Variables in patterns made with QuasiQuotes sometimes don't get bound

In GHCi 8.0.2

>>> import Language.Haskell.TH
>>> import Language.Haskell.TH.Quote
>>> :set -XQuasiQuotes
>>> quoter = QuasiQuoter { quotePat = varP . mkName }
>>> [quoter|x|] = 1
>>> x
error: Variable not in scope: x

I think "x" ought to be 1.

Previous versions of GHCi don't let me be so free about defining and using quasiquotes, so here is a minimal example with modules:

-- In QQ.hs
module QQ where

import Language.Haskell.TH
import Language.Haskell.TH.Quote

quoter :: QuasiQuoter
quoter = QuasiQuoter { quotePat = varP . mkName }

and

-- In Main1.hs
module Main1 where

import QQ

[quoter|x|] = 1

main = print x

With GHC 7.10.3 this compiles (and prints "1" when run), but in GHC 8.0.2 this complains "x" is not in scope. The same problem manifests itself when the pattern quasi quote is used in a "let" binding.

Peculiarly, this appears not to affect cases where the pattern is a function argument. The following compiles and runs (printing "1") on both 7.10.3 and 8.0.2.

-- In Main2.hs
module Main2 where

import QQ

f [quoter|x|] = x

main = print (f 1)

I understand there were some changes around splices and declaration groups (which presumably are part of why GHCi plays with quasi quotes), so I'm not sure this is really a bug!

Trac metadata

Trac field	Value
Version	8.0.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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