syntax_data: {"ast_node_type":"other","tokens":[{"end":58,"kind":"keyword","start":0,"text":"//"}]}
source_snippet: // for `Supertrait`'s methods in the vtable of `Subtrait`.
context_before: // Given a `dyn Subtrait: Supertrait` trait ref, find corresponding first slot
context_after: pub(crate) fn first_method_vtable_slot<'tcx>(tcx: TyCtxt<'tcx>, key: ty::TraitRef<'tcx>) -> usize {