c-tree.h (C_DECL_USED, [...]): New.

	* c-tree.h (C_DECL_USED, parser_obstack, in_alignof, in_sizeof,
	in_typeof, record_maybe_used_decl, pop_maybe_used,
	c_expr_sizeof_expr, c_expr_sizeof_type): New.
	* c-decl.c (parser_obstack): New.
	(c_init_decl_processing): Initialize parser_obstack.
	(c_write_global_declarations_1): Check for used but undefined
	static functions.
	* c-parse.in (%union): Add otype.
	(save_obstack_position): New.
	(extdefs): Use it.
	(unary_expr): Update in_sizeof and in_alignof.  Use
	c_expr_sizeof_expr and c_expr_sizeof_type.
	(sizeof): Update in_sizeof.
	(alignof): Update in_alignof.
	(typeof): Update in_typeof.
	(typespec_nonreserved_nonattr): Call pop_maybe_used.
	* c-typeck.c (in_alignof, in_sizeof, in_typeof, struct
	maybe_used_decl, maybe_used_decls, record_maybe_used_decl,
	pop_maybe_used, c_expr_sizeof_expr, c_expr_sizeof_type): New.
	(build_external_ref): Set C_DECL_USED or call
	record_maybe_used_decl if appropriate.
	* toplev.c (check_global_declarations): Check TREE_NO_WARNING.

testsuite:
	* gcc.dg/c90-static-1.c, gcc.dg/c99-static-1.c,
	gcc.dg/gnu99-static-1.c: New tests.

From-SVN: r87216