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.

0 files changed, 0 insertions, 0 deletions