Add missing deps to devshell overlay, remove cabalWrapper (#1549)

since it needs custom shell setup and knowledge not wanted/necessary for
 many project. cabalWrapper can still be used from iohk-nix, until
 underlying issue is handled natively by cabal.

 Also remove packagesExes materialization attributes,
 not really useful anymore, given faster evaluation of recent haskell.nix

Author: jbgi

lib/project-overlays.nix

@@ -2,113 +2,35 @@
   lib
 , haskellLib
 }: {
+  # Provide a devshell profile (https://github.com/numtide/devshell),
+  # adapted from the project normal shell.
   devshell = final: prev: {
     devshell = let
-      cabal-install = final.pkgs.buildPackages.haskell-nix.cabal-install.${final.args.compiler-nix-name};
-      inherit (final.pkgs.buildPackages) runCommand runtimeShell;
-      cabalWrapper = runCommand "cabal" { inherit (cabal-install) meta; } ''
-        mkdir -p $out/bin
-        cat << EOF > $out/bin/cabal
-        #!${runtimeShell}
-        set -euo pipefail
-
-        find_up() {
-          while [[ \$PWD != / ]] ; do
-            if [[ -e "\$1" ]]; then
-              echo "\$PWD"
-              return
-            fi
-            cd ..
-          done
-        }
-
-        toplevel=\$(find_up "cabal.project")
-
-        if [[ -n "\$toplevel" ]]; then
-          cabal_project="\$toplevel/cabal.project"
-          nix_cabal_project=\$toplevel/.nix-cabal.project
-          extra_cabal_opts=("--project-file=\$nix_cabal_project")
-          awk '
-            # Add comment with explanation of file
-            BEGIN {
-              print "-- Generated from '"\$cabal_project"' by the wrapper script"
-              print "-- ${placeholder "out"}/cabal"
-              print "-- Add this file to your .gitignore\n"
-            }
-
-            # Matches all section starts
-            /^[^ ]/ {
-              # Remember the section name (they can span multiple lines)
-              section = \$0
-            }
-            # Matches every line
-            // {
-              # Only print the line if it is not in the section we want to omit
-              if (section != "source-repository-package")
-                print \$0
-            }
-          ' "\$cabal_project" > "\$nix_cabal_project"
-        else
-          extra_cabal_opts=()
-        fi
-
-        cabal=${placeholder "out"}/bin/.cabal
-        >&2 echo "\$cabal \''${extra_cabal_opts[@]} \$@"
-        exec "\$cabal" "\''${extra_cabal_opts[@]}" "\$@"
-        EOF
-        cp -rn ${cabal-install}/* $out/
-        cp ${cabal-install}/bin/cabal $out/bin/.cabal
-        chmod +x $out/bin/*
-      '';
     in {
-      packages = final.shell.nativeBuildInputs;
+      packages = final.shell.nativeBuildInputs
+      # devshell does not use pkgs.mkShell / pkgs.stdenv.mkDerivation,
+      # so we need to explicit required dependencies which
+      # are provided implicitely when using the normal shell:
+      ++ (with final.pkgs; [ binutils git gcc glibc gawk gnugrep bash coreutils pkg-config ]);
       env = lib.mapAttrsToList lib.nameValuePair {
         inherit (final.shell) CABAL_CONFIG NIX_GHC_LIBDIR;
       };
-      commands = [
-        {
-          package = cabalWrapper;
-          category = "development";
-        }
-      ];
     };
   };
 
-  projectComponents = final: prev: let
+  # Provides easily accessible attrset for each type of
+  # components belonging to the project packages.
+  projectComponents = final: prev: {
+    # local project packages:
     packages = haskellLib.selectProjectPackages final.hsPkgs;
-    # used to materialize `packages-exes.nix` (project packages and exes list) to avoid some evaluations:
-    packagesExes = lib.genAttrs
-      (lib.attrNames final.packages)
-      (name: lib.attrNames final.hsPkgs.${name}.components.exes);
-    collectExes = packagesExes: lib.listToAttrs (lib.concatLists (lib.mapAttrsToList
-      (p: map (exe: lib.nameValuePair exe final.hsPkgs.${p}.components.exes.${exe})) packagesExes));
-    in {
-      # local project packages:
-      packages = haskellLib.selectProjectPackages final.hsPkgs;
-      # set of all exes (as first level entries):
-      exes = collectExes packagesExes;
-      # set of all exes (as first level entries), mapped from a materialized set of packages and exes set (generated via `generatePackagesExes`):
-      exesFrom = packagesExesMat: collectExes (import packagesExesMat);
-      # `tests` are the test suites which have been built.
-      tests = haskellLib.collectComponents' "tests" final.packages;
-      # `benchmarks` (only built, not run).
-      benchmarks = haskellLib.collectComponents' "benchmarks" final.packages;
-      # `checks` collect results of executing the tests:
-      checks = haskellLib.collectChecks' final.packages;
-
-      generatePackagesExesMat = let
-        nixFile = builtins.toFile "packages-exes.nix" (lib.generators.toPretty {} packagesExes);
-      in final.pkgs.buildPackages.writeShellScript "generate-packages-exes" ''
-          set -euo pipefail
-
-          TARGET="$1"
-          TARGET_DIR="$(dirname "$TARGET")"
-
-          mkdir -p "$TARGET_DIR"
-          rm -rf "$TARGET"
-          cp -r ${nixFile} "$TARGET"
-          chmod -R +w "$TARGET"
-      '';
+    # set of all exes (as first level entries):
+    exes = lib.foldl' lib.mergeAttrs { } (map (p: p.components.exes) (lib.attrValues final.packages));
+    # `tests` are the test suites which have been built.
+    tests = haskellLib.collectComponents' "tests" final.packages;
+    # `benchmarks` (only built, not run).
+    benchmarks = haskellLib.collectComponents' "benchmarks" final.packages;
+    # `checks` collect results of executing the tests:
+    checks = haskellLib.collectChecks' final.packages;
   };
 
 }