GitLab

{-# language TemplateHaskell #-}
{-# language DuplicateRecordFields #-}
module Lib where
import Language.Haskell.TH
import Language.Haskell.TH.Syntax

data A = A {x :: Int, y :: String}
a = A 3 "test"
test = $([e|case a of A {x = b} -> b|])

Without DuplicateRecordFields it compiles correctly so test = 3 but with DuplicateRecordFields enabled it gives:

     • Illegal variable name: ‘$sel:x:A’
      When splicing a TH expression:
        case Lib.a of
    (Lib.A {Lib.$sel:x:A = b_0}) -> b_0
    • In the untyped splice: $([| case a of { A {x = b} -> b } |])

Additionally, there doesn't seem to be a workaround for munging the name manually, since the $sel:x:A name is the one actually in scope, there is no A.x like there would be normally, even when the label is not a duplicate.

Is there a way to get around this? Ex: by changing the binding name somehow manually?

Trac metadata

Trac field	Value
Version	8.2.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture