[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
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by sergv):

 * failure:  Compile-time crash or panic => Poor/confusing error message


Old description:

> 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
> }}}

New description:

 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
 }}}

 The program is invalid - named field `field2` should be written as
 `Rec.field2`, however I'd expect more informative error message instead of
 panic.

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13973#comment:1>
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