Fix clippy issue & add fmt check

.github/workflows/build.yml

@@ -23,11 +23,27 @@ jobs:
       - name: Setup Rust toolchain
         uses: dtolnay/rust-toolchain@stable
         with:
-          components: rustfmt, clippy
+          components: clippy
       - name: Cargo check
-        run: cargo check --all-features
+        run: cargo check --all-features --all-targets
       - name: Cargo clippy
-        run: cargo clippy --all-features
+        run: cargo clippy --all-features --all-targets
+
+  fmt:
+    name: Format
+    runs-on: ubuntu-latest
+    env:
+      RUSTFLAGS: -D warnings
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Setup Rust toolchain
+        # We use nightly options in rustfmt.toml
+        uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: rustfmt
+      - name: Cargo fmt
+        run: cargo fmt --all --check
 
   deny:
     name: Deny

src/main.rs

@@ -48,7 +48,7 @@ impl ToString for LogLevel {
 impl FromArgValue for LogLevel {
     fn from_arg_value(value: &OsStr) -> Result<Self, String> {
         String::from_arg_value(value)
-            .and_then(|s| Self::from_str(&s).map_err(|_| format!("Invalid log level")))
+            .and_then(|s| Self::from_str(&s).map_err(|_| "Invalid log level".to_string()))
     }
 }