PR c++/79640 - infinite recursion with generic lambda.

	* pt.c (tsubst_copy) [VAR_DECL]: Register the dummy instantiation
	before substituting its initializer.

From-SVN: r246289

gcc/cp/ChangeLog

+2017-03-20  Jason Merrill  <jason@redhat.com>
+
+	PR c++/79640 - infinite recursion with generic lambda.
+	* pt.c (tsubst_copy) [VAR_DECL]: Register the dummy instantiation
+	before substituting its initializer.
+
 2017-03-20  Marek Polacek  <polacek@redhat.com>
 	    Paolo Carlini  <paolo.carlini@oracle.com>
 

gcc/cp/pt.c

@@ -14581,6 +14581,9 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 		     local static or constant.  Building a new VAR_DECL
 		     should be OK in all those cases.  */
 		  r = tsubst_decl (t, args, complain);
+		  if (local_specializations)
+		    /* Avoid infinite recursion (79640).  */
+		    register_local_specialization (r, t);
 		  if (decl_maybe_constant_var_p (r))
 		    {
 		      /* We can't call cp_finish_decl, so handle the

gcc/testsuite/g++.dg/cpp1y/lambda-generic-const3.C

+// PR c++/79640
+// { dg-do compile { target c++14 } }
+
+template<typename F> void foo(F f)
+{
+  f(1);
+}
+
+template<int> void bar()
+{
+  const int i = i;
+  foo([] (auto) { sizeof(i); });
+}
+
+void baz() { bar<1>(); }