syntax_data: {"ast_node_type":"other","tokens":[{"end":50,"kind":"keyword","start":0,"text":"ProjectionMismatched(ExpectedFound<I::DefId>),"}]}
source_snippet:     ProjectionMismatched(ExpectedFound<I::DefId>),
context_before:     CyclicConst(I::Const),
context_after:     ExistentialMismatch(ExpectedFound<I::BoundExistentialPredicates>),