c++: unifying equal NONTYPE_ARGUMENT_PACKs [PR102547]
Here during partial ordering of the two partial specializations we end
up in unify with parm=arg=NONTYPE_ARGUMENT_PACK<V0, V1>, and crash shortly
thereafter because uses_template_parms(parms) calls potential_const_expr
which doesn't handle NONTYPE_ARGUMENT_PACK.
This patch fixes this by extending potential_constant_expression to handle
NONTYPE_ARGUMENT_PACK appropriately.
PR c++/102547
gcc/cp/ChangeLog:
* constexpr.c (potential_constant_expression_1): Handle
NONTYPE_ARGUMENT_PACK.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/variadic-partial2.C: New test.
* g++.dg/cpp0x/variadic-partial2a.C: New test.
(cherry picked from commit
d4c470c376b4cb82c9a0b7e8a4b88c44d5e4289d)