/gcc
2011-04-25  Paolo Carlini  <paolo.carlini@oracle.com>

	* c-family/c-common.c (struct c_common_resword): Add
	__underlying_type.
	* c-family/c-common.h (enum rid): Add RID_UNDERLYING_TYPE.

/cp
2011-04-25  Paolo Carlini  <paolo.carlini@oracle.com>

	* cp-tree.def: Add a new UNDERLYING_TYPE tree code.
	* cp-tree.h (enum cp_trait_kind): Add CPTK_UNDERLYING_TYPE, tidy.
	(UNDERLYING_TYPE_TYPE): Add.
	* cp-objcp-common.c (cp_common_init_ts): Mark UNDERLYING_TYPE
	as TS_COMMON.
	* parser.c (cp_lexer_next_token_is_decl_specifier_keyword,
	cp_parser_simple_type_specifier): Handle UNDERLYING_TYPE.
	(cp_parser_trait_expr): Deal with RID_UNDERLYING_TYPE; tidy.
	* semantics.c (finish_underlying_type): New.
	* typeck.c (structural_comptypes): Handle UNDERLYING_TYPE.
	* error.c (dump_type, dump_type_prefix, dump_type_suffix): Likewise.
	* cxx-pretty-print.c (p_cxx_type_id): Likewise.
	* tree.c (cp_walk_subtrees): Likewise.
	* pt.c (for_each_template_parm_r, tsubst, unify,
	dependent_type_p_r): Likewise.
	* mangle.c (write_type): Sorry for __underlying_type.
	* doc/extend.texi: Document __underlying_type.

/testsuite
2011-04-25  Paolo Carlini  <paolo.carlini@oracle.com>

	* g++.dg/ext/underlying_type1.C: New.
	* g++.dg/ext/underlying_type2.C: Likewise.
	* g++.dg/ext/underlying_type3.C: Likewise.
	* g++.dg/ext/underlying_type4.C: Likewise.
	* g++.dg/ext/underlying_type5.C: Likewise.
	* g++.dg/ext/underlying_type6.C: Likewise.
	* g++.dg/ext/underlying_type7.C: Likewise.
	* g++.dg/ext/underlying_type8.C: Likewise.
	* g++.dg/ext/underlying_type9.C: Likewise.
	* g++.dg/ext/underlying_type10.C: Likewise.