builtin-sprintf-warn-1.c: Add test cases.

gcc/testsuite/ChangeLog:
	* gcc.dg/tree-ssa/builtin-sprintf-warn-1.c: Add test cases.

From-SVN: r244999

gcc/testsuite/ChangeLog

+2017-01-27  Martin Sebor  <msebor@redhat.com>
+
+	* gcc.dg/tree-ssa/builtin-sprintf-warn-1.c: Add test cases.
+
 2017-01-27  Bernd Schmidt  <bschmidt@redhat.com>
 
 	PR rtl-optimization/79194

gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-1.c

@@ -76,10 +76,24 @@ int dummy___vsnprintf_chk (char*, size_t, int, size_t, const char*, va_list);
 /* Macro to verify that calls to __builtin_sprintf (i.e., with no size
    argument) issue diagnostics by correctly determining the size of
    the destination buffer.  */
-#define T(size, fmt, ...)						\
-  (FUNC (sprintf) (buffer (size), fmt, __VA_ARGS__),			\
+#define T(size, ...)						\
+  (FUNC (sprintf) (buffer (size),  __VA_ARGS__),		\
    sink (buffer, ptr))
 
+/* Exercise the "%%" directive.  */
+
+void test_sprintf_percent (void)
+{
+  T (-1, "%%");
+  T ( 0, "%%");                 /* { dg-warning ".%%. directive writing 1 byte into a region of size 0" } */
+  T ( 1, "%%");                 /* { dg-warning "writing a terminating nul past the end" } */
+  T ( 2, "%%");
+  T ( 2, "%%%%");               /* { dg-warning "writing a terminating nul past the end" } */
+  T ( 3, "%%%%");
+  T ( 3, "%%X%%");              /* { dg-warning "writing a terminating nul past the end" } */
+  T ( 4, "%%X%%");
+}
+
 /* Exercise the "%c" and "%lc" directive with constant arguments.  */
 
 void test_sprintf_c_const (void)