--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/opt/pr83187.C	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,32 @@
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-O1 -Wno-pedantic" }
+// PR c++/83187 ICE in get_alias_set due to canonical type confusion.
+
+extern "C" {
+  double cos (double);
+  double sin (double);
+}
+
+template <typename> class COMPLEX;
+
+template <>
+struct COMPLEX<double>
+{
+  COMPLEX(double r, double i);
+
+  __complex__ mem;
+};
+
+COMPLEX<double>::COMPLEX (double r, double i)
+  : mem {r, i} {}
+
+typedef double dbl_t;
+
+dbl_t var;
+
+void foo (COMPLEX<double> *ptr)
+{
+  const dbl_t unused = var;
+
+  *ptr = COMPLEX<double> (cos (var), sin (var));
+}