syntax_data: {"ast_node_type":"other","tokens":[{"end":54,"kind":"keyword","start":0,"text":"default_mode_labels:"}]}
source_snippet:     default_mode_labels: FxIndexMap<Span, Mutability>,
context_before:     // labels will be wrong.
context_after:     /// Information collected from typeck, including spans for subpatterns invalid in Rust 2024.