INLINABLE pragma and newtypes prevents inlining

Compile the following code with 'ghc -O2 -ddump-simpl':

module A where

newtype Size = Size Int

{-# INLINABLE val2 #-}
val2 = Size 0

f n = case val2 of Size s -> s + s > n

With ghc-7.1.20110629, we get the following Core:

A.f1 =
  case A.val2 `cast` (A.NTCo:Size :: A.Size ~ GHC.Types.Int)
  of _ { GHC.Types.I# x_aoz ->
  GHC.Types.I# (GHC.Prim.+# x_aoz x_aoz)
  }

A.f = \ (n_ab1 :: GHC.Types.Int) -> GHC.Classes.gtInt A.f1 n_ab1

and we get something similar with ghc-7.0.3. In particular, for both versions of ghc, the addition s+s should be simplified to 0, but isn't.

Any of the following changes will let s+s simplify to 0:

• change newtype Size = ... into data Size = ...
• remove the INLINABLE pragma
• with ghc-7.0.3, turning the INLINABLE pragma into INLINE. However, with ghc-7.1.20110629, the INLINE pragma doesn't fix the problem.

Trac metadata

Trac field	Value
Version	7.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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