PR c++/84520 - ICE with generic lambda in NSDMI.

	* lambda.c (lambda_expr_this_capture): Don't look for fake NSDMI
	'this' in a generic lambda instantiation.

From-SVN: r258021

gcc/cp/ChangeLog

 2018-02-26  Jason Merrill  <jason@redhat.com>
 
+	PR c++/84520 - ICE with generic lambda in NSDMI.
+	* lambda.c (lambda_expr_this_capture): Don't look for fake NSDMI
+	'this' in a generic lambda instantiation.
+
 	PR c++/84559 - ICE with constexpr VLA.
 	* constexpr.c (ensure_literal_type_for_constexpr_object): Check
 	for constexpr variable with VLA type.

gcc/cp/lambda.c

@@ -758,11 +758,14 @@ lambda_expr_this_capture (tree lambda, bool add_capture_p)
                                     lambda_stack);
 
 	  if (LAMBDA_EXPR_EXTRA_SCOPE (tlambda)
+	      && !COMPLETE_TYPE_P (LAMBDA_EXPR_CLOSURE (tlambda))
 	      && TREE_CODE (LAMBDA_EXPR_EXTRA_SCOPE (tlambda)) == FIELD_DECL)
 	    {
 	      /* In an NSDMI, we don't have a function to look up the decl in,
 		 but the fake 'this' pointer that we're using for parsing is
-		 in scope_chain.  */
+		 in scope_chain.  But if the closure is already complete, we're
+	         in an instantiation of a generic lambda, and the fake 'this'
+	         is gone.  */
 	      init = scope_chain->x_current_class_ptr;
 	      gcc_checking_assert
 		(init && (TREE_TYPE (TREE_TYPE (init))

gcc/testsuite/g++.dg/cpp1y/lambda-generic-nsdmi1.C

+// PR c++/84520
+// { dg-do compile { target c++14 } }
+
+struct A
+{
+  static void foo(int);
+  void (*f)(int) = [](auto i) { foo(i); };
+};