From 677aab11b9dab47907e333fcf666b3056964a7e4 Mon Sep 17 00:00:00 2001
From: Michael-J-Ward <ward.michael.j@gmail.com>
Date: Fri, 6 Sep 2024 14:19:34 -0500
Subject: [PATCH] add toolchain.toml

---
 flake.lock     | 21 +++++++++++++++++++++
 flake.nix      | 19 ++++++++++++++++---
 toolchain.toml |  6 ++++++
 3 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 toolchain.toml

diff --git a/flake.lock b/flake.lock
index 77158bafb..9333b236b 100644
--- a/flake.lock
+++ b/flake.lock
@@ -72,10 +72,31 @@
       "inputs": {
         "flake-parts": "flake-parts",
         "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay",
         "systems": "systems",
         "treefmt-nix": "treefmt-nix"
       }
     },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1724206841,
+        "narHash": "sha256-L8dKaX4T3k+TR2fEHCfGbH4UXdspovz/pj87iai9qmc=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "45e98fbd62c32e5927e952d2833fa1ba4fb35a61",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
     "systems": {
       "locked": {
         "lastModified": 1681028828,
diff --git a/flake.nix b/flake.nix
index 0bdb3a3b2..f9f54dd59 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,6 +2,10 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     flake-parts.url = "github:hercules-ci/flake-parts";
     systems.url = "github:nix-systems/default";
     # Dev tools
@@ -14,8 +18,13 @@
       imports = [
         inputs.treefmt-nix.flakeModule
       ];
-      perSystem = { config, self', pkgs, lib, system, ... }:
+      perSystem = { config, self', lib, system, ... }:
         let
+          pkgs = import inputs.nixpkgs {
+            inherit system;
+            overlays = [ (import inputs.rust-overlay) ];
+            config = { };
+          };
           cargoToml = builtins.fromTOML (builtins.readFile ./Cargo.toml);
           nonRustDeps = [
             pkgs.pkg-config
@@ -27,8 +36,7 @@
           rust-toolchain = python: pkgs.symlinkJoin {
             name = "rust-toolchain";
             paths = [
-              pkgs.rustc
-              pkgs.cargo
+              (pkgs.rust-bin.fromRustupToolchainFile ./toolchain.toml)
               pkgs.clippy
               pkgs.cargo-watch
               pkgs.rust-analyzer
@@ -40,6 +48,11 @@
                 python-pkgs.polars
               ]))
               pkgs.maturin
+              # used for cargo llvm-cov coverage
+              # pkgs.grcov
+              # pkgs.cargo-binutils
+              # pkgs.cargo-llvm-cov
+              # pkgs.rustc.llvmPackages.llvm
             ];
           };
           NIX_LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [
diff --git a/toolchain.toml b/toolchain.toml
new file mode 100644
index 000000000..a09ee20ad
--- /dev/null
+++ b/toolchain.toml
@@ -0,0 +1,6 @@
+# toolchain.toml
+[toolchain]
+channel = "stable"
+components = [ "rustfmt", "rust-src", "llvm-tools" ]
+profile = "default"
+