message: Use `devShells` key in flake, where appropriate
diff: # Crate containing the `fathom` binary
  crateName = "fathom";
  # TODO: find the manifest for ${crateName} in the workspace
  - # minRustVersion = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).package.rust-version;
  - minRustVersion = "1.56.0";
  + # minimumRustVersion = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).package.rust-version;
  + minimumRustVersion = "1.56.0";
  # Setup Rust toolchains to build and test against
  rust = {
  nightly = pkgs.rust-bin.nightly.latest.minimal;
  stable = pkgs.rust-bin.stable.latest.minimal;
  - minimum = pkgs.rust-bin.stable.${minRustVersion}.minimal;
  + minimum = pkgs.rust-bin.stable.${minimumRustVersion}.minimal;
  };
  # Override Naersk with the MSRV version of Rust
  # stable = naersk.lib."${system}".override { cargo = rust.stable; rustc = rust.stable; };
  minimum = naersk.lib."${system}".override { cargo = rust.minimum; rustc = rust.minimum; };
  };
  -
  - # Creates a development shell using a specific version of Rust
  - createShell = { rust }: pkgs.mkShell {
  - packages = [ (rust.override { extensions = [ "rust-src" "rustfmt" ]; }) ];
  - # Certain tools like `rust-analyzer` won't work without this
  - RUST_SRC_PATH = "${rust}/lib/rustlib/src/rust/library";
  - };
  in
  {
  # Executed by `nix flake check`
  defaultApp = self.apps.${system}.${crateName};
  - # Use `nix develop .#stableShell` to enter each dev env.
  - packages.nightlyShell = createShell { rust = rust.nightly; };
  - packages.stableShell = createShell { rust = rust.stable; };
  - packages.minimumShell = createShell { rust = rust.minimum; };
  + # Used by `nix develop .#<name>`
  + devShells = (
  + let
  + # Creates a development shell using a specific Rust toolchain
  + createShell = { rust }: pkgs.mkShell {
  + packages = [ (rust.override { extensions = [ "rust-src" "rustfmt" ]; }) ];
  + # Certain tools like `rust-analyzer` won't work without this
  + RUST_SRC_PATH = "${rust}/lib/rustlib/src/rust/library";
  + };
  + in
  + {
  + nightly = createShell { rust = rust.nightly; };
  + stable = createShell { rust = rust.stable; };
  + minimum = createShell { rust = rust.minimum; };
  + }
  + );
  # Used by `nix develop`
  - devShell = self.packages.${system}.stableShell;
  + devShell = self.devShells.${system}.stable;
  }
  );
  }
  