syntax_data: {"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"[first"}]}
source_snippet:                         [first @ last] | [first, .., last] => dcx
context_before:                         },
context_after:                             .emit_fatal(LoopMatchBadStatements { span: first.span.to(last.span) }),