Re: [GHC] #5515: panic! (the 'impossible' happened) with evil self-referential instance

2011-09-30 Thread GHC 
#5515: panic! (the 'impossible' happened) with evil self-referential instance
--+-
  Reporter:  andersk  |  Owner: 
 
  Type:  bug  | Status:  closed 
 
  Priority:  normal   |  Milestone: 
 
 Component:  Compiler |Version:  7.3
 
Resolution:  fixed|   Keywords: 
 
  Testcase:  indexed-types/should_fail/T5515  |  Blockedby: 
 
Difficulty:   | Os:  
Unknown/Multiple
  Blocking:   |   Architecture:  
Unknown/Multiple
   Failure:  Compile-time crash   |  
--+-
Changes (by simonpj):

  * status:  new = closed
  * testcase:  = indexed-types/should_fail/T5515
  * resolution:  = fixed


Comment:

 Thanks very much for the report.  Fixed!

-- 
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/5515#comment:2
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Re: [GHC] #5515: panic! (the 'impossible' happened) with evil self-referential instance

2011-09-29 Thread GHC 
#5515: panic! (the 'impossible' happened) with evil self-referential instance
-+--
Reporter:  andersk   |   Owner:
Type:  bug   |  Status:  new   
Priority:  normal|   Component:  Compiler  
 Version:  7.3   |Keywords:
Testcase:|   Blockedby:
  Os:  Unknown/Multiple  |Blocking:
Architecture:  Unknown/Multiple  | Failure:  Compile-time crash
-+--

Comment(by simonpj@…):

 commit 817d1b047b538e408a8758a18270c51d429de670
 {{{
 Author: Simon Peyton Jones simo...@microsoft.com
 Date:   Thu Sep 29 16:05:16 2011 +0100

 Fix scoping for RHS of associated type decls (fixes Trac #5515)

 We should not allow things like

 class C a b where
   type F a :: *

 instance C (p,q) r where
   type F (p,q) = r   -- No! fvs(rhs) should be a subset
  -- of fvs(lhs)

  compiler/hsSyn/HsDecls.lhs   |   11 ---
  compiler/rename/RnSource.lhs |   42
 ++
  2 files changed, 34 insertions(+), 19 deletions(-)
 }}}

-- 
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/5515#comment:1
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[GHC] #5515: panic! (the 'impossible' happened) with evil self-referential instance

2011-09-27 Thread GHC 
#5515: panic! (the 'impossible' happened) with evil self-referential instance
-+--
Reporter:  andersk   |   Owner:
Type:  bug   |  Status:  new   
Priority:  normal|   Component:  Compiler  
 Version:  7.3   |Keywords:
Testcase:|   Blockedby:
  Os:  Unknown/Multiple  |Blocking:
Architecture:  Unknown/Multiple  | Failure:  Compile-time crash
-+--
 This bit of code escaped from my fingertips:
 {{{
 #!hs
 {-# LANGUAGE ConstraintKinds, FlexibleInstances, TypeFamilies,
 UndecidableInstances #-}
 class ctx (Arg ctx) = Some ctx where type Arg ctx
 instance ctx a = Some ctx where type Arg ctx = a
 }}}
 and crashed GHC master with:
 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.3.20110927 for x86_64-unknown-linux):
 tcTyVarDetails a{tv aav} [tv]

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 This causes a similar crash without using ConstraintKinds:
 {{{
 #!hs
 {-# LANGUAGE FlexibleContexts, FlexibleInstances, MultiParamTypeClasses,
 TypeFamilies, UndecidableInstances #-}
 class C f a
 class C f (Arg f) = Some f where type Arg f
 instance C f a = Some f where type Arg f = a
 }}}

-- 
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/5515
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler

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