PR c++/6709 (DR 743)

	PR c++/6709 (DR 743)
	PR c++/42603 (DR 950)
gcc/cp/
	* parser.c (token_is_decltype, cp_lexer_next_token_is_decltype): New.
	(cp_parser_nested_name_specifier_opt): Allow decltype.
	(cp_parser_qualifying_entity): Likewise.
	(cp_parser_decltype): Replace source tokens with CPP_DECLTYPE.
	(cp_parser_simple_type_specifier): Handle decltype as scope.
	(cp_parser_base_specifier): Allow decltype.
	(cp_parser_base_clause): Don't crash on null base.
	* parser.h (CPP_KEYWORD, CPP_TEMPLATE_ID): Move to c-common.h.
	(CPP_NESTED_NAME_SPECIFIER, N_CP_TTYPES): Likewise.
gcc/c-family/
	* c-common.h (CPP_KEYWORD, CPP_TEMPLATE_ID): Move from cp/parser.h.
	(CPP_NESTED_NAME_SPECIFIER, N_CP_TTYPES): Likewise.
	(CPP_DECLTYPE): New.
	* c-common.c (c_parse_error): Handle CPP_DECLTYPE.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@176513 138bc75d-0d04-0410-961f-82ee72b054a4