#9032: Panic with self-import -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Template | Version: 7.8.2 Haskell | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: Compile- | Related Tickets: #1012 time crash | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * component: Compiler => Template Haskell * milestone: => 7.10.1 Old description:
I've run into GHC panic with this code:
{{{ {-# OPTIONS_GHC -fno-warn-unused-imports #-}
module Singletons.Star where
import Data.Singletons.Prelude import Data.Singletons.Decide import Data.Singletons.CustomStar import Singletons.Nat import Singletons.Star -- <------- HERE
data Vec :: * -> Nat -> * where VNil :: Vec a Zero VCons :: a -> Vec a n -> Vec a (Succ n)
$(singletonStar [''Nat, ''Int, ''String, ''Maybe, ''Vec]) }}}
This is a test in `singletons` package that leads to a panic when run:
{{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64-unknown-linux): tcIfaceGlobal (local): not found: singletons-1.0:Singletons.Star.TFCo:R:DemoteRep*KProxy{tc r0} []
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}}
I was unable to minimize the test case. Reproducing requires following steps:
1. Installing latest th-desugar library from github:
{{{ git clone https://github.com/goldfirere/th-desugar.git cd th-desugar cabal install }}}
2. Getting latest development version of singletons:
{{{ git clone https://github.com/goldfirere/singletons cd singletons git checkout 56734c2bda721cb9a6a3021b901e3b29d6564f0c make tests }}}
All should go well. Now you need to edit file `tests/compile-and- dump/Singletons/Star.hs` and uncomment `import Singletons.Star` line. It should be possible to reproduce the bug with:
{{{ cd tests/compile-and-dump/ghc -package-name singletons-1.0 Singletons/Star.hs -i../../dist/build -c -XTemplateHaskell }}}
It's important to run `make tests` first so that all interface files required by `Star.hs` are in place.
New description: A test in the `singletons` package leads to a panic when run: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64-unknown-linux): tcIfaceGlobal (local): not found: singletons-1.0:Singletons.Star.TFCo:R:DemoteRep*KProxy{tc r0} [] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Edit: see comment:1 for a testcase. -- Comment: Still present in 7.9. I have cleaned up the description a bit. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9032#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler