error: internal compiler error: unexpected panic note: the compiler unexpectedly panicked. this is a bug. note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.23.0-nightly (e21df8020 2017-11-13) running on x86_64-apple-darwin note: run with `RUST_BACKTRACE=1` for a backtrace thread 'rustc' panicked at 'explicit panic', src/librustc_typeck/check/cast.rs:110:17 note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. stack backtrace: 0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace 1: std::sys_common::backtrace::_print 2: std::panicking::default_hook::{{closure}} 3: std::panicking::default_hook 4: std::panicking::rust_panic_with_hook 5: std::panicking::begin_panic 6: rustc_typeck::check::cast::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::pointer_kind 7: rustc_typeck::check::cast::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::pointer_kind 8: rustc_typeck::check::cast::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::pointer_kind 9: rustc_typeck::check::cast::CastCheck::check 10: rustc_typeck::check::FnCtxt::check_casts 11: <std::thread::local::LocalKey<T>>::with 12: rustc::ty::context::GlobalCtxt::enter_local 13: _ZN12rustc_typeck5check16typeck_tables_of17h2991cb3aa7f93926E.llvm.5BE90B30 14: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_tables_of<'tcx>>::compute_result 15: _ZN5rustc9dep_graph5graph8DepGraph14with_task_impl17hdc0895b856803ac5E.llvm.E968ED05 16: rustc_errors::Handler::track_diagnostics 17: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::cycle_check 18: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_tables_of<'tcx>>::force 19: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_tables_of<'tcx>>::try_get 20: rustc::ty::maps::TyCtxtAt::typeck_tables_of 21: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_tables_of<'tcx>>::ensure 22: rustc::session::Session::track_errors 23: _ZN12rustc_typeck5check18typeck_item_bodies17h619021d8d31ccdb0E.llvm.5BE90B30 24: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_item_bodies<'tcx>>::compute_result 25: _ZN5rustc9dep_graph5graph8DepGraph14with_task_impl17h09adb0a33cf7a8d7E.llvm.E968ED05 26: rustc_errors::Handler::track_diagnostics 27: rustc::ty::maps::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::cycle_check 28: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_item_bodies<'tcx>>::force 29: rustc::ty::maps::<impl rustc::ty::maps::queries::typeck_item_bodies<'tcx>>::try_get 30: rustc::ty::maps::TyCtxtAt::typeck_item_bodies 31: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::typeck_item_bodies 32: rustc_typeck::check_crate 33: <std::thread::local::LocalKey<T>>::with 34: <std::thread::local::LocalKey<T>>::with 35: rustc::ty::context::TyCtxt::create_and_enter 36: rustc_driver::driver::compile_input 37: rustc_driver::run_compiler