TH shadowing bind statement triggers -Wunused-matches

{-# LANGUAGE TemplateHaskell #-}
module Test where

import Language.Haskell.TH

m :: (a -> [b]) -> a -> [b]
m =
  $(newName "x" >>= \x ->
    newName "f" >>= \f ->
    lamE [varP f, varP x]
      (doE [ bindS (varP x) (listE [varE f `appE` varE x])
           , noBindS (varE x)])
   )

The splice generates the following expression:

\f x -> do
  x <- [f x]
  x

and -Wunused-matches complains that x is not used, while both bound occurrences are in fact used (the two uses have different types so that's quite certain).