chore: fix clippy warnings

src/lib.rs

@@ -828,13 +828,13 @@ fn to_doc<'a>(
                     Rule::COMMENT => {
                         inner = inner.append(doc);
                     }
-                    rule @ _ => unreachable!("Unreachable rule {rule:?}"),
+                    rule => unreachable!("Unreachable rule {rule:?}"),
                 }
             }
             arena.space().append(block_braces(
                 arena,
                 inner,
-                pairs.rev().next().unwrap().as_rule() == Rule::semi_str,
+                pairs.last().unwrap().as_rule() == Rule::semi_str,
             ))
         }
         Rule::calc_macro_call => map_to_doc(ctx, arena, pair),

src/rustfmt.rs

@@ -25,20 +25,14 @@ pub fn rustfmt(s: &str) -> Option<String> {
 }
 
 /// Options to pass to `rustfmt`
-#[derive(Clone)]
+#[derive(Clone, Default)]
 pub struct RustFmtConfig {
     /// If set, explicitly provides the specified `rustfmt.toml` configuration to rustfmt;
     /// otherwise, uses the default behavior (i.e., picking up `rustfmt.toml` if it exists from
     /// the file's directory or ancestors)
     pub rustfmt_toml: Option<String>,
 }
 
-impl Default for RustFmtConfig {
-    fn default() -> Self {
-        Self { rustfmt_toml: None }
-    }
-}
-
 impl RustFmtConfig {
     pub fn run(&self, s: &str) -> Option<String> {
         rustfmt_with_config(s, self)