syntax_data: {"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:         if let SafetyContext::UnsafeBlock { used, span, hir_id, nested_used_blocks } =
context_before:         let safety_context = mem::replace(&mut self.safety_context, prev_context);
context_after:             safety_context