--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1z/decomp38.C	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,47 @@
+// { dg-do compile { target c++17 } }
+
+class X
+{
+   int a, b;
+   void f()
+   {
+     auto[x,y] = *this;
+   }
+};
+
+class X2
+{
+   int a, b;
+   void f(X2& other)
+   {
+     auto[x,y] = other;
+   }
+};
+
+struct X3
+{
+  friend void foo();
+private:
+  int a;
+};
+
+void foo()
+{
+  X3 x;
+  auto [a] = x;
+}
+
+struct X4
+{
+  int a;
+};
+
+struct X5 : private X4
+{
+  friend void foo2();
+};
+
+void foo2() {
+  X5 x;
+  auto [a] = x;
+}