https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:a834e6d59d74ccaefbcbbed5ea7ee25305057853 commit r10-9634-ga834e6d59d74ccaefbcbbed5ea7ee25305057853 Author: Patrick Palka <ppa...@redhat.com> Date: Sat Sep 19 11:02:46 2020 -0400 c++: Fix self-mapping in map_arguments [PR96531, PR97103] With r10-8077 we stopped passing the argified current_template_parms to normalize_constraint_expression from finish_nested_requirement, and instead made map_arguments perform a self-mapping of parameters when args is NULL. But we're currently not handling parameter packs and BOUND_TEMPLATE_TEMPLATE_PARMs properly during this self-mapping, which leads to ICEs later during satisfaction. To properly handle self-mapping of a parameter pack, this patch extends template_parm_to_arg to handle TEMPLATE_PARM_P nodes, and makes map_arguments use it. (This change revealed that the call to template_parm_to_arg in convert_generic_types_to_packs was a no-op because the argument 't' is never a TREE_LIST, so this patch additionally removes this call.) As for bound ttps, map_arguments before r10-8077 would map a BOUND_TEMPLATE_TEMPLATE_PARM not to itself but to its underlying TEMPLATE_TEMPLATE_PARM. We could restore this behavior in map_arguments, but since a bound ttp is not really a template parameter it seems better to make keep_template_parm not give us a bound ttp in the first place. So this patch makes keep_template_parm return the underlying ttp when it sees a bound ttp. gcc/cp/ChangeLog: PR c++/96531 PR c++/97103 * constraint.cc (map_arguments): Call template_parm_to_arg in the self-mapping case. (finish_shorthand_constraint): No need to build a TREE_LIST before calling template_parm_to_arg. * pt.c (template_parm_to_arg): Rewrite to handle TEMPLATE_PARM_P nodes as well as DECL_TEMPLATE_PARM_P nodes, and to make the overlying TREE_LIST node optional. (keep_template_parm): Don't record a BOUND_TEMPLATE_TEMPLATE_PARM, instead record its corresponding TEMPLATE_TEMPLATE_PARM. (convert_generic_types_to_packs): Don't call template_parm_to_arg. gcc/testsuite/ChangeLog: PR c++/96531 PR c++/97103 * g++.dg/cpp2a/concepts-ttp2.C: New test. * g++.dg/cpp2a/concepts-variadic1.C: New test. (cherry picked from commit e5d72c840a226fdbab65912f97d42a1dbdaf6ed2)
