* builtins.c (unterminated_array): Handle ARRAY_REF.
	(expand_builtin_stpcpy_1): Detect unterminated char arrays.
	* builtins.h (unterminated_array): Declare extern.
	* gimple-fold.c (gimple_fold_builtin_stpcpy): Detect unterminated
	  arrays.
	(gimple_fold_builtin_sprintf): Propagate NO_WARNING to transformed
	calls.

	* gcc.dg/warn-stpcpy-no-nul.c: New test.

From-SVN: r264328