Use #[expect(lint)] over #[allow(lint)] where possible (#17822)

crates/ruff_source_file/src/line_index.rs

@@ -43,7 +43,7 @@ impl LineIndex {
                 b'\r' if bytes.get(i + 1) == Some(&b'\n') => continue,
                 b'\n' | b'\r' => {
                     // SAFETY: Assertion above guarantees `i <= u32::MAX`
-                    #[allow(clippy::cast_possible_truncation)]
+                    #[expect(clippy::cast_possible_truncation)]
                     line_starts.push(TextSize::from(i as u32) + TextSize::from(1));
                 }
                 _ => {}

crates/ruff_source_file/src/newlines.rs

@@ -322,7 +322,7 @@ impl LineEnding {
         }
     }
 
-    #[allow(clippy::len_without_is_empty)]
+    #[expect(clippy::len_without_is_empty)]
     pub const fn len(&self) -> usize {
         match self {
             LineEnding::Lf | LineEnding::Cr => 1,