syntax_data: {"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"PatKind::ExpandedConstant"}]}
source_snippet:                 PatKind::ExpandedConstant { ref subpattern, def_id: _ }
context_before:                 PatKind::Constant { value } => value,
context_after:                     if let PatKind::Constant { value } = subpattern.kind =>