use latest nix-cargo-integration which depends on dream2nix (helix-ed…

…itor#1758)

https://github.com/nix-community/dream2nix is a fairly new and
cool-looking project for adapting upstream package manager outputs
(lockfiles mostly it would seem) for nix.

This should improve the ability to cross-compile. As a more concrete
measure of improvement, `nix flake check' now succeeds 🎉

flake.nix

@@ -12,68 +12,45 @@
       inputs.nixpkgs.follows = "nixpkgs";
       inputs.rustOverlay.follows = "rust-overlay";
     };
+    # NOTE: the flake looks like it is hanging when it pulls this input because
+    # the submodules take a long time to clone. This will be fixed in #1659.
+    helix = {
+      url = "https://github.com/helix-editor/helix.git";
+      type = "git";
+      submodules = true;
+      flake = false;
+    };
   };
 
-  outputs = inputs@{ self, nixCargoIntegration, ... }:
+  outputs = inputs@{ nixCargoIntegration, helix, ... }:
     nixCargoIntegration.lib.makeOutputs {
       root = ./.;
-      buildPlatform = "crate2nix";
       renameOutputs = { "helix-term" = "helix"; };
       # Set default app to hx (binary is from helix-term release build)
       # Set default package to helix-term release build
-      defaultOutputs = { app = "hx"; package = "helix"; };
+      defaultOutputs = {
+        app = "hx";
+        package = "helix";
+      };
       overrides = {
         crateOverrides = common: _: rec {
-          # link languages and theme toml files since helix-core/helix-view expects them
-          helix-core = _: { preConfigure = "ln -s ${common.root}/{languages.toml,theme.toml,base16_theme.toml} .."; };
-          helix-view = _: { preConfigure = "ln -s ${common.root}/{languages.toml,theme.toml,base16_theme.toml} .."; };
-          helix-syntax = prev: {
-            src =
-              let
-                pkgs = common.pkgs;
-                helix = pkgs.fetchgit {
-                  url = "https://github.com/helix-editor/helix.git";
-                  rev = "d62ad8b595a4f901b9c5dba1bb6e8f70ece395bf";
-                  fetchSubmodules = true;
-                  sha256 = "sha256-X0N2clg2DQQ2bwyBrZVeaXLoSKaQ7NALydnd2eJzECg=";
-                };
-              in
-              pkgs.runCommand prev.src.name { } ''
-                mkdir -p $out
-                ln -s ${prev.src}/* $out
-                ln -sf ${helix}/helix-syntax/languages $out
-              '';
-            preConfigure = "mkdir -p ../runtime/grammars";
-            postInstall = "cp -r ../runtime $out/runtime";
+          helix-term = prev: {
+            buildInputs = (prev.buildInputs or [ ]) ++ [ common.cCompiler.cc.lib ];
+            nativeBuildInputs = (prev.nativeBuildInputs or [ ]) ++ [ common.pkgs.makeWrapper ];
+            preConfigure = ''
+              ${prev.preConfigure}
+              rm -r helix-syntax/languages
+              ln -s ${helix}/helix-syntax/languages helix-syntax/languages
+              ln -s "$PWD/helix-syntax/languages" languages
+              mkdir -p runtime/grammars
+            '';
+            postInstall = ''
+              ${prev.postInstall or ""}
+              mkdir -p $out/lib
+              cp -r runtime $out/lib
+              wrapProgram "$out/bin/hx" --set HELIX_RUNTIME "$out/lib/runtime"
+            '';
           };
-          helix-term = prev:
-            let
-              inherit (common) pkgs lib;
-              helixSyntax = lib.buildCrate {
-                root = self;
-                memberName = "helix-syntax";
-                defaultCrateOverrides = {
-                  helix-syntax = helix-syntax;
-                };
-                release = false;
-              };
-              runtimeDir = pkgs.runCommand "helix-runtime" { } ''
-                mkdir -p $out
-                ln -s ${common.root}/runtime/* $out
-                ln -sf ${helixSyntax}/runtime/grammars $out
-              '';
-            in
-            {
-              # link languages and theme toml files since helix-term expects them (for tests)
-              preConfigure = "ln -s ${common.root}/{languages.toml,theme.toml,base16_theme.toml} ..";
-              buildInputs = (prev.buildInputs or [ ]) ++ [ common.cCompiler.cc.lib ];
-              nativeBuildInputs = [ pkgs.makeWrapper ];
-              postFixup = ''
-                if [ -f "$out/bin/hx" ]; then
-                  wrapProgram "$out/bin/hx" --set HELIX_RUNTIME "${runtimeDir}"
-                fi
-              '';
-            };
         };
         shell = common: prev: {
           packages = prev.packages ++ (with common.pkgs; [ lld_13 lldb cargo-tarpaulin cargo-flamegraph ]);