Template Haskell thinks an unboxed tuple name is illegal to splice in

{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE UnboxedTuples #-}
module Bug where

import Language.Haskell.TH.Lib
import Language.Haskell.TH.Syntax

$(do let ubxTup = conT (unboxedTupleTypeName 2) `appT` conT ''Int
                                                `appT` conT ''Int
     x <- newName "x"
     y <- newName "y"

     [d| f :: $(ubxTup) -> $(ubxTup)
         f $(conP (unboxedTupleDataName 2) [varP x, varP y])
             = $(conE (unboxedTupleDataName 2) `appE` varE x
                                               `appE` varE y)
      |])

$ /opt/ghc/8.0.1/bin/ghc Bug.hs
[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:8:3: error:
    Illegal type constructor or class name: ‘(#,#)’
    When splicing a TH declaration:
      f_0 :: GHC.Tuple.(#,#) GHC.Types.Int GHC.Types.Int ->
       GHC.Tuple.(#,#) GHC.Types.Int GHC.Types.Int

Patch coming soon.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Template Haskell
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