re PR c++/85209 (ICE with lambda and structured binding)

	PR c++/85209
	* pt.c (tsubst_decomp_names): Don't fail or ICE if DECL_CHAIN (decl3)
	is not prev, if prev == decl.

	* g++.dg/cpp1z/decomp39.C: New test.
	* g++.dg/cpp1z/decomp40.C: New test.

From-SVN: r259156

gcc/cp/ChangeLog

 2018-04-05  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/85209
+	* pt.c (tsubst_decomp_names): Don't fail or ICE if DECL_CHAIN (decl3)
+	is not prev, if prev == decl.
+
 	PR c++/85208
 	* decl.c (start_decl): For DECL_DECOMPOSITION_P decls, don't call
 	maybe_apply_pragma_weak here...

gcc/cp/pt.c

@@ -16239,7 +16239,8 @@ tsubst_decomp_names (tree decl, tree pattern_decl, tree args,
       if (error_operand_p (decl3))
 	decl = error_mark_node;
       else if (decl != error_mark_node
-	       && DECL_CHAIN (decl3) != prev)
+	       && DECL_CHAIN (decl3) != prev
+	       && decl != prev)
 	{
 	  gcc_assert (errorcount);
 	  decl = error_mark_node;

gcc/testsuite/ChangeLog

 2018-04-05  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/85209
+	* g++.dg/cpp1z/decomp39.C: New test.
+	* g++.dg/cpp1z/decomp40.C: New test.
+
 	PR c++/85208
 	* g++.dg/cpp1z/decomp41.C: New test.
 

gcc/testsuite/g++.dg/cpp1z/decomp39.C

+// PR c++/85209
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+template <int>
+void
+foo ()
+{
+  auto [a] = []{};	// { dg-error "cannot decompose lambda closure type" }
+}			// { dg-warning "structured bindings only available with" "" { target c++14_down } .-1 }
+
+void
+bar ()
+{
+  foo<0> ();
+}

gcc/testsuite/g++.dg/cpp1z/decomp40.C

+// PR c++/85209
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct S { int a; } s;
+
+template <int>
+void
+foo ()
+{
+  auto [a] = []{ return s; } ();	// { dg-warning "structured bindings only available with" "" { target c++14_down } }
+};
+
+void
+bar ()
+{
+  foo<0> ();
+}