syntax_data: {"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":"target:"}]}
source_snippet:     target: &crate::spec::Target,
context_before:     target_features: &FxIndexSet<Symbol>,
context_after: ) -> FxHashMap<InlineAsmRegClass, FxIndexSet<InlineAsmReg>> {