[GHC] #13973: NamedFieldPuns fails for qualified imports if field name is already in scope

[GHC]

#13973: NamedFieldPuns fails for qualified imports if field name is already in
scope
-------------------------------------+-------------------------------------
           Reporter:  sergv          |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Compile-time
  Unknown/Multiple                   |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Hi, I get following error on the program below

 {{{
 Package has never been configured. Configuring with default flags. If this
 fails, please run configure manually.
 Resolving dependencies...
 Configuring test-0.1.0.0...
 Building test-0.1.0.0...
 Preprocessing library test-0.1.0.0...
 [1 of 2] Compiling Record           ( Record.hs, dist/build/Record.o )
 [2 of 2] Compiling Test             ( Test.hs, dist/build/Test.o )

 <no location info>: error:
     ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
         translateConPatVec: lookup

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 The cabal project:
 {{{
 name: test
 version: 0.1.0.0
 cabal-version: >= 1.16
 build-type: Simple

 library
   exposed-modules: Record Test
   default-language: Haskell98
   build-depends: base >= 4.7
 }}}

 The module `Record.hs`:
 {{{#!hs
 module Record (Record(..)) where

 data Record = Record { field1 :: Int, field2 :: Int }
 }}}

 The main module `Test.hs`:
 {{{#!hs
 {-# LANGUAGE NamedFieldPuns #-}

 module Test (foo) where

 import qualified Record as Rec

 -- The culprit
 field2 :: ()
 field2 = ()

 foo :: Rec.Record -> Int
 foo Rec.Record{Rec.field1, field2} = field1 + field2
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13973>
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