[Bug c++/112737] [14 Regression] g++.dg/modules/xtreme-header-2_b.C -std=c++2b (test for excess errors)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112737

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Created attachment 56858
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56858&action=edit
untested fix

Changing CLASS_PLACEHOLDER_TEMPLATE of a CTAD placeholder that names a ttp to
point to the ttp's TEMPLATE_TEMPLATE_PARM node instead of its TEMPLATE_DECL
seems to fix the issue, but I'm not sure if this is what we really want...