chore: apply clippy fixes

Author: rich-ayr

bindgen-tests/tests/tests.rs

@@ -27,7 +27,7 @@ fn should_overwrite_expected() -> bool {
             return true;
         }
         assert!(
-            var == "0" || var == "",
+            var == "0" || var.is_empty(),
             "Invalid value of BINDGEN_OVERWRITE_EXPECTED"
         );
     }
@@ -57,7 +57,7 @@ fn error_diff_mismatch(
     if let Some(var) = env::var_os("BINDGEN_TESTS_DIFFTOOL") {
         //usecase: var = "meld" -> You can hand check differences
         let Some(std::path::Component::Normal(name)) =
-            filename.components().last()
+            filename.components().next_back()
         else {
             panic!("Why is the header variable so weird?")
         };
@@ -187,7 +187,7 @@ fn compare_generated_header(
             header.display(),
             looked_at,
         ),
-    };
+    }
 
     let (builder, roundtrip_builder) = builder.into_builder(check_roundtrip)?;
 

bindgen/codegen/mod.rs

@@ -272,7 +272,7 @@ fn format_attribute_tokens(attrs: &[TokenStream]) -> Vec<String> {
                 comments.push(format!(
                     "{}{}",
                     if block_comment_count > 0 { " " } else { "" },
-                    cleaned.to_string()
+                    cleaned
                 ));
             } else if trimmed.starts_with('#') {
                 attrs.push(line.into());