syntax_data: {"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"mapped_regions:"}]}
source_snippet:         mapped_regions: FxIndexMap<ty::PlaceholderRegion, ty::BoundRegion>,
context_before:         infcx: &'a InferCtxt<'tcx>,
context_after:         mapped_types: FxIndexMap<ty::PlaceholderType, ty::BoundTy>,