syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"ImplSource::Builtin(BuiltinImplSource::Misc,"}]}
source_snippet:                 ImplSource::Builtin(BuiltinImplSource::Misc, PredicateObligations::new())
context_before:             AsyncFnKindHelperCandidate => {
context_after:             }