feat: highlight tail expr when cursor is on label

Author: roife

src/tools/rust-analyzer/crates/ide/src/highlight_related.rs

@@ -232,6 +232,23 @@ fn highlight_references(
             }
         }
 
+        // highlight the tail expr of the labelled block
+        if matches!(def, Definition::Label(_)) {
+            let label = token.parent_ancestors().nth(1).and_then(ast::Label::cast);
+            if let Some(block) =
+                label.and_then(|label| label.syntax().parent()).and_then(ast::BlockExpr::cast)
+            {
+                for_each_tail_expr(&block.into(), &mut |tail| {
+                    if !matches!(tail, ast::Expr::BreakExpr(_)) {
+                        res.insert(HighlightedRange {
+                            range: tail.syntax().text_range(),
+                            category: ReferenceCategory::empty(),
+                        });
+                    }
+                });
+            }
+        }
+
         // highlight the defs themselves
         match def {
             Definition::Local(local) => {
@@ -2098,6 +2115,26 @@ fn foo() {
      // ^
     }
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn labeled_block_tail_expr_2() {
+        check(
+            r#"
+fn foo() {
+    let _ = 'b$0lk: {
+         // ^^^^
+        let x = 1;
+        if true { break 'blk 42; }
+                     // ^^^^
+        if false { break 'blk 24; }
+                      // ^^^^
+        100
+     // ^^^
+    };
+}
 "#,
         );
     }