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 <-# Chinese (simplified) translation of the Guix manual.
# Copyright (C) 2013-2019 the authors of Guix (msgids) and the following authors (msgstr)
# This file is distributed under the same license as the guix manual package.
# Meiyo Peng &lt;meiyo@riseup.net&gt;, 2019.
# 郑俊杰 &lt;873216071@qq.com&gt;, 2021, 2023, 2024.
# Liu Tao &lt;lyuutau@outlook.com&gt;, 2021, 2023.
# Xinglu Chen &lt;public@yoctocell.xyz&gt;, 2021.
# Charles Lee &lt;lchopn@gmail.com&gt;, 2021.
# Went He &lt;1437061699@qq.com&gt;, 2021, 2023.
# Whired Planck &lt;fungdaat31@outlook.com&gt;, 2022.
# chin housin &lt;sharingfun@163.com&gt;, 2022.
# Julien Lepiller &lt;fedora-account@lepiller.eu&gt;, 2022.
# Yang Yulin &lt;yylteam@icloud.com&gt;, 2022.
# Thomas Cheng &lt;orangecza@gmail.com&gt;, 2023.
# Hilton Chain &lt;yareli@ultrarare.space&gt;, 2023.
# Yi Cao &lt;cygauss@outlook.com&gt;, 2023.
# Burgess Chang &lt;bsc@brsvh.org&gt;, 2023.
# Florian Pelz &lt;pelzflorian@pelzflorian.de&gt;, 2023, 2024.
# a x &lt;meruarasu@email1.io&gt;, 2023.
# Integral &lt;integral@member.fsf.org&gt;, 2024.
# Celestial y &lt;clsty@celestialy.top&gt;, 2024.
# Weblate Translation Memory &lt;noreply-mt-weblate-translation-memory@weblate.org&gt;, 2024.
# voyage 200 &lt;hello_cmd@outlook.com&gt;, 2024.
msgid &quot;&quot;
msgstr &quot;&quot;
&quot;Project-Id-Version: gu