feat(tools/depotfmt): add a treefmt wrapper with depot configuration r/3295

Right now the only included formatter is gofmt, but we will extend
this over time.

The version of treefmt is bumped to 0.3.0 (which supports custom
config files) until this lands in nixpkgs.

Change-Id: I1e1aafd05ec7427c616f90c90490c528ecb2615c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4399
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>

4 files changed, 37 insertions, 0 deletions

diff --git a/bin/__dispatch.sh b/bin/__dispatch.sh
index c4d8b5991987..6eb24beaf5c6 100755
--- a/bin/__dispatch.sh
+++ b/bin/__dispatch.sh
@@ -58,6 +58,9 @@ case "${TARGET_TOOL}" in
   stern)
     attr="third_party.nixpkgs.stern"
     ;;
+  depotfmt)
+    attr="tools.depotfmt"
+    ;;
   *)
     echo "The tool '${TARGET_TOOL}' is currently not installed in this repository."
     exit 1
diff --git a/bin/depotfmt b/bin/depotfmt
new file mode 120000
index 000000000000..8390ec9c9652
--- /dev/null
+++ b/bin/depotfmt
@@ -0,0 +1 @@
+__dispatch.sh
\ No newline at end of file
diff --git a/third_party/overlays/tvl.nix b/third_party/overlays/tvl.nix
index 80f337200176..df21e8819bbe 100644
--- a/third_party/overlays/tvl.nix
+++ b/third_party/overlays/tvl.nix
@@ -59,4 +59,21 @@ self: super: {
   mkShell = super.lib.makeOverridable(args: (super.mkShell args) // {
     meta.ci = false;
   });
+
+  # bump treefmt to a newer version that includes our config file patch
+  treefmt = super.treefmt.overrideAttrs(drv: rec {
+    version = "0.3.0";
+
+    src = super.fetchFromGitHub {
+      owner = "numtide";
+      repo = "treefmt";
+      rev = "v${version}";
+      sha256 = "0jnfak6wmqpqwymja9bsw54al50yqzdy7lxfx66rqamqsvngqd1x";
+    };
+
+    cargoDeps = drv.cargoDeps.overrideAttrs(_: {
+      inherit src;
+      outputHash = "19p15gavcjldn1di7yyn80ys6rj4ajaprqk8x34vxslr4y2qychf";
+    });
+  });
 }
diff --git a/tools/depotfmt.nix b/tools/depotfmt.nix
new file mode 100644
index 000000000000..097bc29b4595
--- /dev/null
+++ b/tools/depotfmt.nix
@@ -0,0 +1,16 @@
+# Builds treefmt for depot, with a hardcoded configuration that
+# includes the right paths to formatters.
+{ pkgs, ... }:
+
+let
+  config = pkgs.writeText "depot-treefmt-config" ''
+    [formatter.go]
+    command = "${pkgs.go}/bin/gofmt"
+    options = [ "-w" ]
+    includes = ["*.go"]
+  '';
+in pkgs.writeShellScriptBin "depotfmt" ''
+  exec ${pkgs.treefmt}/bin/treefmt ''${@} \
+    --config-file ${config} \
+    --tree-root $(${pkgs.git}/bin/git rev-parse --show-toplevel)
+''