flake: use builtins.fetchTree to shallow-clone grammar repos

Here we perform a shallow fetch using builtins.fetchTree. In order
to make this work, we need to specify the `ref' for any repository
that doesn't have `master' as its default branch (I'm not sure why
this limitation exists since we don't need this when performing
the shallow fetch in `--grammar build')

This `ref' field is ignored by helix, so I have left it undocumented
for now, but I could be open to documenting it.

flake.lock

@@ -25,11 +25,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1646322147,
-        "narHash": "sha256-XwrdjThHPq/APV7B6mXJwYvN/3RmsjX1W4zPgjvCp0A=",
+        "lastModified": 1646667754,
+        "narHash": "sha256-LahZHvCC3UVzGQ55iWDRZkuDssXl1rYgqgScrPV9S38=",
         "owner": "numtide",
         "repo": "devshell",
-        "rev": "2cc45675b223a35ca1d8af6383752c3d4b66f484",
+        "rev": "59fbe1dfc0de8c3332957c16998a7d16dff365d8",
         "type": "github"
       },
       "original": {
@@ -75,11 +75,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1646647374,
-        "narHash": "sha256-sFGoE9LbHfP5t8NGcNkX4sPVq9kp8+ae8ODnW5eOkzo=",
+        "lastModified": 1646710334,
+        "narHash": "sha256-eLBcDgcbOUfeH4k6SEW5a5v0PTp2KNCn+5ZXIoWGYww=",
         "owner": "nix-community",
         "repo": "dream2nix",
-        "rev": "76412363073ea1252700eb48901849cf8480e138",
+        "rev": "5dcfbfd3b60ce0208b894c1bdea00e2bdf80ca6a",
         "type": "github"
       },
       "original": {
@@ -119,24 +119,6 @@
         "type": "github"
       }
     },
-    "helix": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1646500939,
-        "narHash": "sha256-M0QvrRuluDkBWUfd5CYwvj9WtgalKlm5stJUAwnhrwI=",
-        "ref": "master",
-        "rev": "7633c5acd30258fc9caca926bfaa264d07d508ec",
-        "revCount": 2438,
-        "submodules": true,
-        "type": "git",
-        "url": "https://github.com/helix-editor/helix.git"
-      },
-      "original": {
-        "submodules": true,
-        "type": "git",
-        "url": "https://github.com/helix-editor/helix.git"
-      }
-    },
     "nixCargoIntegration": {
       "inputs": {
         "devshell": "devshell",
@@ -149,11 +131,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1646681124,
-        "narHash": "sha256-1ytR1z6RyBbxhk0LiO18QBH6Mu1JfAEWuUVBdbD4Bw8=",
+        "lastModified": 1646766572,
+        "narHash": "sha256-DV3+zxvAIKsMHsHedJKYFsracvFyLKpFQqurUBR86oY=",
         "owner": "yusdacra",
         "repo": "nix-cargo-integration",
-        "rev": "3b08d21177cecd5d69bdf76400a6145a021d1e49",
+        "rev": "3a3f47f43ba486b7554164a698c8dfc5a38624ce",
         "type": "github"
       },
       "original": {
@@ -164,11 +146,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1646254136,
-        "narHash": "sha256-8nQx02tTzgYO21BP/dy5BCRopE8OwE8Drsw98j+Qoaw=",
+        "lastModified": 1646497237,
+        "narHash": "sha256-Ccpot1h/rV8MgcngDp5OrdmLTMaUTbStZTR5/sI7zW0=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "3e072546ea98db00c2364b81491b893673267827",
+        "rev": "062a0c5437b68f950b081bbfc8a699d57a4ee026",
         "type": "github"
       },
       "original": {
@@ -180,7 +162,6 @@
     },
     "root": {
       "inputs": {
-        "helix": "helix",
         "nixCargoIntegration": "nixCargoIntegration",
         "nixpkgs": "nixpkgs",
         "rust-overlay": "rust-overlay"
@@ -194,11 +175,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1642128126,
-        "narHash": "sha256-av8JUACdrTfQYl/ftZJvKpZEmZfa0avCq7tt5Usdoq0=",
+        "lastModified": 1646792695,
+        "narHash": "sha256-2drCXIKIQnJMlTZbcCfuHZAh+iPcdlRkCqtZnA6MHLY=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "ce4ef6f2d74f2b68f7547df1de22d1b0037ce4ad",
+        "rev": "7f599870402c8d2a5806086c8ee0f2d92b175c54",
         "type": "github"
       },
       "original": {

flake.nix

@@ -12,17 +12,9 @@
       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@{ nixCargoIntegration, helix, ... }:
+  outputs = inputs@{ nixCargoIntegration, ... }:
     nixCargoIntegration.lib.makeOutputs {
       root = ./.;
       renameOutputs = { "helix-term" = "helix"; };

grammars.nix

@@ -13,10 +13,12 @@ let
   gitGrammars = builtins.filter isGitGrammar languagesConfig.grammar;
   buildGrammar = grammar:
     let
-      source = builtins.fetchGit {
+      source = builtins.fetchTree {
+        type = "git";
         url = grammar.source.git;
         rev = grammar.source.rev;
-        allRefs = true;
+        ref = grammar.source.ref or "HEAD";
+        shallow = true;
       };
     in stdenv.mkDerivation rec {
       # see https://github.com/NixOS/nixpkgs/blob/fbdd1a7c0bc29af5325e0d7dd70e804a972eb465/pkgs/development/tools/parsing/tree-sitter/grammar.nix