Bad error message for malformed GADTs

Compiling the following code:

data Foo a where
   Bar :: a -> a

results in the following error message:

$ ghc-6.8.1 gadt.hs -XGADTs

gadt.hs:5:3:
    Malformed constructor result type: a
    In the result type of a data constructor: a
    In the data type declaration for `Foo'
$ 

It would be nice if the error message mentioned the name of the offending data constructor (Bar in this case) -- since there might be more than one.

Trac metadata

Trac field	Value
Version	6.8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
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Blocking
CC
Operating system	Unknown
Architecture	Unknown