haskell: Propagate cabal dependencies to user env

Before this commit, if a haskell library X depends on Y, and X was added to
systemPackages, only X would be available in the user environment. Y
would not be avialable, which causes X to be broken. This commit solves
the issue by setting propagatedUserEnvPkgs to all packages X depends
on when X is a library.

1 files changed, 5 insertions, 0 deletions

diff --git a/pkgs/build-support/cabal/default.nix b/pkgs/build-support/cabal/default.nix
index 14bd01c7346e..b17f720e5618 100644
--- a/pkgs/build-support/cabal/default.nix
+++ b/pkgs/build-support/cabal/default.nix
@@ -46,6 +46,7 @@ assert !enableStaticLibraries -> versionOlder "7.7" ghc.version;
           x : (removeAttrs x internalAttrs) // {
                 buildInputs           = filter (y : ! (y == null)) x.buildInputs;
                 propagatedBuildInputs = filter (y : ! (y == null)) x.propagatedBuildInputs;
+                propagatedUserEnvPkgs = filter (y : ! (y == null)) x.propagatedUserEnvPkgs;
                 doCheck               = enableCheckPhase && x.doCheck;
               };
 
@@ -96,6 +97,10 @@ assert !enableStaticLibraries -> versionOlder "7.7" ghc.version;
             # have to check for its existence
             propagatedBuildInputs = if self.isLibrary then self.buildDepends ++ self.extraLibraries ++ self.pkgconfigDepends else [];
 
+            # By default, also propagate all dependencies to the user environment. This is required, otherwise packages would be broken, because
+            # GHC also needs all dependencies to be available.
+            propagatedUserEnvPkgs = if self.isLibrary then self.buildDepends else [];
+
             # library directories that have to be added to the Cabal files
             extraLibDirs = [];