re PR c/13519 (typeof(nonconst+const) is const)

re PR c/13519 (typeof(nonconst+const) is const)

	PR c/13519
	* c-typeck.c (composite_type, common_pointer_type): New functions.
	(common_type): Split parts into composite_type and
	common_pointer_type.  Ensure that arithmetic operations return
	unqualified types without attributes.  Don't make composite type
	of signed enum and compatible integer be unsigned.
	(build_conditional_expr, build_binary_op): Use
	common_pointer_type.
	* c-decl.c (merge_decls): Use composite_type.
	* c-tree.h (composite_type): Declare.

testsuite:
	* gcc.c-torture/enum-3.c, gcc.dg/pr13519-1.c: New tests.

From-SVN: r82671