DisambiguateRecordFields with qualified import can cause panic

When I'm using DisambiguateRecordFields with GHC 7.2.1 RC1 (7.2.0.20110728), I encounter panic.

module M where
data S = MkS { x :: Int, y :: Bool }

{-# LANGUAGE DisambiguateRecordFields #-}
module Foo where
import qualified M
notScope (MkS { x = n }) = n

This code causes panic when using GHC 7.2.1 RC1, and GHC 7.3.20110802.

 (snip)
[1 of 2] Compiling M                ( M.hs, interpreted )
[2 of 2] Compiling Foo              ( Test.hs, interpreted )
ghc.exe: panic! (the 'impossible' happened)
  (GHC version 7.3.20110802 for i386-unknown-mingw32):
        find_tycon
    MkS{d 02A}
    []

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

>

This problem is caused by using DisambiguateRecordFields extention. When I remove DisambiguateRecordFields extention from Foo module, GHC doesn't cause panic.

module Foo where
import qualified M
notScope (MkS { x = n }) = n

> :r
[2 of 2] Compiling Foo              ( Test.hs, interpreted )

Test.hs:4:11:
    Not in scope: data constructor `MkS'
    Perhaps you meant `M.MkS' (imported from M)

Test.hs:4:17: `x' is not a (visible) field of constructor `MkS'
Failed, modules loaded: M.
*M>

GHC 7.0.4 doesn't cause panic even though using DisambiguateRecordFields extention.

[1 of 2] Compiling M                ( M.hs, interpreted )
[2 of 2] Compiling Foo              ( Test.hs, interpreted )

Test.hs:4:11: Not in scope: data constructor `MkS'

Test.hs:4:17: `x' is not a (visible) field of constructor `MkS'
Failed, modules loaded: M.

So, I think this problem comes from 5d89565b .

Trac metadata

Trac field	Value
Version	7.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture