gcc/ChangeLog:

	PR c/85623
	* calls.c (maybe_warn_nonstring_arg): Use string length to set
	or ajust the presumed bound on an operation to avoid unnecessary
	warnings.

gcc/testsuite/ChangeLog:

	PR c/85623
	* c-c++-common/attr-nonstring-3.c: Adjust.
	* c-c++-common/attr-nonstring-4.c: Adjust.
	* c-c++-common/attr-nonstring-6.c: New test.

From-SVN: r260541