#7364: `foo !f = id . f` becomes non-strict with -O2
-----------------------------------------+----------------------------------
Reporter: shachaf | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.6.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Incorrect result at runtime | Testcase:
Blockedby: | Blocking:
Related: |
-----------------------------------------+----------------------------------
Comment(by ezyang):
Looks like a bug in the specializer.
{{{
ezyang@javelin:~/Dev/haskell$ ../ghc-build-master/inplace/bin/ghc-stage2
strict.hs -fforce-recomp -O -ddump-spec
[1 of 1] Compiling Main ( strict.hs, strict.o )
==================== Specialise ====================
Result size of Specialise = {terms: 19, types: 27, coercions: 10}
a_sn2
:: GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, () #)
[LclId,
Arity=1,
Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=1, Value=True,
ConLike=True, WorkFree=True, Expandable=True,
Guidance=IF_ARGS [0] 91 60}]
a_sn2 =
\ (eta_B1 :: GHC.Prim.State# GHC.Prim.RealWorld) ->
((System.IO.print
@ [GHC.Types.Char]
(GHC.Show.$fShow[] @ GHC.Types.Char GHC.Show.$fShowChar)
(GHC.Base.build
@ GHC.Types.Char
(\ (@ b_amP) -> GHC.CString.unpackFoldrCString# @ b_amP
"ok"#)))
`cast` (GHC.Types.NTCo:IO <()>
:: GHC.Types.IO ()
~#
(GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, () #))))
eta_B1
Main.main :: GHC.Types.IO ()
[LclIdX,
Arity=1,
Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=0, Value=True,
ConLike=True, WorkFree=True, Expandable=True,
Guidance=ALWAYS_IF(unsat_ok=True,boring_ok=True)}]
Main.main =
a_sn2
`cast` (Sym (GHC.Types.NTCo:IO <()>)
:: (GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, () #))
~#
GHC.Types.IO ())
a_sn4
:: GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, () #)
[LclId,
Arity=1,
Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=1, Value=True,
ConLike=True, WorkFree=True, Expandable=True,
Guidance=IF_ARGS [0] 21 60}]
a_sn4 =
\ (eta_Xb :: GHC.Prim.State# GHC.Prim.RealWorld) ->
((GHC.TopHandler.runMainIO @ () Main.main)
`cast` (GHC.Types.NTCo:IO <()>
:: GHC.Types.IO ()
~#
(GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, () #))))
eta_Xb
:Main.main :: GHC.Types.IO ()
[LclIdX,
Arity=1,
Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=0, Value=True,
ConLike=True, WorkFree=True, Expandable=True,
Guidance=ALWAYS_IF(unsat_ok=True,boring_ok=True)}]
:Main.main =
a_sn4
`cast` (Sym (GHC.Types.NTCo:IO <()>)
:: (GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, () #))
~#
GHC.Types.IO ())
Linking strict ...
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7364#comment:1>
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