error: internal compiler error: compiler/rustc_middle/src/ty/sty.rs:78:18: bound region is not anonymous thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9 stack backtrace: 0: std::panicking::begin_panic 1: rustc_errors::HandlerInner::bug 2: rustc_errors::Handler::bug 3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}} 4: rustc_middle::ty::context::tls::with_opt::{{closure}} 5: rustc_middle::ty::context::tls::with_opt 6: rustc_middle::util::bug::opt_span_bug_fmt 7: rustc_middle::util::bug::bug_fmt 8: rustc_middle::ty::sty::BoundRegion::assert_bound_var 9: alloc::collections::btree::map::Entry<K,V>::or_insert_with 10: rustc_middle::ty::fold::<impl rustc_middle::ty::context::TyCtxt>::replace_escaping_bound_vars::{{closure}} 11: <rustc_middle::ty::fold::BoundVarReplacer as rustc_middle::ty::fold::TypeFolder>::fold_region 12: rustc_middle::ty::fold::TypeFoldable::fold_with 13: rustc_middle::ty::structural_impls::<impl rustc_middle::ty::fold::TypeFoldable for &rustc_middle::ty::TyS>::super_fold_with 14: <rustc_middle::ty::fold::BoundVarReplacer as rustc_middle::ty::fold::TypeFolder>::fold_ty 15: rustc_middle::ty::fold::TypeFoldable::fold_with 16: rustc_middle::ty::fold::TypeFoldable::fold_with 17: rustc_middle::ty::fold::TypeFoldable::fold_with 18: rustc_middle::ty::structural_impls::fold_list 19: rustc_middle::ty::fold::<impl rustc_middle::ty::context::TyCtxt>::replace_escaping_bound_vars 20: <rustc_middle::infer::canonical::Canonical<V> as rustc_infer::infer::canonical::substitute::CanonicalExt<V>>::substitute 21: rustc_infer::infer::InferCtxtBuilder::enter_with_canonical 22: rustc_traits::evaluate_obligation::evaluate_obligation 23: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::evaluate_obligation>::compute 24: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl 25: rustc_data_structures::stack::ensure_sufficient_stack 26: rustc_query_system::query::plumbing::get_query_impl 27: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation 28: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation_no_overflow 29: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::predicate_must_hold_modulo_regions 30: rustc_typeck::check::wfcheck::receiver_is_implemented 31: rustc_typeck::check::wfcheck::receiver_is_valid 32: rustc_typeck::check::wfcheck::check_method_receiver 33: rustc_infer::infer::InferCtxtBuilder::enter 34: rustc_typeck::check::wfcheck::check_associated_item 35: rustc_typeck::check::wfcheck::check_trait_item 36: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::check_trait_item_well_formed>::compute 37: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl 38: rustc_data_structures::stack::ensure_sufficient_stack 39: rustc_query_system::query::plumbing::get_query_impl 40: rustc_query_system::query::plumbing::ensure_query_impl 41: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once 42: rustc_hir::hir::Crate::par_visit_all_item_likes 43: rustc_session::session::Session::track_errors 44: rustc_typeck::check_crate 45: rustc_interface::passes::analysis 46: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute 47: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl 48: rustc_data_structures::stack::ensure_sufficient_stack 49: rustc_query_system::query::plumbing::get_query_impl 50: rustc_interface::passes::QueryContext::enter 51: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter 52: rustc_span::with_source_map 53: scoped_tls::ScopedKey<T>::set note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. note: the compiler unexpectedly panicked. this is a bug. note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md note: rustc 1.48.0 (7eac88abb 2020-11-16) running on x86_64-unknown-linux-gnu note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin note: some of the compiler flags provided by cargo are hidden query stack during panic: #0 [evaluate_obligation] evaluating trait selection obligation `&Self: std::ops::Receiver` #1 [check_trait_item_well_formed] checking that `SR::sr` is well-formed #2 [analysis] running analysis passes on this crate end of query stack error: aborting due to 5 previous errors