Bring back multiple output for binaries

[domenkozar]

@peti reverted #27209 since it broke haskell packages

The fix is quite simple:

diff --git a/pkgs/development/haskell-modules/with-packages-wrapper.nix b/pkgs/development/haskell-modules/with-packages-wrapper.nix
index ec7d961581a..725a2812f94 100644
--- a/pkgs/development/haskell-modules/with-packages-wrapper.nix
+++ b/pkgs/development/haskell-modules/with-packages-wrapper.nix
@@ -43,7 +43,7 @@ let
   libDir        = if isHaLVM then "$out/lib/HaLVM-${ghc.version}" else "$out/lib/${ghcCommand}-${ghc.version}";
   docDir        = "$out/share/doc/ghc/html";
   packageCfgDir = "${libDir}/package.conf.d";
-  paths         = lib.filter (x: x ? isHaskellLibrary) (lib.closePropagation packages);
+  paths         = map lib.getLib (lib.filter (x: x ? isHaskellLibrary) (lib.closePropagation packages));
   hasLibraries  = lib.any (x: x.isHaskellLibrary) paths;
   # CLang is needed on Darwin for -fllvm to work:
   # https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/code-generators.html

and a proof:

$ nix-shell -p "haskellPackages.ghcWithPackages (ps: [ps.mtl])" --run "ghc-pkg list mtl" -I ~/dev
these derivations will be built:
  /nix/store/ri4g0qry776qgirvw4wm4xb7yqsfbagv-ghc-8.0.2-with-packages.drv
building path(s) ‘/nix/store/s8ja7k00cd9ffd0h9prcaivmjgvdh8bd-ghc-8.0.2-with-packages’
/nix/store/s8ja7k00cd9ffd0h9prcaivmjgvdh8bd-ghc-8.0.2-with-packages/lib/ghc-8.0.2/package.conf.d
    mtl-2.2.1

cc @nc6

[Fuuzetsu]

It needs testing on hydra that it doesn't break anything else... I have wasted days fixing one thing and breaking another in this code ;/

[nc6]

I'll resurrect the PR, I did have a somewhat updated version

[nc6]

#32112 opened with your fix, needs hydra testing.

[vcunat]

Merged to master, but not all caveats seems solved yet.

[domenkozar]

@vcunat what's missing?

[vcunat]

@domenkozar: see the end of that PR's discussion: #32112

[domenkozar]

FYI: I have fixed ghcWithPackages and a few linux build failures.

What is left is:

• ghcWithPackages
• hevm
• ghcjsHEAD
• agda-prelude
• happy on darwin
• cabal2nix postInstall fixes
• tests

[domenkozar]

#32629

[domenkozar]

#58525 has landed and I've backported it to 18.09 and 19.03.

I think enabling this by default is big effort, but it's great that this feature is now available as a better way to justStaticExecutable. Maybe that should be now removed or do the bin splitting?

[chreekat]

@domenkozar would it be correct to say this issue can be closed, perhaps if you open a more specific issue about any remaining quibbles?

[stale]

Thank you for your contributions.

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