#3966: Warn about useless UNPACK pragmas
---------------------------------+------------------------------------------
Reporter: tibbe | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: 6.12.1 | Keywords:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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I have on several occasions seen code with useless UNPACK pragmas.
Example:
{{{
data Foo a b = Foo {-# UNPACK #-} !(a -> b)
}}}
or
{{{
data Enum = A Int | B Double
data Foo = {-# UNPACK #-} !Enum
}}}
By emitting a warning for those cases where the pragma has no effect we
could help people understand how to use it correctly (rather than
sprinkling it everywhere and hope for the best).
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3966>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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