PR middle-end/85602 - -Wsizeof-pointer-memaccess for strncat with size of source

PR middle-end/85602 - -Wsizeof-pointer-memaccess for strncat with size of source

gcc/c-family/ChangeLog:

	PR middle-end/85602
	* c-warn.c (sizeof_pointer_memaccess_warning): Check for attribute
	nonstring.

gcc/ChangeLog:

	PR middle-end/85602
	* calls.c (maybe_warn_nonstring_arg): Handle strncat.
	* tree-ssa-strlen.c (is_strlen_related_p): Make extern.
	Handle integer subtraction.
	(maybe_diag_stxncpy_trunc): Handle nonstring source arguments.
	* tree-ssa-strlen.h (is_strlen_related_p): Declare.

gcc/testsuite/ChangeLog:

	PR middle-end/85602
	* gcc.dg/attr-nonstring-2.c: Adjust text of expected warning.
	* c-c++-common/attr-nonstring-8.c: New test.

From-SVN: r261718