#5691: Crash: strange interaction of ScopedTypeVariables extension with type class name resolution ------------------------------------------+--------------------------------- Reporter: dominiquedevriese | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.0.4 Resolution: fixed | Keywords: ScopedTypeVariables, type classes Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: Compile-time crash | Difficulty: Unknown Testcase: typecheck/should_fail/T5691 | Blockedby: Blocking: | Related: ------------------------------------------+--------------------------------- Changes (by simonpj):
* status: new => closed * difficulty: => Unknown * resolution: => fixed * testcase: => typecheck/should_fail/T5691 Comment: Interesting! Indeed with 7.0.3 I get {{{ simonpj@cam-04-unx:~/tmp$ ghc-7.0.3 -c T5691.hs -dcore-lint *** Core Lint errors : in result of Desugar *** <no location info>: In the coercion `co_alI' co_alI is out of scope *** Offending Program *** ...snip... }}} But with HEAD I get {{{ T5691.hs:15:24: Couldn't match type `p' with `PrintRuleInterp' Expected type: PrintRuleInterp a Actual type: p a In the first argument of `printRule_', namely `f' In the second argument of `($)', namely `printRule_ f' In the expression: MkPRI $ printRule_ f T5691.hs:24:10: No instance for (Monad RecDecParser) arising from the superclasses of an instance declaration Possible fix: add an instance declaration for (Monad RecDecParser) In the instance declaration for `MonadPlus RecDecParser' }}} both of which are correct. Rather than investigate further, I'll mark this as fixed, but I'll add it to the test suite. Thanks simon -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5691#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler _______________________________________________ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs