state hack causes unneeded value to be evaluated

The following code prints "Main: Why?" when compiled with ghc -O1. With -fno-state-hack it works fine.

data X = X ()

{-# NOINLINE newX #-}
newX :: () -> IO X
newX n = do
    let {-# NOINLINE value #-}
        value = n
    return (X value)

main = do
    x <- newX (error "Why?")
    case x of
        X _ -> return ()

Both pragmas are needed to exhibit the bug.

(In my actual code, value is an unsafePerformIO -- this was the motivation for adding the pragmas.)

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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