{"ast_node_type":"variable","tokens":[{"end":80,"kind":"keyword","start":0,"text":"let"}]}
            let span = tcx.hir_expect_item(impl_did).expect_impl().self_ty.span;
        Err(ConstParamTyImplementationError::NotAnAdtOrBuiltinAllowed) => {
            Err(tcx.dcx().emit_err(errors::ConstParamTyImplOnNonAdt { span }))