#2378: panic: lookupVers1, when standalone deriving Typeable and Data
-----------------------+----------------------------------------------------
Reporter: guest | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.8.2 | Severity: normal
Keywords: | Testcase:
Architecture: x86 | Os: MacOS X
-----------------------+----------------------------------------------------
When using !StandaloneDeriving and !DeriveDataTypeable on a rather large
AST, occasionally GHC 6.8.2 and GHC 6.8.3 RC bail with
{{{
[13 of 24] Compiling Language.C.AST.Generic
...
ghc-6.8.2.20080527: panic! (the 'impossible' happened)
(GHC version 6.8.2.20080527 for i386-apple-darwin):
lookupVers1 language-c-test-0.2:Language.C.AST.Constants
$cFlags{v}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
This is probably related to ticket #2011 (marked as milestone 6.8.3),
clean and rebuild resolves the problem temporarily.
I haven't been able to extract a small test case, but the problematic
source is available online at
http://code.haskell.org/language-c/src/Language/C/AST/Generic.hs
The bug is reproducible: (cabal) build, comment out the last 6 'deriving
Data' clauses (line 96-101), build again, uncomment, build again.
Side notes:
There is a warning (but no error !) when deriving a Typeable1 instance
(maybe related to #1825)
{{{
[13 of 24] Compiling Language.C.AST.Generic
Var/Type length mismatch:
[f{tv i1lc} [tv]]
[]
... [as above]
}}}
Finally, in GHC 6.9 standalone deriving Data was unsupported as of
01042008:
{{{
[13 of 24] Compiling Language.C.AST.Generic
Illegal binding of built-in syntax: $cCHeader
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2378>
GHC <http://www.haskell.org/ghc/>
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