No params in TypeParams for singleton types

Author: fingolfin

src/Serialization/main.jl

@@ -167,12 +167,17 @@ struct TypeParams{T, S}
   type::Type{T}
   params::S
 
-  function TypeParams(T::Type, args::Pair...)
-    return new{T, typeof(args)}(T, args)
+  function TypeParams(T::Type, params)
+    if Base.issingletontype(T)
+      return new{T, Nothing}(T, nothing)
+    else
+      return new{T, typeof(params)}(T, params)
+    end
   end
-  TypeParams(T::Type, obj) = new{T, typeof(obj)}(T, obj)
 end
 
+TypeParams(T::Type, args::Pair...) = TypeParams(T, args)
+
 params(tp::TypeParams) = tp.params
 type(tp::TypeParams) = tp.type