#5881: Type synonyms of promoted types break across library boundaries?
------------------------------+---------------------------------------------
Reporter: bjornbm | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.4.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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1. Build a library/package consisting of the following module:
{{{
{-# LANGUAGE DataKinds #-}
module One where
data K = T
type T' = T
}}}
2. Compile/interpret the following:
{{{
import One (T')
type DOne = T'
}}}
3. GHC 7.4.1 says:
{{{
[1 of 1] Compiling Main ( Two.hs, interpreted )
ghc: panic! (the 'impossible' happened)
(GHC version 7.4.1 for x86_64-apple-darwin):
tyThingTyCon Data constructor `tyThingTyCon-0.1:One.T{d r9H}'
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
It seems that GHC has problems with type synonyms for promoted types
(DataKinds) loaded from another package. If the panicking code is loaded
from the directory containing One.hs (i.e. One is compiled/interpreted at
the same time) there is no panic.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5881>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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