re PR c++/85068 (ICE with invalid covariant return type hierarchy)

	PR c++/85068
	* class.c (update_vtable_entry_for_fn): Don't ICE if base_binfo
	is NULL.  Assert if thunk_binfo is NULL then errorcount is non-zero.

	* g++.dg/inherit/covariant22.C: New test.

From-SVN: r258873

gcc/cp/ChangeLog

+2018-03-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/85068
+	* class.c (update_vtable_entry_for_fn): Don't ICE if base_binfo
+	is NULL.  Assert if thunk_binfo is NULL then errorcount is non-zero.
+
 2018-03-27  Paolo Carlini  <paolo.carlini@oracle.com>
 	    Jason Merrill  <jason@redhat.com>
 

gcc/cp/class.c

@@ -2479,19 +2479,20 @@ update_vtable_entry_for_fn (tree t, tree binfo, tree fn, tree* virtuals,
 	     order.  Of course it is lame that we have to repeat the
 	     search here anyway -- we should really be caching pieces
 	     of the vtable and avoiding this repeated work.  */
-	  tree thunk_binfo, base_binfo;
+	  tree thunk_binfo = NULL_TREE;
+	  tree base_binfo = TYPE_BINFO (base_return);
 
 	  /* Find the base binfo within the overriding function's
 	     return type.  We will always find a thunk_binfo, except
 	     when the covariancy is invalid (which we will have
 	     already diagnosed).  */
-	  for (base_binfo = TYPE_BINFO (base_return),
-	       thunk_binfo = TYPE_BINFO (over_return);
-	       thunk_binfo;
-	       thunk_binfo = TREE_CHAIN (thunk_binfo))
-	    if (SAME_BINFO_TYPE_P (BINFO_TYPE (thunk_binfo),
-				   BINFO_TYPE (base_binfo)))
-	      break;
+	  if (base_binfo)
+	    for (thunk_binfo = TYPE_BINFO (over_return); thunk_binfo;
+		 thunk_binfo = TREE_CHAIN (thunk_binfo))
+	      if (SAME_BINFO_TYPE_P (BINFO_TYPE (thunk_binfo),
+				     BINFO_TYPE (base_binfo)))
+		break;
+	  gcc_assert (thunk_binfo || errorcount);
 
 	  /* See if virtual inheritance is involved.  */
 	  for (virtual_offset = thunk_binfo;

gcc/testsuite/ChangeLog

+2018-03-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/85068
+	* g++.dg/inherit/covariant22.C: New test.
+
 2018-03-27  Richard Biener  <rguenther@suse.de>
 
 	PR testsuite/84004

gcc/testsuite/g++.dg/inherit/covariant22.C

+// PR c++/85068
+// { dg-do compile }
+
+struct A;
+
+struct B
+{
+  virtual A *foo ();	// { dg-error "overriding" }
+};
+
+struct C : virtual B
+{
+  virtual C *foo ();	// { dg-error "invalid covariant return type for" }
+};
+
+struct D : C
+{
+  virtual C *foo ();
+};