re PR c/50459 (alignof doesn't work on plain old constant, works with expressions...

re PR c/50459 (alignof doesn't work on plain old constant, works with expressions containing it)

	PR c/50459
c-family/
	* c-common.c (check_user_alignment): Return -1 if alignment is error
	node.
	(handle_aligned_attribute): Don't call default_conversion on
	FUNCTION_DECLs.
	(handle_vector_size_attribute): Likewise.
	(handle_tm_wrap_attribute): Handle case when wrap_decl is error node.
	(handle_sentinel_attribute): Call default_conversion and allow even
	integral types as an argument.
c/
	* c-parser.c (c_parser_attributes): Parse the arguments as an
	expression-list if the attribute takes identifier.
testsuite/
	* c-c++-common/attributes-1.c: Move test line to a new test.
	* c-c++-common/attributes-2.c: New test.
	* c-c++-common/pr50459.c: New test.
	* c-c++-common/pr59280.c: Add "undeclared" to dg-error.
	* gcc.dg/nonnull-2.c: Likewise.
	* gcc.dg/pr55570.c: Modify dg-error.
	* gcc.dg/tm/wrap-2.c: Likewise.

From-SVN: r210262