Hi!
Most of the spots in tsubst_baselink that actually access baselink after
it has been assigned lookup_fnfields () test that it is a BASELINK_P, except
one - the BASELINK_OPTYPE update. lookup_fnfields can return
error_mark_node though, perhaps something else too. The patch just follows
what the surrounding code does.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2016-07-11 Jakub Jelinek <ja...@redhat.com>
PR c++/71826
* pt.c (tsubst_baselink): Only set BASELINK_OPTYPE for BASELINK_P.
* g++.dg/template/pr71826.C: New test.
--- gcc/cp/pt.c.jj 2016-07-11 11:14:28.000000000 +0200
+++ gcc/cp/pt.c 2016-07-11 12:30:45.939554745 +0200
@@ -13734,7 +13734,8 @@ tsubst_baselink (tree baselink, tree obj
BASELINK_FUNCTIONS (baselink),
template_args);
/* Update the conversion operator type. */
- BASELINK_OPTYPE (baselink) = optype;
+ if (BASELINK_P (baselink))
+ BASELINK_OPTYPE (baselink) = optype;
if (!object_type)
object_type = current_class_type;
--- gcc/testsuite/g++.dg/template/pr71826.C.jj 2016-07-11 12:34:51.406568756
+0200
+++ gcc/testsuite/g++.dg/template/pr71826.C 2016-07-11 12:33:35.000000000
+0200
@@ -0,0 +1,17 @@
+// PR c++/71826
+// { dg-do compile }
+
+template <class> struct A { int i; }; // { dg-message "note" }
+struct B { void i () {} }; // { dg-message "note" }
+template <class T> struct C : A <T>, B
+{
+ void f () { i (); } // { dg-error "is ambiguous" }
+};
+
+int
+main ()
+{
+ C <int> c;
+ c.f ();
+ return 0;
+}
Jakub
