Motivation for this change

This might be controversial. So I am open to different approaches.

This is the problem:

When installing packages via ghc.withPackages, ghcide will not work on projects relying on this. Because the cabal in that project will choose the version of a dependency provided by ghc.withPackageswhich thenghcidewhich does package discovery on it‘s own can‘t find, because it can‘t find packages from the wrappedghc`.

What I did

When building ghc.withPackages with ghcide as a package. The ghcide binary will be wrapped with the same environment variables as ghc.

Alternatives

The alternative is to tell users to grep the variables from the ghc wrapper used. But users will probably not find that documentation early and in between they have a broken ghcide which is hard to debug.

Problems

The problem with this approach is, that this will only help, if the user installs ghcide via ghc.withPackages. It wont work if ghcide is installed separately as haskellPackages.ghcide.

Yet I think that is useful setup that would be nice to support.

Of course special casing for certain packages in withPackages should be limited. If there is another more modular approach to achieve this, I would be open to that.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.