syntax_data: {"ast_node_type":"other","tokens":[{"end":42,"kind":"keyword","start":0,"text":"block_data:"}]}
source_snippet:     block_data: &mut BasicBlockData<'tcx>,
context_before:     local_decls: &mut IndexVec<Local, LocalDecl<'tcx>>,
context_after:     source_op: Operand<'tcx>,