DimensionTag TODO declare_same_as outdated size_placeholder assign

Author: albertz

returnn/tf/util/data.py

@@ -465,6 +465,7 @@ def declare_same_as(self, other):
     # maybe we can overtake the size_placeholder now.
     if self.same_as.dyn_size is not None and self.src_data:
       assert isinstance(self.src_axis, int)
+      # TODO Is this still needed? also looks wrong
       # Maybe it changed in the meanwhile, so check.
       if self.src_data.get_dim_tag(self.src_axis).description == self.description:
         self.src_data.size_placeholder[