syntax_data: {"ast_node_type":"other","tokens":[{"end":84,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:                     if ty::ExistentialTraitRef::erase_self_ty(tcx, vtable_principal)
context_before:                         tcx.own_existential_vtable_entries(vtable_principal.def_id).len();
context_after:                         == target_principal