type_traits: Implement is_abstract, by exploiting the resolution of DR core/337.

type_traits: Implement is_abstract, by exploiting the resolution of DR core/337.

2005-01-28  Paolo Carlini  <pcarlini@suse.de>

	* include/tr1/type_traits: Implement is_abstract, by exploiting the
	resolution of DR core/337.
	* testsuite/testsuite_tr1.h: Add AbstractClass.
	* testsuite/tr1/4_metaprogramming/type_properties/is_abstract/
	is_abstract.cc: New.
	* testsuite/tr1/4_metaprogramming/type_properties/is_abstract/
	typedefs.cc: Likewise.

	* include/tr1/type_traits (is_function): Rewrite, use the conversion
	F& -> F* instead, thus avoiding problems with abstract classes.
	* testsuite/tr1/4_metaprogramming/primary_type_categories/
	is_function/is_function.cc: Add a test for tricky AbstractClass.

From-SVN: r94370