE_TYPE (templ)),
    > +                            fullname,
    > +                            get_typename_type_tag (TREE_TYPE (templ)));
    >        template_id = templ;
    >      }
    >    else

    This change causes ICE e.g. on the following testcase.

    The problem is that build_typename_type expects IDENTIFIER_NODE as the
    second argument, e.g. it uses it as
          tree d = build_decl (input_location, TYPE_DECL, name, t);
    argument.  But TYPE_NAME doesn't have to be an IDENTIFIER_NODE, it can
    be a TYPE_DECL too and when we build a TYPE_DECL with TYPE_DECL as
    DECL_NAME, it breaks all kinds of assumptions everywhere in the FE as well
    as middle-end.

    Fixed by using TYPE_IDENTIFIER instead.

    2025-12-18  Jakub Jelinek  <jakub@redhat.com>

            PR c++/123186
            * parser.cc (cp_parser_template_id): Use TYPE_IDENTIFIER instead of
            TYPE_NAME in second build_typename_type argument.

            * g++.dg/template/crash133.C: New test.