#5792: PolyKinds and recompilation causes internal error
--------------------------------+-------------------------------------------
Reporter: reinerp | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler (Type checker)
Version: 7.4.1-rc1 | Keywords:
Os: MacOS X | Architecture: Unknown/Multiple
Failure: Compile-time crash | Testcase:
Blockedby: | Blocking:
Related: |
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Given these two files:
{{{
module A where
-- empty
}}}
and
{{{
{-# LANGUAGE PolyKinds, TypeFamilies, UndecidableInstances #-}
module B where
import A
data T = TT
type family Compare (m :: T) :: Ordering
type instance Compare TT = Compare TT
type Compare' a = Compare a
}}}
We can cause an internal GHC error as follows:
{{{
$ rm *.o *.hi
$ ghc B.hs
[1 of 2] Compiling A ( A.hs, A.o )
[2 of 2] Compiling B ( B.hs, B.o )
$ sleep 1
$ touch B.hs
$ ghc B.hs
[2 of 2] Compiling B ( B.hs, B.o )
B.hs:11:19:
GHC internal error: `Compare' is not in scope during type checking,
but it passed the renamer
tcl_env of environment: [(a9R, AThing k_a9U)]
In the type `Compare a'
In the type synonym declaration for Compare'
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5792>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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