gnu: ghc-9.2: Make Cabal respect GHC_PACKAGE_PATH

**tl;dr** Applying this patch makes Cabal work in Guix environments
and ensures that Cabal picks up Haskell packages installed via Guix.

Guix makes heavy use of GHC_PACKAGE_PATH to make GHC pickup Haskell
packages installed via the Guix package manager. The environment
variable is set using native-search-paths from the GHC packages.

Unfortunately, upstream Cabal does presently not respect
GHC_PACKAGE_PATH. If this environment variable is set, `cabal build`
and other commands will terminate. For building packages, Guix does
not make much use of cabal-install hence this is not as big of an
issue. However, cabal-install does therefore presently not work
out-of-the-box in environments created by Guix. For example,
in `guix shell` environments. This makes it essentially impossible
to use Guix for setting up development environments for Haskell software.

Cabal upstream is aware of this issue and a patch exists to workaround
this problem. The patch is currently not merged upstream due to issues
related to reconfiguration (changing GHC_PACKAGE_PATH between `cabal
configure` and `cabal build`). However, I would argue that this edge
case is not that relevant for Guix and therefore propose including
this patch with the Cabal Guix package. As outlined above, cabal-install
is not usable by default presently, and I would therefore argue that
this is a major improvement over the current situation. I am willing to
work with Cabal upstream to have this issue fixed upstream eventually.

Note that this requires patching the GHC package instead of the
cabal-install package as Guix uses the version of the Cabal package
<https://hackage.haskell.org/package/Cabal> distributed with GHC.

See: https://github.com/haskell/cabal/issues/3728

* gnu/packages/haskell-apps.scm (cabal-install): Include patch
to support the GHC_PACKAGE_PATH environment variable.

Signed-off-by: Sören Tempel <soeren@soeren-tempel.net>
Signed-off-by: Lars-Dominik Braun <lars@6xq.net>
Change-Id: Ib77ffa937b878690d0e2d8964b534842b99da039
This commit is contained in:
Sören Tempel 2023-12-19 11:05:32 +01:00 committed by Lars-Dominik Braun
parent 208c2d63bb
commit 9236047476
No known key found for this signature in database
GPG key ID: F663943E08D8092A
3 changed files with 70 additions and 1 deletions

View file

@ -1330,6 +1330,7 @@ dist_patch_DATA = \
%D%/packages/patches/geoclue-config.patch \
%D%/packages/patches/gettext-libunicode-update.patch \
%D%/packages/patches/ghc-8.0-fall-back-to-madv_dontneed.patch \
%D%/packages/patches/ghc-9.2-cabal-support-package-path.patch \
%D%/packages/patches/ghc-9.2-glibc-2.33-link-order.patch \
%D%/packages/patches/ghc-9.2-grep-warnings.patch \
%D%/packages/patches/ghc-testsuite-dlopen-pie.patch \

View file

@ -1444,7 +1444,8 @@ (define-public ghc-9.2
(sha256
(base32
"07028i0hm74svvq9b3jpkczaj6lsdgn3hgr4wa7diqiq3dypj1h6"))
(patches (search-patches "ghc-9.2-glibc-2.33-link-order.patch"))))
(patches (search-patches "ghc-9.2-glibc-2.33-link-order.patch"
"ghc-9.2-cabal-support-package-path.patch"))))
(arguments
(substitute-keyword-arguments (package-arguments base)
((#:phases phases '%standard-phases)

View file

@ -0,0 +1,67 @@
Without this patch, Cabal terminates if GHC_PACKAGE_PATH is set. This is
an annoyance with Guix as it makes heavy use of GHC_PACKAGE_PATH to have
GHC pickup Haskell package installed via Guix. Therefore, Cabal does
presently not work by default in environments created by Guix. This is
a workaround which makes Cabal respect GHC_PACKAGE_PATH.
Taken from https://github.com/haskell/cabal/issues/3728
diff -upr a/libraries/Cabal/Cabal/src/Distribution/Simple/GHC.hs b/libraries/Cabal/Cabal/src/Distribution/Simple/GHC.hs
--- a/libraries/Cabal/Cabal/src/Distribution/Simple/GHC.hs 2022-11-06 20:41:17.000000000 +0100
+++ b/libraries/Cabal/Cabal/src/Distribution/Simple/GHC.hs 2023-12-18 14:34:15.148911717 +0100
@@ -71,6 +71,7 @@ module Distribution.Simple.GHC (
) where
import Prelude ()
+import Distribution.Compat.Environment (lookupEnv)
import Distribution.Compat.Prelude
import qualified Distribution.Simple.GHC.Internal as Internal
@@ -117,7 +118,7 @@ import System.Directory
, canonicalizePath, removeFile, renameFile, getDirectoryContents )
import System.FilePath ( (</>), (<.>), takeExtension
, takeDirectory, replaceExtension
- ,isRelative )
+ , isRelative, searchPathSeparator )
import qualified System.Info
#ifndef mingw32_HOST_OS
import System.Posix (createSymbolicLink)
@@ -333,9 +334,11 @@ getInstalledPackages :: Verbosity -> Com
-> ProgramDb
-> IO InstalledPackageIndex
getInstalledPackages verbosity comp packagedbs progdb = do
- checkPackageDbEnvVar verbosity
checkPackageDbStack verbosity comp packagedbs
- pkgss <- getInstalledPackages' verbosity packagedbs progdb
+ envPackageDBs <-
+ maybe [] (map SpecificPackageDB . unintersperse searchPathSeparator)
+ <$> lookupEnv "GHC_PACKAGE_PATH"
+ pkgss <- getInstalledPackages' verbosity (envPackageDBs ++ packagedbs) progdb
index <- toPackageIndex verbosity pkgss progdb
return $! hackRtsPackage index
@@ -405,10 +408,6 @@ getUserPackageDB _verbosity ghcProg plat
packageConfFileName = "package.conf.d"
ghcVersion = fromMaybe (error "GHC.getUserPackageDB: no ghc version") $ programVersion ghcProg
-checkPackageDbEnvVar :: Verbosity -> IO ()
-checkPackageDbEnvVar verbosity =
- Internal.checkPackageDbEnvVar verbosity "GHC" "GHC_PACKAGE_PATH"
-
checkPackageDbStack :: Verbosity -> Compiler -> PackageDBStack -> IO ()
checkPackageDbStack verbosity comp =
if flagPackageConf implInfo
@@ -461,8 +460,11 @@ getInstalledPackagesMonitorFiles :: Verb
-> ProgramDb
-> [PackageDB]
-> IO [FilePath]
-getInstalledPackagesMonitorFiles verbosity platform progdb =
- traverse getPackageDBPath
+getInstalledPackagesMonitorFiles verbosity platform progdb packageDBs = do
+ envPackageDBs <-
+ maybe [] (map SpecificPackageDB . unintersperse searchPathSeparator)
+ <$> lookupEnv "GHC_PACKAGE_PATH"
+ traverse getPackageDBPath (envPackageDBs ++ packageDBs)
where
getPackageDBPath :: PackageDB -> IO FilePath
getPackageDBPath GlobalPackageDB =