c++/modules: Don't treat template parameters as TU-local [PR118846]

c++/modules: Don't treat template parameters as TU-local [PR118846]

There are two separate issues making various template parameters behave
as if they were TU-local.

Firstly, the TU-local detection code uses WILDCARD_TYPE_P to check for
types that are not yet concrete; for some reason UNBOUND_CLASS_TEMPLATE
is not on that list.  I don't see any particular reason why it shouldn't
be, so this patch adds it; this may solve other latent issues as well.

Secondly, the TEMPLATE_DECL for a type with expressions involving
TEMPLATE_TEMPLATE_PARM_Ps is currently always constrained to internal
linkage, because the result does not have TREE_PUBLIC set. Rather than
messing with TREE_PUBLIC here, I think rather we just should ensure that
we only attempt to constrain visiblity of templates of type, variable,
or function decls.

	PR c++/118846

gcc/cp/ChangeLog:

	* cp-tree.h (WILDCARD_TYPE_P): Include UNBOUND_CLASS_TEMPLATE.
	* decl2.cc (min_vis_expr_r): Don't assume a TEMPLATE_DECL will
	be a function or variable.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/pr118846_a.C: New test.
	* g++.dg/modules/pr118846_b.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
Reviewed-by: Jason Merrill <jason@redhat.com>