-XRebindableSyntax needs return?

The documentation for -XRebindableSyntax ( https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#rebindable-syntax-and-the-implicit-prelude-import ) reads:

“Do” notation is translated using whatever functions (>>=), (>>), and fail, are in scope (not the Prelude versions). List comprehensions, mdo (The recursive do-notation), and parallel array comprehensions, are unaffected.

The following code fails to compile (also confirmed to fail on GHC 8.0.2):

{-# LANGUAGE RebindableSyntax #-}

module Lib where

import Prelude (IO)

foo :: IO ()
foo = do
  pure ()

It fails with this error:

/home/kel317/z/src/Lib.hs:9:3: error:
    Not in scope: ‘return’
    Perhaps you want to add ‘return’ to the import list
    in the import of ‘Prelude’ (src/Lib.hs:5:1-19).
  |
9 |   pure ()
  |   ^^^^^^^

To my reading, either something funky is going on with the way the do-notation is desugared, or the documentation needs to be corrected.

Trac metadata

Trac field	Value
Version	8.2.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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