CI: introduce first CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,64 @@
+name: "Rust checks"
+
+on:
+  pull_request:
+    branches: [ main ]
+
+permissions:
+  contents: read
+  actions: read
+
+jobs:
+  check:
+    # Target self-hosted runner by label
+    runs-on: [ nixos ]
+
+    # SECURITY: Require manual approval for external PRs
+    if: ${{ github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository }}
+
+    steps:
+      - name: checkout-code
+        uses: actions/checkout@v4
+
+      - name: cargo-check
+        env:
+          RUSTFLAGS: "-D warnings" # Make all warnings deny.
+        run: nix develop --command cargo check
+
+      - name: cargo-test
+        env:
+          RUSTFLAGS: "-D warnings" # Make all warnings deny.
+        run: nix develop --command cargo test
+
+      # TODO: make clippy work
+      # - name: cargo-clippy
+      #   env:
+      #     RUSTFLAGS: "-D warnings" # Make all warnings deny.
+      #   run: nix develop --command cargo clippy
+
+      - name: cargo-bench
+        run: nix develop --command cargo bench --no-run # Just to make sure it compiles
+
+      - name: cargo-fmt
+        run: nix develop --command cargo fmt --check
+
+      - name: cargo-doc
+        run: nix develop --command cargo doc
+
+      - name: nix-flake-check
+        run: nix flake check
+
+      - name: nix-deadnix
+        run: nix develop --command deadnix
+
+      - name: nix-statix
+        run: nix develop --command statix check
+
+      - name: nix-alejandra
+        run: nix develop --command alejandra --check .
+
+      # TODO: enable hongdown
+      # - name: markdown-formatting
+      #   run: nix develop --command hongdown --check .
+
+

flake.nix

@@ -55,7 +55,6 @@
         with pkgs; {
           devShells.default = mkShell {
             buildInputs = [
-              (lib.hiPrio rust-bin.nightly."2025-02-01".rustfmt)
               rust
               cargo-nextest
               cargo-semver-checks
@@ -64,7 +63,10 @@
               cargo-tarpaulin # Code coverage
               cargo-audit
               cargo-machete
-              taplo
+              taplo # Format `.toml` files.
+              deadnix # Nix dead code checker
+              alejandra # Nix code formatter.
+              statix # Nix static code checker.
               mprocs # Run multiple commands in parallel from `mprocs.yml`, acting essentially as a local CI system.
               hongdown.packages.${system}.hongdown
               creusot # Execute with `cargo creusot`