--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/init/string4.C	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,60 @@
+// PR tree-optimization/71625 - missing strlen optimization on different
+// array initialization style
+
+// Verify that zero-length array initialization results in the expected
+// array sizes and in the expected diagnostics.  See init-string-3.c
+// for the corresponding C test.
+
+// { dg-do compile }
+// { dg-options "-Wall -Wno-unused-local-typedefs -fpermissive" }
+
+#define A(expr) typedef char A[-1 + 2 * !!(expr)];
+
+const char a[] = { };
+
+A (sizeof a == 0);
+
+
+const char b[0] = { };
+
+A (sizeof b == 0);
+
+// Also verify that the error is "too many initializers for
+// 'const char [0]'" and not "initializer-string is too long."
+const char c[0] = { 1 };      // { dg-error "too many initializers for .const char \\\[0]" }
+
+A (sizeof c == 0);
+
+
+void test_auto_empty (void)
+{
+  const char a[] = { };
+
+  A (sizeof a == 0);
+}
+
+void test_auto_zero_length (void)
+{
+  const char a[0] = { };
+
+  A (sizeof a == 0);
+
+  const char b[0] = { 0 };    // { dg-error "too many initializers" }
+
+  A (sizeof b == 0);
+
+  const char c[0] = "";       // { dg-warning "too long" }
+
+  A (sizeof c == 0);
+}
+
+
+void test_compound_zero_length (void)
+{
+  A (sizeof (const char[]){ } == 0);
+  A (sizeof (const char[0]){ } == 0);
+  A (sizeof (const char[0]){ 0 } == 0);    // { dg-error "too many" }
+  A (sizeof (const char[0]){ 1 } == 0);    // { dg-error "too many" }
+  A (sizeof (const char[0]){ "" } == 0);   // { dg-warning "too long" }
+  A (sizeof (const char[0]){ "1" } == 0);  // { dg-warning "too long" }
+}