Overloaded state-monadic function is not specialised

I have a simple typeclass-polymorphic function which fails to specialise. Here is module A which defines the function overloaded:

module A where

import Control.Monad.Trans.State
import Control.Monad

overloaded :: Ord a => a -> a -> State () ()
overloaded x y = do
  () <- get
  when (x <= y) (overloaded y x)

In module B I use overloaded on Ints:

module B where

import A
import Control.Monad.Trans.State

specialised :: Int -> Int -> ()
specialised x y = execState (A.overloaded x y) ()

Unfortunately the generated code is not specialised but passes an Ord dictionary around. It doesn't make any difference if I mark overloaded as INLINEABLE or not.

In the core file, overloaded has been worker-wrapper transformed but the worker is marked INLINEABLE[0] - so I'm not sure why it's not being specialised. Curiously, if I make overloaded be a normal function instead of one in the state monad, or if I replace () <- get with simply get, specialisation goes through fine.

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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