Allow using GHC with ld.lld

[TeofilC]

We need to add llvmPackages.bintools to the nativeBuildInputs of builders when using this and we need to configure GHC to use ld.lld.

Resolves #2317

[purefn]

This is great, thanks! What's the best way to enable it for use with pkgs.haskell-nix.project'? Right now it looks like it would require using an overlay to override the useLdLld setting in pkgs.haskell-nix.compiler.ghcXXX. Is there an easier way that would apply it to all versions of ghc - we build with ghc96, ghc910, and ghc912, so having an easy way of setting it for all of them would be great.

[TeofilC]

@purefn The way I have been doing this is by just adding a commit to our fork that always enables it like so: circuithub@bf4b789

There is probably a better way to do it, but this is the easiest thing to do so that's what I've been doing 😅

I'll leave the job of adding a nicer interface to access this to someone else.

[purefn]

I think I found an easier way to do that.

  project = haskell-nix.project' ({config, ...}: {

    compilerSelection = p: builtins.mapAttrs (_: x: x.override { hadrianEvalPackages = config.evalPackages; useLdLld = true; }) p.haskell-nix.compiler;

But it doesn't seem to work on macOS.

ghc> checking for arm64-apple-darwin-ld... /nix/store/3py6dyxg2h95vlba8dil3anhighi0dqj-llvm-binutils-wrapper-15.0.7/bin/ld.lld
ghc> checking for arm64-apple-darwin-nm... /nix/store/idmz24ps83r9mz2hkxdqwv6y4v2v7x28-cctools-binutils-darwin-1010.6/bin/nm
ghc> checking whether nm program is broken... no
ghc> configure: Setting cmd
ghc> checking for ld.gold object merging bug (binutils 22266)... ld.lld: error: unknown argument '-platform_version'
ghc> ld.lld: error: unknown argument '-no_dtrace_dof'
ghc> configure: Checking whether /nix/store/3py6dyxg2h95vlba8dil3anhighi0dqj-llvm-binutils-wrapper-15.0.7/bin/ld.lld can merge objects
ghc> ld.lld: error: unknown argument '-platform_version'
ghc> ld.lld: error: unknown argument '-no_dtrace_dof'
ghc> ld.lld: error: cannot open macos: No such file or directory
ghc> ld.lld: error: cannot open 11.3: No such file or directory
ghc> ld.lld: error: cannot open 11.3: No such file or directory
ghc> ld.lld: error: conftesta.o: unknown file type
ghc> ld.lld: error: conftestb.o: unknown file type
ghc> configure: error:  /nix/store/3py6dyxg2h95vlba8dil3anhighi0dqj-llvm-binutils-wrapper-15.0.7/bin/ld.lld could not merge objects

Is this something that will only work on Linux? Sorry, not up to date on my linkers.

[TeofilC]

Nice!

Sorry I have no idea about linkers on MacOS