https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110122
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:682d401a6ba723b2bf98779d056efc8ff2640178 commit r14-1697-g682d401a6ba723b2bf98779d056efc8ff2640178 Author: Patrick Palka <ppa...@redhat.com> Date: Sun Jun 11 11:09:16 2023 -0400 c++: extend lookup_template_class shortcut [PR110122] Here when substituting the injected class name A during regeneration of the lambda, we find ourselves in lookup_template_class for A<V> with V=_ZTAXtl3BarEE (i.e. the template parameter object for Foo{}). The call to coerce_template_parms within then undesirably tries to make a copy of this class NTTP argument, which fails because Foo is not copyable. But it seems clear that this testcase shouldn't require copyability of Foo. lookup_template_class has a shortcut for looking up the current class scope, which would avoid the problematic coerce_template_parms call, but the shortcut doesn't trigger because it only considers the innermost class scope which in this case in the lambda type. So this patch fixes this by extending the lookup_template_class shortcut to consider outer class scopes too (and skipping over lambda types since they are never specialized from lookup_template_class). We also need to avoid calling coerce_template_parms when specializing a templated non-template nested class for the first time (such as A::B in the testcase). Coercion should be unnecessary there because the innermost arguments belong to the context and so should have already been coerced. PR c++/110122 gcc/cp/ChangeLog: * pt.cc (lookup_template_class): Extend shortcut for looking up the current class scope to consider outer class scopes too, and use current_nonlambda_class_type instead of current_class_type. Only call coerce_template_parms when specializing a primary template. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/nontype-class57.C: New test. * g++.dg/cpp2a/nontype-class58.C: New test.
