#1482: unsafeCoerce# doesn't always fully coerce
--------------------------------------+-------------------------------------
Reporter: [EMAIL PROTECTED] | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.6.1
Severity: normal | Keywords: unsafeCoerce#
Difficulty: Unknown | Os: Linux
Testcase: | Architecture: x86
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{{{
{-# OPTIONS_GHC -fglasgow-exts #-}
import GHC.Prim( unsafeCoerce# )
e1 = unsafeCoerce# (+)
e2 = unsafeCoerce# shows
}}}
{{{e1}}} coerces fine, even with the {{{Num}}} constraint, but {{{e2}}}
does not. The error for e2 is
{{{
Ambiguous type variable `a' in the constraint:
`Show a' arising from use of `shows' at T.lhs:7:20-24
Probable fix: add a type signature that fixes these type variable(s)
}}}
Weirder still, ghci coerces {{{shows}}} fine:
{{{
*Main> :t unsafeCoerce# shows
unsafeCoerce# shows :: forall b. b
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1482>
GHC <http://www.haskell.org/ghc/>
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