re PR go/67968 (go1: internal compiler error: in write_specific_type_functions,…

re PR go/67968 (go1: internal compiler error: in write_specific_type_functions, at go/gofrontend/types.cc:1812)

	PR go/67968
    compiler: Traverse types of call expressions.
    
    https://gcc.gnu.org/PR67968 provides a test case that causes a gccgo
    crash on valid code.  The compiler failed to build the hash and equality
    functions required for a type descriptor.  The descriptor is for an
    unnamed type that is being returned by a function imported from a
    different package.  The unnamed type is being implicitly converted to an
    interface type by a return statement.  The fix is to ensure that the
    type of a call expression is always traversed.
    
    Test case sent out for the master testsuite as
    https://golang.org/cl/16532 .

From-SVN: r229642

gcc/go/gofrontend/MERGE

-1c1f226662a6c84eae83f8aaec3d4503e70be843
+65ff1d5fb581717229e5c02796d719671a1e8628
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/expressions.cc

@@ -8608,6 +8608,16 @@ Builtin_call_expression::do_export(Export* exp) const
 int
 Call_expression::do_traverse(Traverse* traverse)
 {
+  // If we are calling a function in a different package that returns
+  // an unnamed type, this may be the only chance we get to traverse
+  // that type.  We don't traverse this->type_ because it may be a
+  // Call_multiple_result_type that will just lead back here.
+  if (this->type_ != NULL && !this->type_->is_error_type())
+    {
+      Function_type *fntype = this->get_function_type();
+      if (fntype != NULL && Type::traverse(fntype, traverse) == TRAVERSE_EXIT)
+	return TRAVERSE_EXIT;
+    }
   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
     return TRAVERSE_EXIT;
   if (this->args_ != NULL)