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

[jakub at gcc dot gnu.org]

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

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I've already bootstrapped
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.

--- gcc/cp/parser.cc.jj 2025-12-17 15:21:21.045719368 +0100
+++ gcc/cp/parser.cc    2025-12-18 11:11:56.074952675 +0100
@@ -20435,7 +20435,7 @@ cp_parser_template_id (cp_parser *parser
                                   fullname, arguments);
       TREE_TYPE (templ)
        = build_typename_type (TYPE_CONTEXT (TREE_TYPE (templ)),
-                              TYPE_NAME (TREE_TYPE (templ)),
+                              TYPE_IDENTIFIER (TREE_TYPE (templ)),
                               fullname,
                               get_typename_tag (TREE_TYPE (templ)));
       template_id = templ;
--- gcc/testsuite/g++.dg/template/crash133.C.jj 2025-12-18 13:22:56.797502427
+0100
+++ gcc/testsuite/g++.dg/template/crash133.C    2025-12-18 13:22:49.365630906
+0100
@@ -0,0 +1,6 @@
+// PR c++/123186
+
+template <class T>
+struct A : T {
+  typename A <T>::template B <42> C;
+};
and am regtesting it right now, but if you want to do something different, go
ahead.