Pattern matching duplicated record fields

GHC panic during compiling pattern matching with duplicated record fields. The following is a short example.

Main module:

module Lib
    ( someFunc
    ) where

import F1
import qualified F2

r :: F2.T2
r = F2.T2 {
  F2.foo = "ok"
}

someFunc :: IO ()
someFunc = case r of
  F2.T2{ foo = a } -> putStrLn a

The first submodule:

module F1
    ( T1(..)
    ) where

newtype T1 = T1 {
  foo :: String
}

The second submodule:

module F2
    ( T2(..)
    ) where

newtype T2 = T2 {
  foo :: String
}

GHC compiles the modules successfully if uses DuplicateRecordFields.

The modules may be not correct without DuplicateRecordFields. But GHC should show an error message other than panic.

Trac metadata

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