Nixify hlint (#1293)

I accidentally introduced an hlint failure in #1292, which got merged as
the job is not marked as required. This PR resolves this by adding it to
the Hydra jobset.

Author: amesgen

.github/workflows/hlint.yml

@@ -39,7 +39,7 @@ let
     native = {
       haskell96 = mkHaskellJobsFor pkgs.hsPkgs;
     } // lib.optionalAttrs (buildSystem == "x86_64-linux") {
-      formatting = import ./formatting.nix pkgs;
+      formattingLinting = import ./formatting-linting.nix pkgs;
       inherit (pkgs) consensus-pdfs agda-spec;
 
       # ensure we can still build on 8.10, can be removed soon

nix/ci.nix

@@ -24,17 +24,29 @@ let
       echo $EXIT_CODE > $out
     fi
   '';
-  formatting = {
+  formattingLinting = {
     stylish = checkFormatting pkgs.stylish-haskell ../scripts/ci/run-stylish.sh;
     cabal-gild = checkFormatting pkgs.cabal-gild ../scripts/ci/run-cabal-gild.sh;
     nixpkgs-fmt = checkFormatting pkgs.nixpkgs-fmt ../scripts/ci/run-nixpkgs-fmt.sh;
     dos2unix = checkFormatting pkgs.dos2unix ../scripts/ci/run-dos2unix.sh;
+    hlint = pkgs.runCommand "hlint"
+      {
+        buildInputs = [ pkgs.hlint ];
+        src = ../.;
+      } ''
+      unpackPhase
+      cd $sourceRoot
+
+      hlint -j .
+
+      touch $out
+    '';
   };
 in
-formatting // {
+formattingLinting // {
   all = pkgs.releaseTools.aggregate {
     name = "consensus-formatting";
-    meta.description = "Run all formatters";
-    constituents = lib.collect lib.isDerivation formatting;
+    meta.description = "Run all formatters and linters";
+    constituents = lib.collect lib.isDerivation formattingLinting;
   };
 }

nix/formatting.nix nix/formatting-linting.nixnix/formatting.nix renamed to nix/formatting-linting.nix

@@ -12,6 +12,7 @@ hsPkgs.shellFor {
     pkgs.stylish-haskell
     pkgs.dos2unix
     pkgs.cabal-gild
+    pkgs.hlint
     pkgs.cabal-hoogle
     pkgs.ghcid
 

nix/shell.nix

@@ -35,6 +35,8 @@ in
 
   cabal-gild = tool "cabal-gild" "1.5.0.1" { };
 
+  hlint = tool "hlint" "3.8" { };
+
   haskellBuildUtils = prev.haskellBuildUtils.override {
     inherit (final.hsPkgs.args) compiler-nix-name;
     index-state = tool-index-state;

nix/tools.nix

@@ -5,7 +5,6 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
-{-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-}