https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112632
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:f1e5bf0d83ee4da81b6317c6d7f1278fe7eaa5a0 commit r14-8291-gf1e5bf0d83ee4da81b6317c6d7f1278fe7eaa5a0 Author: Jason Merrill <ja...@redhat.com> Date: Wed Jan 17 17:29:33 2024 -0500 c++: alias template argument conversion [PR112632] We've had a problem with lost conversions to template parameter types for a while now; looking at this PR, it occurred to me that the problem is really with alias (and concept) templates, since we do substitution of dependent arguments into them in a way that we don't for other templates. And fixing that specific problem is a lot simpler than adding IMPLICIT_CONV_EXPR around all dependent template arguments the way I gave up on for 111357. The other part of the fix was changing tsubst_expr to actually call convert_nontype_argument instead of assuming it will eventually happen. I waffled about stripping the forced conversion when !force_conv vs. skipping them in iterative_hash_template_arg and template_args_equal (like we already do for some other conversions) and decided to go with the former, but that isn't a strong preference if it turns out to be somehow problematic. PR c++/112632 PR c++/112594 PR c++/111357 PR c++/104594 PR c++/67898 gcc/cp/ChangeLog: * cp-tree.h (IMPLICIT_CONV_EXPR_FORCED): New. * pt.cc (expand_integer_pack): Remove 111357 workaround. (maybe_convert_nontype_argument): Add force parm. (convert_template_argument): Handle alias template args specially. (tsubst_expr): Don't ignore IMPLICIT_CONV_EXPR_NONTYPE_ARG. * error.cc (dump_expr) [CASE_CONVERT]: Handle null optype. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/alias-decl-nontype1.C: New test. * g++.dg/cpp2a/concepts-narrowing1.C: New test. * g++.dg/cpp2a/nontype-class63.C: New test. * g++.dg/cpp2a/nontype-class63a.C: New test.
