re PR c++/50732 ([type_traits] is_base_of<Base, Derived> unnecessarily instantiates Base (which shouldn't be instantiated))

/cp
2011-10-15  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/50732
	* semantics.c (finish_trait_expr): Do not try to instantiate the
	the base type of an __is_base_of trait.
	(check_trait_type): Return a tree; use complete_type_or_else.

/testsuite
2011-10-15  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/50732
	* g++.dg/ext/is_base_of_incomplete.C: New.
	* g++.dg/ext/is_base_of_diagnostic.C: Adjust dg-errors.
	* g++.dg/ext/unary_trait_incomplete.C: Likewise.

From-SVN: r180048