The problem here was that we were checking satisfaction once with 'e', a
typedef of 'void', and another time with 'void' directly, and treated them
as different for hashing based on the assumption that
canonicalize_type_argument would have already removed a typedef that wasn't
a complex dependent alias.  But that wasn't happening here, so let's add a
call.

gcc/cp/ChangeLog
2020-03-11  Jason Merrill  <jason@redhat.com>

	PR c++/93907
	* constraint.cc (tsubst_parameter_mapping): Canonicalize type
	argument.