#2182: ghc sessions (--make, --interactive, ghc api) erroneously retain
instances
---------------------+------------------------------------------------------
Reporter: claus | Owner:
Type: bug | Status: new
Priority: low | Milestone: _|_
Component: GHCi | Version: 6.9
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: Unknown
Os: Unknown |
---------------------+------------------------------------------------------
Changes (by claus):
* summary: ghci session retains instances after :m -Module => ghc
sessions (--make, --interactive, ghc api)
erroneously retain instances
Comment:
(changed ticket title to reflect broader scope)
This bug affects all ghc sessions, not just ghci. In particular:
- Cabal uses `ghc --make`, which can fail because of this bug
- Haddock 2 uses the ghc api, which can fail because of this bug
In both cases, the workaround is to repeat the command, so that it
continues with a fresh ghc session, but that will not at all be obvious to
users.
Example:
{{{
$ darcs get http://www.cs.kent.ac.uk/~cr3/toolbox/haskell/syb-utils
Finished getting.
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.8.3
$ cd syb-utils/
$ runhaskell.exe Setup.hs configure
Configuring syb-utils-0.0.2008.8.19...
Warning: No license-file field.
$ runhaskell.exe Setup.hs build
Preprocessing library syb-utils-0.0.2008.8.19...
Building syb-utils-0.0.2008.8.19...
[1 of 6] Compiling Data.Generics.Instances.Dubious (
Data/Generics/Instances/Dubious.hs, dist\build/
Data/Generics/Instances/Dubious.o )
[2 of 6] Compiling Data.Generics.Utils ( Data/Generics/Utils.hs,
dist\build/Data/Generics/Utils.o )
[3 of 6] Compiling Data.Generics.NoInstances (
Data/Generics/NoInstances.hs, dist\build/Data/Generic
s/NoInstances.o )
[4 of 6] Compiling Data.Generics.GPS ( Data/Generics/GPS.hs,
dist\build/Data/Generics/GPS.o )
[5 of 6] Compiling Data.Generics.Instances.Standard (
Data/Generics/Instances/Standard.hs, dist\buil
d/Data/Generics/Instances/Standard.o )
Data/Generics/Instances/Standard.hs:61:0:
Duplicate instance declarations:
instance Data Bool
-- Defined at Data/Generics/Instances/Standard.hs:(61,0)-(68,28)
instance Data Bool -- Defined in Data.Generics.Instances
..
$ runhaskell.exe Setup.hs build
Preprocessing library syb-utils-0.0.2008.8.19...
Building syb-utils-0.0.2008.8.19...
[5 of 6] Compiling Data.Generics.Instances.Standard (
Data/Generics/Instances/Standard.hs, dist\buil
d/Data/Generics/Instances/Standard.o )
[6 of 6] Compiling Data.Generics.Alt ( Data/Generics/Alt.hs,
dist\build/Data/Generics/Alt.o )
c:\ghc\ghc-6.8.3\bin\ar.exe: creating dist\build\libHSsyb-
utils-0.0.2008.8.19.a
}}}
Confusingly, the behaviour is compiler-version and tool dependent:
{{{
$ runhaskell.exe Setup.hs clean
cleaning...
$ /cygdrive/c//fptools/ghc/ghc/stage2-inplace/ghc.exe --version
The Glorious Glasgow Haskell Compilation System, version 6.9.20080816
$ runhaskell Setup configure --with-
compiler=c:/fptools/ghc/ghc/stage2-inplace/ghc.exe --with-hc-pk
g=c:/fptools/ghc/utils/ghc-pkg/install-inplace/bin/ghc-pkg.exe --with-
haddock=c:/Program\ Files/Has
kell/bin/haddock.exe -fGhcApi
Configuring syb-utils-0.0.2008.8.19...
Warning: No license-file field.
[EMAIL PROTECTED] ~/tst/ghc-session-bug/syb-utils
$ runhaskell.exe Setup.hs build
Preprocessing library syb-utils-0.0.2008.8.19...
Building syb-utils-0.0.2008.8.19...
[1 of 9] Compiling Data.Generics.Instances.Dubious (
Data\Generics\Instances\Dubious.hs, dist\build\
Data\Generics\Instances\Dubious.o )
[2 of 9] Compiling Data.Generics.Instances.Standard (
Data\Generics\Instances\Standard.hs, dist\buil
d\Data\Generics\Instances\Standard.o )
[3 of 9] Compiling Data.Generics.Utils ( Data\Generics\Utils.hs,
dist\build\Data\Generics\Utils.o )
[4 of 9] Compiling Data.Generics.NoInstances (
Data\Generics\NoInstances.hs, dist\build\Data\Generic
s\NoInstances.o )
[5 of 9] Compiling Data.Generics.GPS ( Data\Generics\GPS.hs,
dist\build\Data\Generics\GPS.o )
[6 of 9] Compiling Data.Generics.Alt ( Data\Generics\Alt.hs,
dist\build\Data\Generics\Alt.o )
[7 of 9] Compiling GHC.Syb.Instances0 ( GHC\Syb\Instances0.hs,
dist\build\GHC\Syb\Instances0.o )
[8 of 9] Compiling GHC.Syb.Instances ( GHC\Syb\Instances.hs,
dist\build\GHC\Syb\Instances.o )
[9 of 9] Compiling GHC.Syb.Utils ( GHC\Syb\Utils.hs,
dist\build\GHC\Syb\Utils.o )
c:\ghc\ghc-6.8.3\bin\ar.exe: creating dist\build\libHSsyb-
utils-0.0.2008.8.19.a
}}}
Note that ghc head and ghc 6.8.3 process the dependencies in a different
order, which probably explains why the bug isn't triggered in head:
`Data.Generics.Instances.Dubious` and `Data.Generics.Instances.Standard`
represent two halves of `base`'s `Data.Generics.Instances`; the latter
isn't explicitly imported here, but `Data.Generics.GPS` uses
`Data.IntMap`, which inadvertedly re-exports the instances from
`Data.Generics.Instances`.
If `Data.Generics.Instances.*` are compiled first, ghc doesn't complain
about alternative instances being present, but if either of
`Data.Generics.Instances.*` is compiled after `Data.Generics.GPS`, the
erroneously retained instances conflict with the newly defined ones.
We can confirm the bug is still there by trying to haddock2 the package
with a fresh darcs haddock, freshly compiled with the same ghc head:
{{{
$ runhaskell.exe Setup.hs clean
cleaning...
$ /cygdrive/c/Program\ Files/Haskell/bin/haddock.exe --version
Haddock version 2.2.2, (c) Simon Marlow 2006
Ported to use the GHC API by David Waern 2006-2008
$ /cygdrive/c/Program\ Files/Haskell/bin/haddock.exe +RTS --info
[("GHC RTS", "Yes")
,("GHC version", "6.9.20080816")
,("RTS way", "rts")
,("Host platform", "i386-unknown-mingw32")
,("Build platform", "i386-unknown-mingw32")
,("Target platform", "i386-unknown-mingw32")
,("Compiler unregisterised", "NO")
,("Tables next to code", "YES")
]
$ runhaskell Setup configure --with-
compiler=c:/fptools/ghc/ghc/stage2-inplace/ghc.exe --with-hc-pk
g=c:/fptools/ghc/utils/ghc-pkg/install-inplace/bin/ghc-pkg.exe --with-
haddock=c:/Program\ Files/Haskell/bin/haddock.exe -fGhcApi
Configuring syb-utils-0.0.2008.8.19...
Warning: No license-file field.
[EMAIL PROTECTED] ~/tst/ghc-session-bug/syb-utils
$ runhaskell.exe Setup.hs haddock
Preprocessing library syb-utils-0.0.2008.8.19...
Running Haddock for syb-utils-0.0.2008.8.19...
Preprocessing library syb-utils-0.0.2008.8.19...
Warning: Cannot read c:\fptools\ghc\compiler\dist-
stage2\doc\html\ghc\ghc.haddock:
"Magic number mismatch: couldn't load interface file:
c:\\fptools\\ghc\\compiler\\dist-stage2\\doc\\html\\ghc\\ghc.haddock"
Skipping this interface.
Warning: Cannot read
c:\fptools\ghc\libraries\base\dist\doc\html\base\base.haddock:
"Magic number mismatch: couldn't load interface file:
c:\\fptools\\ghc\\libraries\\base\\dist\\doc\\html\\base\\base.haddock"
Skipping this interface.
Warning: Cannot read
c:\fptools\ghc\libraries\containers\dist\doc\html\containers\containers.haddock
:
"Magic number mismatch: couldn't load interface file:
c:\\fptools\\ghc\\libraries\\containers\\dist\\doc\\html\\containers\\containers.haddock"
Skipping this interface.
Data\Generics\Instances\Dubious.hs:59:9:
Duplicate instance declarations:
instance (Data a, Integral a) => Data (Ratio a)
-- Defined at Data\Generics\Instances\Dubious.hs:59:9-46
instance (Data a, Integral a) => Data (Ratio a)
-- Defined in Data.Generics.Instances
..
$ runhaskell.exe Setup.hs haddock
Preprocessing library syb-utils-0.0.2008.8.19...
Running Haddock for syb-utils-0.0.2008.8.19...
Preprocessing library syb-utils-0.0.2008.8.19...
Warning: Cannot read c:\fptools\ghc\compiler\dist-
stage2\doc\html\ghc\ghc.haddock:
"Magic number mismatch: couldn't load interface file:
c:\\fptools\\ghc\\compiler\\dist-stage2\\doc\\html\\ghc\\ghc.haddock"
Skipping this interface.
Warning: Cannot read
c:\fptools\ghc\libraries\base\dist\doc\html\base\base.haddock:
"Magic number mismatch: couldn't load interface file:
c:\\fptools\\ghc\\libraries\\base\\dist\\doc\\html\\base\\base.haddock"
Skipping this interface.
Warning: Cannot read
c:\fptools\ghc\libraries\containers\dist\doc\html\containers\containers.haddock
:
"Magic number mismatch: couldn't load interface file:
c:\\fptools\\ghc\\libraries\\containers\\dist\\doc\\html\\containers\\containers.haddock"
Skipping this interface.
Warning: in export list of "Data.Generics.NoInstances": module not found:
"Data.Generics.Basics"
Warning: in export list of "Data.Generics.NoInstances": module not found:
"Data.Generics.Aliases"
Warning: in export list of "Data.Generics.NoInstances": module not found:
"Data.Generics.Schemes"
Warning: in export list of "Data.Generics.NoInstances": module not found:
"Data.Generics.Text"
Warning: in export list of "Data.Generics.NoInstances": module not found:
"Data.Generics.Twins"
Warning: in export list of "Data.Generics.Alt": module not found:
"Data.Generics.Basics"
Warning: in export list of "Data.Generics.Alt": module not found:
"Data.Generics.Aliases"
Warning: in export list of "Data.Generics.Alt": module not found:
"Data.Generics.Schemes"
Warning: in export list of "Data.Generics.Alt": module not found:
"Data.Generics.Text"
Warning: in export list of "Data.Generics.Alt": module not found:
"Data.Generics.Twins"
Warning: syb-utils-0.0.2008.8.19:GHC.Syb.Instances: could not find link
destinations for:
Data.Typeable.TyCon
Warning: syb-utils-0.0.2008.8.19:GHC.Syb.Instances0: could not find link
destinations for:
Data.Typeable.TyCon
Warning: syb-utils-0.0.2008.8.19:GHC.Syb.Utils: could not find link
destinations for:
GHC.Classes.Eq GHC.Classes.Ord GHC.Show.Show Data.Generics.Basics.Data
GHC.Types.Int GHC.Base.St
ring Data.Generics.Aliases.GenericQ GHC.Bool.Bool
Warning: syb-utils-0.0.2008.8.19:Data.Generics.GPS: could not find link
destinations for:
Data.Generics.Basics.Data Data.Generics.Aliases.GenericQ
Data.Typeable.Typeable Data.Typeable.Typeable1 Data.Maybe.Maybe
Data.IntMap.IntMap Data.IntSet.IntSet GHC.Types.Int
Data.Generics.Aliases.GenericT
Warning: syb-utils-0.0.2008.8.19:Data.Generics.Utils: could not find link
destinations for:
Control.Applicative.Applicative Data.Typeable.Typeable1
Data.Typeable.Typeable Data.Generics.Basics.Data Data.Generics.Utils.X
Warning: syb-utils-0.0.2008.8.19:Data.Generics.Instances.Standard: could
not find link destinations
for:
Data.Typeable.TyCon
Documentation created: dist\doc\html\syb-utils\index.html
}}}
What are the chances of getting this fixed?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2182#comment:4>
GHC <http://www.haskell.org/ghc/>
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