* cp-error.def: New file.
	* Make-lang.in (cc1plus): Add dependency on it.
	* Makefile.in (CXX_TREE_H): Likewise.
	* cp-tree.h (error_code): New type.
	Include cp-error.def to get error codes.  Make it possible to
	include cp-tree.h in errfn.c.
	(enable_warning): New function.
	(flag_diag_codes): New variable.
	* errfn.c: Include cp-tree.h.
	(cp_err_msg): New type.  Include cp-error.def to define it.
	(err_msgs): New variable.
	(is_warning_enabled): New function.
	(cp_thing): Take an error_code, not a format string.  Output the
	diagnostic code if flag_diag_codes.
	(cp_error, cp_compiler_error, cp_sprintf, cp_error_at): Take
	error_codes, not format strings.
	(cp_warning, cp_pedwarn, cp_warning_at, cp_pedwarn_at): Likewise.
	Call is_warning_enabled.
	* decl2.c (flag_diag_codes): New variable.
	(lang_decode_option): Handle -fdiag-codes and -Wnumber.
	* lang-options.h: Add -fdiag-codes, -fno-diag-codes, and
	-W-number-, and -Wno-number.
	* class.c: Update all calls to error-functions.
	* cvt.c: Likewise.
	* decl.c: Likewise.
	* decl2.c: Likewise.
	* except.c: Likewise.
	* expr.c: Likewise.
	* friend.c: Likewise.
	* lex.c: Likewise.
	* parse.y: Likewise.
	* pt.c: Likewise.
	* repo.c: Likewise.
	* rtti.c: Likewise.
	* search.c: Likewise.
	* semantics.c: Likewise.
	* sig.c: Likewise.
	* tree.c: Likewise.
	* typeck.c: Likewise.
	* typeck2.c: Likewise.
	* xref.c: Likewise.

From-SVN: r22304