https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96199
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:9125cf8c33b710c378bfb3c7e67ec2f9f1c523c9 commit r11-2747-g9125cf8c33b710c378bfb3c7e67ec2f9f1c523c9 Author: Jason Merrill <ja...@redhat.com> Date: Thu Aug 6 02:40:10 2020 -0400 c++: Handle enumerator in C++20 alias CTAD. [PR96199] To form a deduction guide for an alias template, we substitute the template arguments from the pattern into the deduction guide for the underlying class. In the case of B(A1<X>), that produces B(A1<B<T,1>::X>) -> B<T,1>. But since an enumerator doesn't have its own template info, and B<T,1> is a dependent scope, trying to look up B<T,1>::X fails and we crash. So we need to produce a SCOPE_REF instead. And trying to use the members of the template class is wrong for other members, as well, as it gives a nonsensical result if the class is specialized. gcc/cp/ChangeLog: PR c++/96199 * pt.c (maybe_dependent_member_ref): New. (tsubst_copy) [CONST_DECL]: Use it. [VAR_DECL]: Likewise. (tsubst_aggr_type): Handle nested type. gcc/testsuite/ChangeLog: PR c++/96199 * g++.dg/cpp2a/class-deduction-alias4.C: New test.
