Update the nix build configuration. (#13706)

* Update the nix build configuration.

Remove the old shell.nix with some legacy versions pinned and replace it with a flake-based shell. It installs rust via rustup instead of fenix to be more generally compatible with the guidelines.

This also adds the rust-toolchain.toml spec with all the components required for wasm, and everything else to make rust-analyzer & clippy happy.

* Also add the top level flake for hacking on the substrate as whole

* Remove the envrc and ignore it instead.

* Remove the top-level configuration

---------

Co-authored-by: parity-processbot <>

.gitignore

@@ -26,3 +26,5 @@ rls*.log
 *.iml
 bin/node-template/Cargo.lock
 substrate.code-workspace
+.direnv/
+/.envrc

bin/node-template/.envrc

@@ -0,0 +1 @@
+use flake

bin/node-template/README.md

@@ -153,8 +153,10 @@ Instead of installing dependencies and building this source directly, consider t
 
 ### Nix
 
-Install [nix](https://nixos.org/), and optionally [direnv](https://github.com/direnv/direnv) and [lorri](https://github.com/nix-community/lorri) for a fully plug-and-play experience for setting up the development environment.
-To get all the correct dependencies, activate direnv `direnv allow` and lorri `lorri shell`.
+Install [nix](https://nixos.org/) and
+[nix-direnv](https://github.com/nix-community/nix-direnv) for a fully plug-and-play
+experience for setting up the development environment.
+To get all the correct dependencies, activate direnv `direnv allow`.
 
 ### Docker
 

bin/node-template/flake.nix

@@ -0,0 +1,22 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }: flake-utils.lib.eachDefaultSystem (system:
+    let
+      pkgs = import nixpkgs { inherit system; };
+    in
+    {
+      devShells.default = pkgs.mkShell {
+        packages = with pkgs; [
+          rustup
+          clang
+          protobuf
+        ];
+
+        LIBCLANG_PATH = "${pkgs.libclang.lib}/lib";
+      };
+    });
+}

bin/node-template/rust-toolchain.toml

@@ -0,0 +1,14 @@
+[toolchain]
+channel = "nightly"
+components = [
+	"cargo",
+	"clippy",
+	"rust-analyzer",
+	"rust-src",
+	"rust-std",
+	"rustc-dev",
+	"rustc",
+	"rustfmt",
+]
+targets = [ "wasm32-unknown-unknown" ]
+profile = "minimal"