syntax_data: {"ast_node_type":"other","tokens":[{"end":67,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// `cfg.start_new_block()` or `cfg.start_new_cleanup_block()`.
context_before:     /// Create a new block for the tree. This should call either
context_after:     fn make_block(cfg: &mut CFG<'tcx>) -> BasicBlock;