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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
  • Issues
  • #1988
Closed
Open
Issue created Dec 18, 2007 by guest@trac-guest

[6.8.1 regression] 6.8.2 panics in nameModule with -O2

The attached file makes GHC 6.8.2 panic:

$ ghc-6.8.2 -fforce-recomp -O2 -c PPrCF.hs 
ghc-6.8.2: panic! (the 'impossible' happened)
  (GHC version 6.8.2 for i386-apple-darwin):
        nameModule $wprCFTree{v sdg}

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

It only happens with -O2:

$ ghc-6.8.2 -fforce-recomp -O1 -c PPrCF.hs 

And only with 6.8.2:

$ ghc-6.8.1 -fforce-recomp -O2 -c PPrCF.hs
$ ghc-6.6.1 -fforce-recomp -O2 -c PPrCF.hs

-dcore-lint gives no additional information.

Adding a NOINLINE pragma for prCFTree makes the panic go away.

This problem and the NOINLINE work-around was found by Jean-Philippe Bernardy in GF.

Trac metadata
Trac field Value
Version 6.8.2
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
Test case
Differential revisions
BlockedBy
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Blocking
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Operating system
Architecture
Edited Mar 09, 2019 by Simon Marlow
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