--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-61.c	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,190 @@
+/* PR middle-end/94940 - spurious -Warray-bounds for a zero length array
+   member of union
+   { dg-do compile }
+   { dg-options "-O2 -Wall" } */
+
+extern int n;
+
+extern union Ua3_a0 {
+  int a3[3];
+  int a2[2];                  // can only alias a3[0 - 2]
+  int a1[1];                  // can alias all of the union
+  int a0[0];                  // ditto
+} ua3_a0;
+
+void test_ua3_ua0_a0 (int i)
+{
+  ua3_a0.a0[0] = 0;           // { dg-bogus "\\\[-Warray-bounds" }
+  ua3_a0.a0[1] = 0;           // { dg-bogus "\\\[-Warray-bounds" }
+  ua3_a0.a0[2] = 0;           // { dg-bogus "\\\[-Warray-bounds" }
+  ua3_a0.a0[3] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+  ua3_a0.a0[4] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+  ua3_a0.a0[i] = 0;           // { dg-bogus "\\\[-Warray-bounds" }
+
+  if (i < __LINE__)
+    i = 5;
+  ua3_a0.a0[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+
+  if (i > -1)
+    i = -1;
+  ua3_a0.a0[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+}
+
+void test_ua3_ua0_a1 (int i)
+{
+  /* Abusing one-element array members the same way as those of
+     length zero is discouraged but so far acceted without warnings.
+     This should change at some point.  */
+
+  ua3_a0.a1[0] = 0;
+  ua3_a0.a1[1] = 0;
+  ua3_a0.a1[2] = 0;
+  ua3_a0.a1[3] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+  ua3_a0.a1[i] = 0;
+
+  if (i > -1)
+    i = -1;
+  ua3_a0.a1[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+
+  if (i < 7)
+    i = 7;
+  ua3_a0.a1[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+}
+
+void test_ua3_ua0_a2 (int i)
+{
+  ua3_a0.a2[0] = 0;
+  ua3_a0.a2[1] = 0;
+  ua3_a0.a2[2] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+  ua3_a0.a2[i] = 0;
+
+  if (i < __LINE__)
+    i = __LINE__;
+  ua3_a0.a2[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+
+  if (i > -1)
+    i = -1;
+  ua3_a0.a2[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+}
+
+
+extern union Ua2_a3 {
+  int a2[2];                  // can only alias a3[0 - 1]
+  int a3[3];
+} ua2_a3;
+
+void test_ua2_ua3 (int i)
+{
+  ua2_a3.a2[0] = 0;           // { dg-bogus "\\\[-Warray-bounds" }
+  ua2_a3.a2[1] = 0;           // { dg-bogus "\\\[-Warray-bounds" }
+  ua2_a3.a2[2] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+  ua2_a3.a2[i] = 0;
+
+  if (i < __LINE__)
+    i = __LINE__;
+  ua2_a3.a2[i] = 0;           // { dg-warning "\\\[-Warray-bounds" }
+}
+
+
+extern struct SUa2_a0 {
+  union Ua2_a0 {
+    int a2[2];
+    int a0[0];
+  } u;
+} sua2_a0;
+
+void test_sua2_sua0 (int i)
+{
+  n += sua2_a0.u.a0[0];
+  n += sua2_a0.u.a0[1];
+  n += sua2_a0.u.a0[2];       // { dg-warning "\\\[-Warray-bounds" }
+  n += sua2_a0.u.a0[i];
+
+  if (i < __LINE__)
+    i = __LINE__;
+  n += sua2_a0.u.a0[i];       // { dg-warning "\\\[-Warray-bounds" }
+}
+
+void test_sua2_sua0_ptr (int i)
+{
+  union Ua2_a0 *p = &sua2_a0.u;
+
+  n += p->a0[0];
+  n += p->a0[1];
+  n += p->a0[2];              // { dg-warning "\\\[-Warray-bounds" }
+  n += p->a0[i];
+}
+
+
+extern struct SUSa3_a0 {
+  union USa3_a0 {
+    struct {
+      int a3[3];
+    } s;
+    int a2[2];                // can alias s.a3[0 - 2]
+    int a1[1];                // can alias s.a3[0 - 2]
+    int a0[0];                // can alias s.a3[0]
+  } u;
+} susa3_ua0;
+
+void test_susa3_sua0 (int i, int j)
+{
+  n += susa3_ua0.u.a0[0];
+  n += susa3_ua0.u.a0[1];
+  n += susa3_ua0.u.a0[2];
+  n += susa3_ua0.u.a0[3];     // { dg-warning "\\\[-Warray-bounds" }
+}
+
+void test_susa3_sua0_ptr (int i, int j)
+{
+  union USa3_a0 *p = &susa3_ua0.u;
+  n += p->a0[0];
+  n += p->a0[1];
+  n += p->a0[2];
+  n += p->a0[3];              // { dg-warning "\\\[-Warray-bounds" }
+}
+
+void test_susa3_sua1 (int i)
+{
+  n += susa3_ua0.u.a1[0];
+  n += susa3_ua0.u.a1[1];
+  n += susa3_ua0.u.a1[2];
+  n += susa3_ua0.u.a1[3];     // { dg-warning "\\\[-Warray-bounds" }
+
+  if (i < __LINE__)
+    i = __LINE__;
+  n += susa3_ua0.u.a1[i];     // { dg-warning "\\\[-Warray-bounds" }
+}
+
+void test_susa3_sua2 (void)
+{
+  n += susa3_ua0.u.a2[0];
+  n += susa3_ua0.u.a2[1];
+  n += susa3_ua0.u.a2[2];     // { dg-warning "\\\[-Warray-bounds" }
+  n += susa3_ua0.u.a2[3];     // { dg-warning "\\\[-Warray-bounds" }
+}
+
+
+extern struct {
+  union {
+    struct {
+      int a3[3];
+    } s1;
+    struct {
+      int a0[0];
+    } s2;
+  } u;
+} susa3_usa0;
+
+void test_susi3_susi0 (int i)
+{
+  n += susa3_usa0.u.s2.a0[0];
+  n += susa3_usa0.u.s2.a0[1];
+  n += susa3_usa0.u.s2.a0[2];
+  n += susa3_usa0.u.s2.a0[3]; // { dg-warning "\\\[-Warray-bounds" }
+  n += susa3_usa0.u.s2.a0[i];
+
+  if (i < __LINE__)
+    i = __LINE__;
+  n += susa3_usa0.u.s2.a0[i]; // { dg-warning "\\\[-Warray-bounds" }
+}