--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/Wzero-length-array-bounds.c	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,88 @@
+/* PR middle-end/91647 - missing -Warray-bounds accessing a zero-length array
+   of a declared object
+   Test to exercise -Wzero-length-bounds.
+   { dg-do compile }
+   { dg-options "-O2 -Wall" } */
+
+void sink (void*);
+
+struct X { int a[0]; int b, c; };
+
+extern struct X x;
+
+void bad (int i, int j)
+{
+  x.a[0] = 0;           // { dg-warning "\\\[-Wzero-length-bounds" }
+  x.a[1] = 1;           // { dg-warning "\\\[-Wzero-length-bounds" }
+  x.a[2] = 2;           // { dg-warning "\\\[-Warray-bounds" }
+
+  x.a[i] = 3;           // { dg-warning "\\\[-Wzero-length-bounds" }
+  x.a[j] = 4;           // { dg-warning "array subscript 'j' is outside the bounds of an interior zero-length array" }
+}
+
+void access_by_reference (struct X *p, int i)
+{
+  p->a[0] = 0;          // { dg-warning "\\\[-Wzero-length-bounds" }
+  p->a[1] = 0;          // { dg-warning "\\\[-Wzero-length-bounds" }
+  p->a[2] = 0;          // { dg-warning "\\\[-Wzero-length-bounds" }
+  p->a[i] = 0;          // { dg-warning "\\\[-Wzero-length-bounds" }
+}
+
+
+extern struct X a[2];
+
+void access_to_array (int i)
+{
+  a[0].a[0] = 0;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  a[0].a[1] = 1;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  /* Accesses to a subsequent element of the enclosing array seem like
+     a more sever problem than those to the next member of the same
+     struct and so might perhaps be better diagnosed by -Warray-bounds.
+     Then again, code that does this sort of crap might as well get what
+     it deserves if it disables -Wzero-length-bounds.  */
+  a[0].a[2] = 2;        // { dg-warning "\\\[-Wzero-length-bounds" }
+
+  a[0].a[i] = 3;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  sink (a);
+
+  a[1].a[0] = 4;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  a[1].a[1] = 5;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  a[1].a[2] = 6;        // { dg-warning "\\\[-Warray-bounds" }
+
+  a[1].a[i] = 7;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  sink (a);
+
+  a[i].a[0] = 8;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  a[i].a[1] = 9;        // { dg-warning "\\\[-Wzero-length-bounds" }
+  a[i].a[2] = 0;        // { dg-warning "\\\[-Wzero-length-bounds" }
+}
+
+
+struct Y
+{
+  struct X a[2], b;
+  int c;
+};
+
+extern struct Y y;
+
+void access_to_member (int i)
+{
+  y.a[0].a[0] = 0;      // { dg-warning "\\\[-Wzero-length-bounds" }
+  y.a[0].a[1] = 0;      // { dg-warning "\\\[-Wzero-length-bounds" }
+  y.a[0].a[2] = 0;      // { dg-warning "\\\[-Wzero-length-bounds" }
+  sink (a);
+
+  y.a[1].a[0] = 0;      // { dg-warning "\\\[-Wzero-length-bounds" }
+  y.a[1].a[1] = 0;      // { dg-warning "\\\[-Wzero-length-bounds" }
+  /* Similar to the array case above, accesses to a subsequent member
+     of the "parent" struct seem like a more severe problem than those
+     to the next member of the same struct.  */
+  y.a[1].a[2] = 0;      // { dg-warning "\\\[-Wzero-length-bounds" }
+  sink (a);
+
+  y.b.a[0] = 0;         // { dg-warning "\\\[-Wzero-length-bounds" }
+  y.b.a[1] = 0;         // { dg-warning "\\\[-Wzero-length-bounds" }
+  y.b.a[2] = 0;         // { dg-warning "\\\[-Wzero-length-bounds" }
+  y.b.a[3] = 0;         // { dg-warning "\\\[-Warray-bounds" }
+}