#4181: Template Haskell + -fdicts-strict fails
-------------------------------+--------------------------------------------
Reporter: LouisWasserman | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.12.3 | Keywords: template haskell strict
dictionary
Os: Linux | Testcase:
Architecture: x86_64 (amd64) | Failure: Compile-time crash
-------------------------------+--------------------------------------------
Comment(by LouisWasserman):
From the beginning, now:
{{{
module Foo where
import Language.Haskell.TH
foo :: Q ()
foo = return (TupE []) >>= const (return ())
}}}
ghc-core'ing Foo with -XTemplateHaskell -fdicts-strict yields
{{{
Foo.foo3 :: forall (m_aKr :: * -> *). Functor m_aKr
GblId
Foo.foo3 =
\ (@ m_aKr::* -> *) ->
Control.Exception.Base.runtimeError
@ Functor m_aKr
"Oops! Entered absent arg ww_sL6{v} [lid] <pred>base:Functor{tc 2a}
m{tv aKr} [tv]"
}}}
which certainly seems incorrect. To get GHC to actually crash,
{{{
module Bar where
import Foo
import Language.Haskell.TH
bar :: ()
bar = $(do x <- foo
x `seq` return (TupE []))
}}}
The following is verbatim from my command line:
{{{
lowas...@lowasser:~$ ghc --make Bar -fdicts-strict -XTemplateHaskell
-fforce-recomp
[1 of 2] Compiling Foo ( Foo.hs, Foo.o )
[2 of 2] Compiling Bar ( Bar.hs, Bar.o )
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Loading package pretty-1.0.1.1 ... linking ... done.
Loading package array-0.3.0.1 ... linking ... done.
Loading package containers-0.3.0.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
lowas...@lowasser:~$ ghc --make Bar -fdicts-strict -XTemplateHaskell
-fforce-recomp -O
[1 of 2] Compiling Foo ( Foo.hs, Foo.o )
[2 of 2] Compiling Bar ( Bar.hs, Bar.o )
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Loading package pretty-1.0.1.1 ... linking ... done.
Loading package array-0.3.0.1 ... linking ... done.
Loading package containers-0.3.0.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
Bar.hs:7:8:
Exception when trying to run compile-time code:
Oops! Entered absent arg ww_sL3{v} [lid]
<pred>base:GHC.Base.Functor{tc 2a} m{tv aKo} [tv]
Code: let
>>= = (>>=)
$dMonad = Language.Haskell.TH.Syntax.$fMonadQ
return = return
....
in
do { x <- foo;
seq x return (Language.Haskell.TH.Syntax.TupE
(GHC.Types.[])) }
In the expression:
$(do { x <- foo;
x `seq` return (TupE []) })
In the definition of `bar':
bar = $(do { x <- foo;
x `seq` return (TupE []) })
lowas...@lowasser:~$ ghci Bar -fdicts-strict -XTemplateHaskell -fforce-
recomp -O
GHCi, version 6.12.3: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
[1 of 2] Compiling Foo ( Foo.hs, interpreted )
[2 of 2] Compiling Bar ( Bar.hs, interpreted )
Loading package pretty-1.0.1.1 ... linking ... done.
Loading package array-0.3.0.1 ... linking ... done.
Loading package containers-0.3.0.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
Ok, modules loaded: Bar, Foo.
*Bar>
Leaving GHCi.
}}}
That is, it fails with ghc --make -O, but not with ghci -O or ghc --make
-O0.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4181#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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