--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/c-c++-common/Wstringop-truncation-2.c	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,105 @@
+/* Verify that 
+   { dg-do compile }
+   { dg-options "-O2 -Wstringop-truncation -Wno-stringop-overflow -ftrack-macro-expansion=0" } */
+
+typedef __SIZE_TYPE__ size_t;
+
+#define stpncpy(d, s, n) __builtin_stpncpy ((d), (s), (n))
+#define strncpy(d, s, n) __builtin_stpncpy ((d), (s), (n))
+
+void sink (void*);
+
+struct A {
+  char arr[3] __attribute__ ((nonstring));
+  char str[3];
+};
+
+struct B { struct A a[3]; int i; };
+struct C { struct B b[3]; int i; };
+
+void stpncpy_arr_1 (struct C *pc, const char *s)
+{
+  stpncpy (pc->b[0].a[0].arr, s, sizeof pc->b[0].a[0].arr);
+  sink (pc->b[0].a[0].arr);
+
+  stpncpy (pc->b[0].a[1].arr, s, sizeof pc->b[0].a[1].arr);
+  sink (pc->b[0].a[1].arr);
+
+  stpncpy (pc->b[0].a[2].arr, s, sizeof pc->b[0].a[2].arr);
+  sink (pc->b[0].a[2].arr);
+
+  stpncpy (pc->b[1].a[0].arr, s, sizeof pc->b[1].a[0].arr);
+  sink (pc->b[1].a[0].arr);
+
+  stpncpy (pc->b[1].a[1].arr, s, sizeof pc->b[1].a[1].arr);
+  sink (pc->b[1].a[1].arr);
+
+  stpncpy (pc->b[1].a[2].arr, s, sizeof pc->b[1].a[2].arr);
+  sink (pc->b[1].a[2].arr);
+
+  stpncpy (pc->b[2].a[0].arr, s, sizeof pc->b[2].a[0].arr);
+  sink (pc->b[2].a[0].arr);
+
+  stpncpy (pc->b[2].a[1].arr, s, sizeof pc->b[2].a[1].arr);
+  sink (pc->b[2].a[1].arr);
+
+  stpncpy (pc->b[2].a[2].arr, s, sizeof pc->b[2].a[2].arr);
+  sink (pc->b[2].a[2].arr);
+}
+
+void stpncpy_str_nowarn_1 (struct C *pc, const char *s)
+{
+  stpncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str)[-1] = 0;   /* { dg-bogus "\\\[-Wstringop-truncation" } */
+}
+
+void stpncpy_str_nowarn_2 (struct C *pc, const char *s)
+{
+  *stpncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str - 1) = 0;   /* { dg-bogus "\\\[-Wstringop-truncation" } */
+}
+
+void stpncpy_str_nowarn_3 (struct C *pc, const char *s)
+{
+  char *d = stpncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str);   /* { dg-bogus "\\\[-Wstringop-truncation" } */
+
+  d[-1] = 0;
+}
+
+void stpncpy_str_nowarn_4 (struct C *pc, const char *s)
+{
+  char *d = stpncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str - 1);   /* { dg-bogus "\\\[-Wstringop-truncation" } */
+
+  *d = 0;
+}
+
+void strncpy_arr_1 (struct C *pc, const char *s)
+{
+  strncpy (pc->b[0].a[0].arr, s, sizeof pc->b[0].a[0].arr);
+  sink (pc->b[0].a[0].arr);
+
+  strncpy (pc->b[0].a[1].arr, s, sizeof pc->b[0].a[1].arr);
+  sink (pc->b[0].a[1].arr);
+
+  strncpy (pc->b[0].a[2].arr, s, sizeof pc->b[0].a[2].arr);
+  sink (pc->b[0].a[2].arr);
+}
+
+void strncpy_str_nowarn_1 (struct C *pc, const char *s)
+{
+  strncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str);   /* { dg-bogus "\\\[-Wstringop-truncation" } */
+
+  pc->b[0].a[0].str[sizeof pc->b[0].a[0].str - 1] = 0;
+}
+
+void strncpy_str_warn_1 (struct C *pc, const char *s)
+{
+  strncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str);   /* { dg-warning "specified bound 3 equals destination size" } */
+
+  pc->b[1].a[0].str[sizeof pc->b[0].a[0].str - 1] = 0;
+}
+
+void strncpy_str_warn_2 (struct C *pc, const char *s)
+{
+  strncpy (pc->b[0].a[0].str, s, sizeof pc->b[0].a[0].str);   /* { dg-warning "specified bound 3 equals destination size" } */
+
+  pc->b[0].a[1].str[sizeof pc->b[0].a[0].str - 1] = 0;
+}