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:                 VtblSegment::TraitOwnEntries { trait_ref: vtable_principal, emit_vptr } => {
context_after:                         == target_principal