PR c++/38796, Core issue 906

PR c++/38796, Core issue 906

	PR c++/38796, Core issue 906
gcc/cp
	* cp-tree.h (DECL_DEFAULTED_OUTSIDE_CLASS_P): New.
	(DECL_DEFAULTED_IN_CLASS_P): New.
	* class.c (user_provided_p): Non-static.
	(check_methods): Use it.
	(check_bases_and_members): Check defaulted fns.
	(defaultable_fn_p): Move and rename to...
	* method.c (defaultable_fn_check): ...this.
	(defaulted_late_check): New.
	* pt.c (tsubst_decl): Call it.
	* decl2.c (grokfield): Adjust.
	* decl.c (cp_finish_decl): Adjust.
	(grok_special_member_properties): Use user_provided_p.
libstdc++-v3
	* include/std/future (~Future_result_base): Default outside class
	body.
	* include/std/system_error (error_category()): Likewise.
	* libsupc++/nested_exception.h (nested_exception): Remove
	exception specifications from defaulted methods.

From-SVN: r153565