c.opt (Wenum-compare): Enable for C and Objc.

c.opt (Wenum-compare): Enable for C and Objc.

gcc/:
	* c.opt (Wenum-compare): Enable for C and Objc.  Initialize to -1.
	* c-opts.c (c_common_handle_option): For C, set warn_enum_compare
	for -Wall and for -Wc++-compat.
	(c_common_post_options): For C++, set warn_enum_compare if not
	already set.
	* c-tree.h (struct c_expr): Add field original_type.
	(build_external_ref): Update declaration.
	* c-parser.c (c_parser_braced_init): Set original_type.
	(c_parser_initelt): Likewise.
	(c_parser_expr_no_commas): Likewise.
	(c_parser_conditional_expression): Likewise.
	(c_parser_cast_expression): Likewise.
	(c_parser_unary_expression): Likewise.  Pull setting of
	original_code to top of function.
	(c_parser_sizeof_expression): Set original_type.
	(c_parser_alignof_expression): Likewise.
	(c_parser_postfix_expression): Likewise.  Pull setting of
	original_code to top of function.
	(c_parser_postfix_expression_after_paren_type): Set
	original_type.
	(c_parser_postfix_expression_after_primary): Likewise.
	(c_parser_expression): Likewise.
	* c-typeck.c (build_external_ref): Add type parameter.  Change all
	callers.
	(c_expr_sizeof_expr): Set original_type field.
	(parser_build_unary_op): Likewise.
	(parser_build_binary_op): Likewise.  Optionally warn about
	comparisons of enums of different types.
	(digest_init): Set original_type field.
	(really_start_incremental_init): Likewise.
	(push_init_level, pop_init_level): Likewise.
	* doc/invoke.texi (Warning Options): -Wenum-compare now
	supported in C.
gcc/testsuite/:
	* gcc.dg/Wenum-compare-1.c: New testcase.

From-SVN: r146127