[Bug c++/105425] [12/13 Regression] ambiguous template instantiation with hana::when

[ppalka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105425

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot 
gnu.org

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Untested fix:

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 3cf1d7af8d2..cf24d482488 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -24276,7 +24276,8 @@ unify (tree tparms, tree targs, tree parm, tree arg,
int strict,
            }
        }

-      if (!TREE_TYPE (arg))
+      if (!TREE_TYPE (arg)
+         || TREE_CODE (TREE_TYPE (arg)) == DEPENDENT_OPERATOR_TYPE)
        /* Template-parameter dependent expression.  Just accept it for now.
           It will later be processed in convert_template_argument.  */
        ;