Fix 🦶🔫: Validate visitNonNull arguments (#4016)

I often find myself shooting myself in the foot passing the wrong `Cursor` to `visitNonNull`. This is a very easy mistake to make and often leads to quite a bit of confusion. This fixes that by validating that a parent cursor is being passed, not the current cursor. Signed-off-by: Jonathan Leitschuh <[email protected]>
openrewrite · Feb 19, 2024 · b077208 · b077208
1 parent dd77edd
commit b077208
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/rewrite-core/src/main/java/org/openrewrite/TreeVisitor.java b/rewrite-core/src/main/java/org/openrewrite/TreeVisitor.java
@@ -200,6 +200,11 @@ public T visitNonNull(Tree tree, P p) {
     }
 
     public T visitNonNull(Tree tree, P p, Cursor parent) {
+        if (parent.getValue() instanceof Tree && ((Tree) parent.getValue()).isScope(tree)) {
+            throw new IllegalArgumentException(
+                    "The `parent` cursor must not point to the same `tree` as the tree to be visited"
+            );
+        }
         T t = visit(tree, p, parent);
         assert t != null;
         return t;