Compiling playground v0.0.1 (/playground) error[E0658]: `match` is not allowed in a `const` --> src/lib.rs:2:17 | 2 | inner: [(); match || {1} { | _________________^ 3 | | n => n(), 4 | | }], | |_____^ | = note: for more information, see https://github.com/rust-lang/rust/issues/49146 = help: add `#![feature(const_if_match)]` to the crate attributes to enable error[E0015]: calls in constants are limited to constant functions, tuple structs and tuple variants --> src/lib.rs:3:14 | 3 | n => n(), | ^^^ error: internal compiler error: src/librustc_typeck/collect.rs:1869: to get the signature of a closure, use `closure_sig()` not `fn_sig()` thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:892:9 stack backtrace: 0: backtrace::backtrace::libunwind::trace at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88 1: backtrace::backtrace::trace_unsynchronized at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/mod.rs:66 2: std::sys_common::backtrace::_print_fmt at src/libstd/sys_common/backtrace.rs:84 3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt at src/libstd/sys_common/backtrace.rs:61 4: core::fmt::write at src/libcore/fmt/mod.rs:1025 5: std::io::Write::write_fmt at src/libstd/io/mod.rs:1426 6: std::sys_common::backtrace::_print at src/libstd/sys_common/backtrace.rs:65 7: std::sys_common::backtrace::print at src/libstd/sys_common/backtrace.rs:50 8: std::panicking::default_hook::{{closure}} at src/libstd/panicking.rs:193 9: std::panicking::default_hook at src/libstd/panicking.rs:210 10: rustc_driver::report_ice 11: std::panicking::rust_panic_with_hook at src/libstd/panicking.rs:475 12: std::panicking::begin_panic 13: rustc_errors::HandlerInner::bug 14: rustc_errors::Handler::bug 15: rustc::util::bug::opt_span_bug_fmt::{{closure}} 16: rustc::ty::context::tls::with_opt::{{closure}} 17: rustc::ty::context::tls::with_opt 18: rustc::util::bug::opt_span_bug_fmt 19: rustc::util::bug::bug_fmt 20: rustc_typeck::collect::fn_sig 21: rustc::ty::query::__query_compute::fn_sig 22: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::fn_sig>::compute 23: rustc::dep_graph::graph::DepGraph::with_task_impl 24: rustc_rayon_core::tlv::with 25: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query 26: rustc::ty::constness::provide::is_const_fn_raw 27: rustc::ty::query::__query_compute::is_const_fn_raw 28: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::is_const_fn_raw>::compute 29: rustc::dep_graph::graph::DepGraph::with_task_impl 30: rustc_rayon_core::tlv::with 31: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query 32: <rustc_mir::const_eval::CompileTimeInterpreter as rustc_mir::interpret::machine::Machine>::find_mir_or_eval_fn 33: rustc_mir::interpret::terminator::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_fn_call 34: rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::step 35: rustc_mir::const_eval::const_eval_raw_provider 36: rustc::ty::query::__query_compute::const_eval_raw 37: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval_raw>::compute 38: rustc::dep_graph::graph::DepGraph::with_task_impl 39: rustc_rayon_core::tlv::with 40: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query 41: rustc_mir::const_eval::const_eval_provider 42: rustc::ty::query::__query_compute::const_eval 43: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute 44: rustc::dep_graph::graph::DepGraph::with_task_impl 45: rustc_rayon_core::tlv::with 46: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query 47: rustc_mir::const_eval::const_eval_provider 48: rustc::ty::query::__query_compute::const_eval 49: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute 50: rustc::dep_graph::graph::DepGraph::with_task_impl 51: rustc_rayon_core::tlv::with 52: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query 53: rustc::ty::sty::Const::eval::{{closure}} 54: <rustc::traits::project::AssocTypeNormalizer as rustc::ty::fold::TypeFolder>::fold_const 55: rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with 56: <rustc::traits::project::AssocTypeNormalizer as rustc::ty::fold::TypeFolder>::fold_ty 57: rustc::traits::project::normalize 58: rustc_typeck::check::FnCtxt::normalize_associated_types_in 59: <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::fold 60: rustc_rayon_core::tlv::with 61: rustc::ty::context::GlobalCtxt::enter_local 62: rustc_typeck::check::wfcheck::check_item_well_formed 63: rustc::ty::query::__query_compute::check_item_well_formed 64: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::check_item_well_formed>::compute 65: rustc::dep_graph::graph::DepGraph::with_task_impl 66: rustc_rayon_core::tlv::with 67: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query 68: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::ensure_query 69: rustc_rayon::iter::plumbing::Producer::fold_with 70: rustc_rayon::iter::plumbing::bridge_producer_consumer::helper 71: rustc_rayon_core::job::StackJob<L,F,R>::run_inline 72: rustc_rayon_core::registry::in_worker 73: rustc_rayon::iter::plumbing::bridge_producer_consumer::helper 74: std::panicking::try::do_call 75: __rust_maybe_catch_panic at src/libpanic_unwind/lib.rs:78 76: <rustc_rayon_core::job::StackJob<L,F,R> as rustc_rayon_core::job::Job>::execute 77: rustc_rayon_core::registry::WorkerThread::wait_until_cold 78: rustc_rayon_core::registry::ThreadBuilder::run 79: scoped_tls::ScopedKey<T>::set 80: std::thread::local::LocalKey<T>::with 81: scoped_tls::ScopedKey<T>::set 82: crossbeam_utils::thread::ScopedThreadBuilder::spawn::{{closure}} 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/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.41.0-nightly (3ed3b8bb7 2019-12-17) running on x86_64-unknown-linux-gnu note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type lib note: some of the compiler flags provided by cargo are hidden query stack during panic: #0 [fn_sig] processing `Bug::inner::{{constant}}#0::{{closure}}#0` #1 [is_const_fn_raw] checking if item is const fn: `Bug::inner::{{constant}}#0::{{closure}}#0` #2 [const_eval_raw] const-evaluating `Bug::inner::{{constant}}#0` #3 [const_eval] const-evaluating + checking `Bug::inner::{{constant}}#0` #4 [const_eval] const-evaluating + checking `Bug::inner::{{constant}}#0` #5 [check_item_well_formed] processing `Bug` #6 [analysis] running analysis passes on this crate end of query stack error: aborting due to 3 previous errors Some errors have detailed explanations: E0015, E0658. For more information about an error, try `rustc --explain E0015`. error: could not compile `playground`.