syntax_data: {"ast_node_type":"other","tokens":[{"end":90,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                     // Only deref patterns on boxes can be lowered using a built-in deref.
context_before:                 if cfg!(debug_assertions) && matches!(pattern.kind, PatKind::DerefPattern { .. }) {
context_after:                     debug_assert!(pattern.ty.is_box());