#1194: tcrun032 regressed
-------------------------+--------------------------------------------------
Reporter: igloo | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.6.1
Component: Compiler | Version: 6.6
Severity: normal | Keywords:
Difficulty: Unknown | Testcase: tcrun032
Architecture: Unknown | Os: Unknown
-------------------------+--------------------------------------------------
The tcrun032 test:
{{{
{-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-}
-- This tests the recursive-dictionary stuff.
--
-- The derived instance needs
module Main where
data Fix f = In (f (Fix f)) deriving( Show, Eq )
data L x = Nil | Cons Int x deriving (Show, Eq)
main = do { print (In Nil);
print (In Nil == In Nil) }
}}}
now fails with:
{{{
tcrun032.hs:9:5:
No instance for (Show (f (Fix f)))
arising from the 'deriving' clause of a data type declaration
at tcrun032.hs:9:5
Possible fix: add an instance declaration for (Show (f (Fix f)))
When deriving the instance for `Show (Fix f)'
tcrun032.hs:9:5:
No instance for (Eq (f (Fix f)))
arising from the 'deriving' clause of a data type declaration
at tcrun032.hs:9:5
Possible fix: add an instance declaration for (Eq (f (Fix f)))
When deriving the instance for `Eq (Fix f)'
}}}
in the 6.6 branch. Both 6.6 and the HEAD work.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1194>
GHC <http://www.haskell.org/ghc/>
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