id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
2937,"source file that compiled fine fails to recompile after touching it (yes, another one)",rwbarton,simonpj,"I'm using the development snapshot `ghc-6.11.20090107` and ran into a bug very similar to #2888, but I think it is different because I could not reproduce that bug in my version.

The setup is very similar: File `A.hs` contains
{{{
{-# LANGUAGE TypeFamilies #-}
module A where
class Foo a where
  data Bar a :: * -> *
}}}
and file `B.hs` contains
{{{
{-# LANGUAGE TypeFamilies #-}
module B where
import A
instance Foo Int where
  data Bar Int x where
    Baz :: Bar Int String
}}}
Then:
{{{
rwbarton@functor:/tmp/a$ ghc --make B
[1 of 2] Compiling A                ( A.hs, A.o )
[2 of 2] Compiling B                ( B.hs, B.o )
rwbarton@functor:/tmp/a$ touch B.hs
rwbarton@functor:/tmp/a$ ghc --make B
[2 of 2] Compiling B                ( B.hs, B.o )

B.hs:8:2:
    Arguments that do not correspond to a class parameter must be variables
    Instead of a variable, found Int
    In the associated type instance for `Bar'
    In the instance declaration for `Foo Int'
}}}",bug,closed,normal,6.10.2,Compiler,6.11,fixed,,,Unknown/Multiple,Unknown/Multiple,,Unknown,tc245,,,