Add test for PR tree-optimization/92879.

gcc/testsuite/ChangeLog:

	PR tree-optimization/92879
	* g++.dg/warn/Warray-bounds-16.C: New test.

gcc/testsuite/g++.dg/warn/Warray-bounds-16.C

@@ -0,0 +1,29 @@
+/* PR tree-optimization/92879 - incorrect warning of __builtin_memset
+   offset is out of the bounds on zero-size allocation and initialization
+   { dg-do compile }
+   { dg-options "-O2 -Wall -fdump-tree-optimized" } */
+
+inline void* operator new (__SIZE_TYPE__, void * v)
+{
+  return v;
+}
+
+struct S
+{
+  int* p;
+  int m;
+
+  S (int i)
+  {
+    m = i;
+    p = (int*) new unsigned char [sizeof (int) * m];
+
+    for (int i = 0; i < m; i++)
+      new (p + i) int ();
+  }
+};
+
+S a (0);
+
+/* Verify the loop has been eliminated.
+   { dg-final { scan-tree-dump-not "goto" "optimized" } } */