syntax_data: {"ast_node_type":"other","tokens":[{"end":108,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                     // That block is already unreachable but needs a terminator to make the MIR well-formed.
context_before:                     let block = subcandidate.pre_binding_block.unwrap();
context_after:                     let source_info = self.source_info(subcandidate.extra_data.span);