re PR c++/86875 (ICE in tsubst_copy, at cp/pt.c:15478)

	PR c++/86875
	* g++.dg/cpp1y/lambda-generic-86875.C: New test.

From-SVN: r267519

gcc/testsuite/ChangeLog

+2019-01-02  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/86875
+	* g++.dg/cpp1y/lambda-generic-86875.C: New test.
+
 2019-01-02  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/48543

gcc/testsuite/g++.dg/cpp1y/lambda-generic-86875.C

+// PR c++/86875
+// { dg-do compile { target c++14 } }
+
+template <typename _Tp> using decay_t = _Tp;
+template <class Fun> class A {
+  Fun fun_;
+
+public:
+  template <class T> A(T p1) : fun_(p1) {}
+  auto operator()() { fun_(this); }
+};
+
+template <class Fun> auto y_combinator(Fun p1) { return A<decay_t<Fun>>(p1); }
+
+int
+main()
+{
+  const unsigned int w = 1;
+  auto foo = y_combinator([=](auto) { auto i = +w; });
+  foo();
+}