PR c++/80972 - C++17 ICE with attribute packed.

	* call.c (build_over_call): Allow a TARGET_EXPR from reference
	binding.

From-SVN: r249420

gcc/cp/ChangeLog

+2017-06-20  Jason Merrill  <jason@redhat.com>
+
+	PR c++/80972 - C++17 ICE with attribute packed.
+	* call.c (build_over_call): Allow a TARGET_EXPR from reference
+	binding.
+
 2017-06-20  Nathan Sidwell  <nathan@acm.org>
 
 	* cp-tree.h (CPTI_NELTS_IDENTIFIER): Delete.

gcc/cp/call.c

@@ -8025,6 +8025,8 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
 	 subobject.  */
       if (CHECKING_P && cxx_dialect >= cxx1z)
 	gcc_assert (TREE_CODE (arg) != TARGET_EXPR
+		    /* It's from binding the ref parm to a packed field. */
+		    || convs[0]->need_temporary_p
 		    || seen_error ()
 		    /* See unsafe_copy_elision_p.  */
 		    || DECL_BASE_CONSTRUCTOR_P (fn));

gcc/testsuite/g++.dg/ext/packed12.C

+// PR c++/80972
+
+struct A { int i; };
+struct B { A a; } __attribute__((packed));
+
+A a = B().a;