Record-like GADTs with repeated fields (of same type) rejected

I came across a curious bug with record-like GADTs and repeated fields. Consider following code:

{-# LANGUAGE GADTs #-}

data Foo p where
  Bar :: { quux' :: Bool } -> Foo Char
  Baz :: { quux'' :: Bool } -> Foo Int

quux :: Foo p -> Bool
quux (Bar q) = q
quux (Baz q) = q

quuxSetter :: Foo p -> Bool -> Foo p
quuxSetter old@Bar{} q = old{quux' = q}
quuxSetter old@Baz{} q = old{quux'' = q}

This compiles and all is fine. *But* GHC is supposed to create the nice quux and quuxSetter accessors for me, right?

So, let's try:

data Foo p where
  Bar :: { quux :: Bool } -> Foo Char
  Baz :: { quux :: Bool } -> Foo Int

It does not compile! Instead I get:

T12159.hs:3:1: error:
      Constructors Bar and Baz have a common field  quux ,
        but have different result types
      In the data type declaration for  Foo 
Failed, modules loaded: none.

This is not very polite :-) It should simply create the accessors like I did above. It obviously can be done!

Testcase is attached.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture