invalid syntax (unclosed brace) yields eventual ICE: unexpected ty: [type error]

[DutchGhost]

The following ICE's on stable, beta and nightly:

use std::marker::PhantomData;

enum Bug {
    V = [PhantomData; { [ () ].len() ].len() as isize,
    //                ^
    //                + ---- this brace is never closed!!!
}

(notice the { was NOT closed)

Backtrace:

error: incorrect close delimiter: `]`
 --> src/lib.rs:4:38
  |
4 |     V = [PhantomData; { [ () ].len() ].len() as isize,
  |         -             -              ^ incorrect close delimiter
  |         |             |
  |         |             un-closed delimiter
  |         close delimiter possibly meant for this

error: internal compiler error: src/librustc_mir/hair/cx/expr.rs:954: unexpected ty: [type error]

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:812:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:76
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:60
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1030
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1412
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:64
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:196
   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:477
  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_context_opt
  18: rustc::ty::context::tls::with_opt
  19: rustc::util::bug::opt_span_bug_fmt
  20: rustc::util::bug::bug_fmt
  21: rustc_mir::hair::cx::expr::make_mirror_unadjusted
  22: rustc_mir::hair::cx::expr::<impl rustc_mir::hair::Mirror for &rustc::hir::Expr>::make_mirror
  23: <rustc_mir::hair::ExprRef as rustc_mir::hair::Mirror>::make_mirror
  24: rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue
  25: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  26: rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp
  27: rustc_mir::build::expr::as_place::<impl rustc_mir::build::Builder>::expr_as_place
  28: rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue
  29: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  30: rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp
  31: rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand
  32: rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue
  33: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  34: rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp
  35: rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand
  36: rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand
  37: rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::as_local_operand
  38: <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
  39: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T,I>>::from_iter
  40: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  41: rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp
  42: rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand
  43: rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand
  44: rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue
  45: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  46: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  47: rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr
  48: rustc_mir::build::construct_const
  49: rustc::ty::context::tls::with_context::{{closure}}
  50: rustc_mir::build::mir_build
  51: rustc_mir::transform::mir_built
  52: rustc::ty::query::__query_compute::mir_built
  53: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_built>::compute
  54: rustc::dep_graph::graph::DepGraph::with_task_impl
  55: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  56: rustc_mir::transform::check_unsafety::unsafety_check_result
  57: rustc::ty::query::__query_compute::unsafety_check_result
  58: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::unsafety_check_result>::compute
  59: rustc::dep_graph::graph::DepGraph::with_task_impl
  60: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  61: rustc_mir::transform::mir_const
  62: rustc::ty::query::__query_compute::mir_const
  63: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_const>::compute
  64: rustc::dep_graph::graph::DepGraph::with_task_impl
  65: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  66: rustc_mir::transform::qualify_consts::mir_const_qualif
  67: rustc::ty::query::__query_compute::mir_const_qualif
  68: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_const_qualif>::compute
  69: rustc::dep_graph::graph::DepGraph::with_task_impl
  70: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  71: rustc_mir::transform::mir_validated
  72: rustc::ty::query::__query_compute::mir_validated
  73: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_validated>::compute
  74: rustc::dep_graph::graph::DepGraph::with_task_impl
  75: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  76: rustc_mir::borrow_check::mir_borrowck
  77: rustc::ty::query::__query_compute::mir_borrowck
  78: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_borrowck>::compute
  79: rustc::dep_graph::graph::DepGraph::with_task_impl
  80: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  81: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::ensure_query
  82: rustc_mir::transform::optimized_mir
  83: rustc::ty::query::__query_compute::optimized_mir
  84: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::optimized_mir>::compute
  85: rustc::dep_graph::graph::DepGraph::with_task_impl
  86: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  87: rustc_mir::interpret::eval_context::InterpCx<M>::load_mir
  88: rustc_mir::const_eval::const_eval_raw_provider
  89: rustc::ty::query::__query_compute::const_eval_raw
  90: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval_raw>::compute
  91: rustc::dep_graph::graph::DepGraph::with_task_impl
  92: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  93: rustc_mir::const_eval::const_eval_provider
  94: rustc::ty::query::__query_compute::const_eval
  95: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute
  96: rustc::dep_graph::graph::DepGraph::with_task_impl
  97: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  98: <rustc_typeck::collect::CollectItemTypesVisitor as rustc::hir::intravisit::Visitor>::visit_item
  99: rustc::hir::map::Map::visit_item_likes_in_module
 100: rustc_typeck::collect::collect_mod_item_types
 101: rustc::ty::query::__query_compute::collect_mod_item_types
 102: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::collect_mod_item_types>::compute
 103: rustc::dep_graph::graph::DepGraph::with_task_impl
 104: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
 105: rustc_typeck::check_crate::{{closure}}::{{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 1.39.0 (4560ea788 2019-11-04) 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:
thread 'rustc' panicked at 'already borrowed: BorrowMutError', src/libcore/result.rs:1165:5
stack backtrace:
   0:     0x7fe468c4daf4 - backtrace::backtrace::libunwind::trace::hda41dbcdfba36aa0
                               at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/libunwind.rs:88
   1:     0x7fe468c4daf4 - backtrace::backtrace::trace_unsynchronized::h1a8d6e1f8cb3f5d4
                               at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/mod.rs:66
   2:     0x7fe468c4daf4 - std::sys_common::backtrace::_print_fmt::h610c4127487e10da
                               at src/libstd/sys_common/backtrace.rs:76
   3:     0x7fe468c4daf4 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h0722dc552e01bd1d
                               at src/libstd/sys_common/backtrace.rs:60
   4:     0x7fe468c8612c - core::fmt::write::h01edf6dd68a42c9c
                               at src/libcore/fmt/mod.rs:1030
   5:     0x7fe468c41d17 - std::io::Write::write_fmt::hf15985f193f03c04
                               at src/libstd/io/mod.rs:1412
   6:     0x7fe468c52325 - std::sys_common::backtrace::_print::hd8d5d08a1795e743
                               at src/libstd/sys_common/backtrace.rs:64
   7:     0x7fe468c52325 - std::sys_common::backtrace::print::hf89a79e3921a2366
                               at src/libstd/sys_common/backtrace.rs:49
   8:     0x7fe468c52325 - std::panicking::default_hook::{{closure}}::h3a8f42beb3bb8ae3
                               at src/libstd/panicking.rs:196
   9:     0x7fe468c52016 - std::panicking::default_hook::h8f803b0bc31a5c37
                               at src/libstd/panicking.rs:210
  10:     0x7fe469189483 - rustc_driver::report_ice::he98718c53edc6d3d
  11:     0x7fe468c52b0c - std::panicking::rust_panic_with_hook::h825f041245da8739
                               at src/libstd/panicking.rs:477
  12:     0x7fe468c525c2 - std::panicking::continue_panic_fmt::hbe0378e33481e81b
                               at src/libstd/panicking.rs:380
  13:     0x7fe468c524b6 - rust_begin_unwind
                               at src/libstd/panicking.rs:307
  14:     0x7fe468c7faca - core::panicking::panic_fmt::h527855ce0bc891f6
                               at src/libcore/panicking.rs:85
  15:     0x7fe468c7fd07 - core::result::unwrap_failed::ha8b77e6004f0ba38
                               at src/libcore/result.rs:1165
  16:     0x7fe46af64fe5 - rustc_errors::Handler::force_print_diagnostic::h807dd1aae3e0d79e
  17:     0x7fe46a837d91 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::try_print_query_stack::h8734d6360e0a8b59
  18:     0x7fe46918a095 - rustc_driver::report_ice::he98718c53edc6d3d
  19:     0x7fe468c52b0c - std::panicking::rust_panic_with_hook::h825f041245da8739
                               at src/libstd/panicking.rs:477
  20:     0x7fe46af4c37d - std::panicking::begin_panic::h577649efa65d7301
  21:     0x7fe46af65743 - rustc_errors::HandlerInner::bug::hfd27cc932b37506a
  22:     0x7fe46af6462a - rustc_errors::Handler::bug::h32e2ca63254dbbec
  23:     0x7fe46a7f48c3 - rustc::util::bug::opt_span_bug_fmt::{{closure}}::hf2652d3cbc7068ac
  24:     0x7fe46a7ef933 - rustc::ty::context::tls::with_opt::{{closure}}::h0fe4f06c0a285fde
  25:     0x7fe46a7ef8a3 - rustc::ty::context::tls::with_context_opt::h01f88b941c2d3d77
  26:     0x7fe46a7ef8e7 - rustc::ty::context::tls::with_opt::hac6f601ca34cd941
  27:     0x7fe46a7f47d8 - rustc::util::bug::opt_span_bug_fmt::h234c815c9e7b30ef
  28:     0x7fe46a7f4742 - rustc::util::bug::bug_fmt::hca65a18e8bb5d55b
  29:     0x7fe469a93b38 - rustc_mir::hair::cx::expr::make_mirror_unadjusted::h79bf17834410ceb8
  30:     0x7fe469a8f72c - rustc_mir::hair::cx::expr::<impl rustc_mir::hair::Mirror for &rustc::hir::Expr>::make_mirror::h452fbd6128897835
  31:     0x7fe469dbccf6 - <rustc_mir::hair::ExprRef as rustc_mir::hair::Mirror>::make_mirror::h61b3e2926ecd55dc
  32:     0x7fe469d18b31 - rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue::hc76b26c7f9e16661
  33:     0x7fe469d1e9f1 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  34:     0x7fe469d1e3c2 - rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp::h6c83785bfcea8b3f
  35:     0x7fe469d1696a - rustc_mir::build::expr::as_place::<impl rustc_mir::build::Builder>::expr_as_place::h930a7c2b5286e31d
  36:     0x7fe469d18d36 - rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue::hc76b26c7f9e16661
  37:     0x7fe469d1e9f1 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  38:     0x7fe469d1e3c2 - rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp::h6c83785bfcea8b3f
  39:     0x7fe469d1632b - rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand::h1c23cb59c441f03b
  40:     0x7fe469d19fd1 - rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue::hc76b26c7f9e16661
  41:     0x7fe469d1e9f1 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  42:     0x7fe469d1e3c2 - rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp::h6c83785bfcea8b3f
  43:     0x7fe469d1632b - rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand::h1c23cb59c441f03b
  44:     0x7fe469d1661f - rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand::h1c23cb59c441f03b
  45:     0x7fe469d16174 - rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::as_local_operand::hf3e609ce62beae87
  46:     0x7fe469eaac7c - <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::fold::hda7386db639cd944
  47:     0x7fe4699e3601 - <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T,I>>::from_iter::h205999cfb2ee670d
  48:     0x7fe469d202e5 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  49:     0x7fe469d1e3c2 - rustc_mir::build::expr::as_temp::<impl rustc_mir::build::Builder>::expr_as_temp::h6c83785bfcea8b3f
  50:     0x7fe469d1632b - rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand::h1c23cb59c441f03b
  51:     0x7fe469d1661f - rustc_mir::build::expr::as_operand::<impl rustc_mir::build::Builder>::expr_as_operand::h1c23cb59c441f03b
  52:     0x7fe469d1a148 - rustc_mir::build::expr::as_rvalue::<impl rustc_mir::build::Builder>::expr_as_rvalue::hc76b26c7f9e16661
  53:     0x7fe469d1e9f1 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  54:     0x7fe469d21208 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  55:     0x7fe469d21208 - rustc_mir::build::expr::into::<impl rustc_mir::build::Builder>::into_expr::h433aa4de00655726
  56:     0x7fe469d11df9 - rustc_mir::build::construct_const::h4a50cf498b0aaef6
  57:     0x7fe469b92bda - rustc::ty::context::tls::with_context::{{closure}}::hdbc49d28b4e3fc8d
  58:     0x7fe469d0fbc1 - rustc_mir::build::mir_build::h9b6a0d508efaccdf
  59:     0x7fe469af3751 - rustc_mir::transform::mir_built::h93b4d3d38d69c498
  60:     0x7fe469bec2d7 - rustc::ty::query::__query_compute::mir_built::h5ad6fc235bbbc440
  61:     0x7fe469b0a4ab - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_built>::compute::hd0251bf1e87724b2
  62:     0x7fe469c5652a - rustc::dep_graph::graph::DepGraph::with_task_impl::haf54122c0853cacb
  63:     0x7fe469b70b05 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::hcee602b1e4eb3310
  64:     0x7fe469e5ac26 - rustc_mir::transform::check_unsafety::unsafety_check_result::h36f3ad2c6f7e0e43
  65:     0x7fe469beb212 - rustc::ty::query::__query_compute::unsafety_check_result::h4fba89e0308db7b5
  66:     0x7fe469b0a99c - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::unsafety_check_result>::compute::h818a47e9622a43fd
  67:     0x7fe469c4e505 - rustc::dep_graph::graph::DepGraph::with_task_impl::h3b616150987f9c12
  68:     0x7fe469b5e553 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h9bd9dbc611fc1a2a
  69:     0x7fe469af4919 - rustc_mir::transform::mir_const::h12e0a05cddb3b5e7
  70:     0x7fe469bec3b7 - rustc::ty::query::__query_compute::mir_const::hc3515bb4466ed9b3
  71:     0x7fe469b0a4cb - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_const>::compute::he95dc3e0c3f86dc7
  72:     0x7fe469c51f5a - rustc::dep_graph::graph::DepGraph::with_task_impl::h5be652c692dc409d
  73:     0x7fe469b35145 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h42eeb27492d3723a
  74:     0x7fe469e20b15 - rustc_mir::transform::qualify_consts::mir_const_qualif::hd2843ee34a3dc5d5
  75:     0x7fe469bea987 - rustc::ty::query::__query_compute::mir_const_qualif::h241800c190c483c8
  76:     0x7fe469b0a89b - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_const_qualif>::compute::h9de41e3fd16dbfff
  77:     0x7fe469c4d82d - rustc::dep_graph::graph::DepGraph::with_task_impl::h35d46e0645cb8b9b
  78:     0x7fe469b5638c - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h97f89de2e33c512c
  79:     0x7fe469af4bcf - rustc_mir::transform::mir_validated::h5bf799490b5b54c3
  80:     0x7fe469be9d47 - rustc::ty::query::__query_compute::mir_validated::h9d8f3d8fb0921797
  81:     0x7fe469b0a68b - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_validated>::compute::hda79517c6c5929cf
  82:     0x7fe469c58bcd - rustc::dep_graph::graph::DepGraph::with_task_impl::hcf137298249d0df7
  83:     0x7fe469b7dffc - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::he08db4d9d67c98c7
  84:     0x7fe469bc9f96 - rustc_mir::borrow_check::mir_borrowck::h6f4df8db09583d80
  85:     0x7fe469be99c2 - rustc::ty::query::__query_compute::mir_borrowck::hfdfaef87366e7519
  86:     0x7fe469b0a5fc - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_borrowck>::compute::h7c86a16c9036c12c
  87:     0x7fe469c59f64 - rustc::dep_graph::graph::DepGraph::with_task_impl::hd29558dcd1a1f4c9
  88:     0x7fe469b285c5 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h28abddf0758aa8f7
  89:     0x7fe469b0abb2 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::ensure_query::hc650b30d4d6b3882
  90:     0x7fe469af55c6 - rustc_mir::transform::optimized_mir::h139134c79f6f2d9e
  91:     0x7fe469be9e27 - rustc::ty::query::__query_compute::optimized_mir::h44f61d86051b7d0c
  92:     0x7fe469b0a6ab - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::optimized_mir>::compute::hbdbe95326aaa4da6
  93:     0x7fe469c4ebaa - rustc::dep_graph::graph::DepGraph::with_task_impl::h40983d3994b385f3
  94:     0x7fe469b8412b - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::he77d7da6529aaa10
  95:     0x7fe469c8b5d7 - rustc_mir::interpret::eval_context::InterpCx<M>::load_mir::h0c15a562c9f92d82
  96:     0x7fe469afb73e - rustc_mir::const_eval::const_eval_raw_provider::hca378418cb8b802f
  97:     0x7fe469bea133 - rustc::ty::query::__query_compute::const_eval_raw::h40faa9b9ed7f9ffd
  98:     0x7fe469b0a72a - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval_raw>::compute::h264c546cc8c8f7ff
  99:     0x7fe469c4b6af - rustc::dep_graph::graph::DepGraph::with_task_impl::h2a70cac1884a524e
 100:     0x7fe469b76d8d - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::hdca4664449bd6663
 101:     0x7fe469afa791 - rustc_mir::const_eval::const_eval_provider::ha3233606f24ba55a
 102:     0x7fe469757763 - rustc::ty::query::__query_compute::const_eval::hb9da53ea08710357
 103:     0x7fe4697f1f4a - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute::ha6ad154a6315d6db
 104:     0x7fe46978572a - rustc::dep_graph::graph::DepGraph::with_task_impl::h0f2fffdad4bfe656
 105:     0x7fe46983ef4a - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h9ee11c1da09150db
 106:     0x7fe4698b29d8 - <rustc_typeck::collect::CollectItemTypesVisitor as rustc::hir::intravisit::Visitor>::visit_item::h6ecf11c5154ce45d
 107:     0x7fe46975d103 - rustc::hir::map::Map::visit_item_likes_in_module::h6cf58cf1c61058c9
 108:     0x7fe4698b2424 - rustc_typeck::collect::collect_mod_item_types::ha8af4c2694cae051
 109:     0x7fe46975944a - rustc::ty::query::__query_compute::collect_mod_item_types::h0959d140ce4a445c
 110:     0x7fe4697f234b - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::collect_mod_item_types>::compute::hcc8bedd87b11d3e0
 111:     0x7fe469785e9d - rustc::dep_graph::graph::DepGraph::with_task_impl::h1149bcd7b6e6f8f9
 112:     0x7fe4698145aa - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h1ad8f3fe22fc6341
 113:     0x7fe46977d23d - rustc_typeck::check_crate::{{closure}}::{{closure}}::hef852192e4b21571
 114:     0x7fe46975d766 - rustc::util::common::time::h6c804872fd5ef88f
 115:     0x7fe46992d3fc - rustc_typeck::check_crate::h2e77f97476aecad8
 116:     0x7fe46923800a - rustc_interface::passes::analysis::h7d37d49a7360493d
 117:     0x7fe46914bc01 - rustc::ty::query::__query_compute::analysis::h1c5cc76ea5bb496b
 118:     0x7fe469134d8e - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::hcf7bc9d073dcb36b
 119:     0x7fe46915342a - rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}}::h7fc0f9f179325408
 120:     0x7fe4692b41da - rustc_interface::passes::create_global_ctxt::{{closure}}::h10595b15ffb5db35
 121:     0x7fe46915564e - rustc_interface::interface::run_compiler_in_existing_thread_pool::ha009ae4607895a11
 122:     0x7fe46918b362 - std::thread::local::LocalKey<T>::with::h30eaff0b6e71bc49
 123:     0x7fe4691903ce - scoped_tls::ScopedKey<T>::set::h6ab0051cc42102a7
 124:     0x7fe4691b11a2 - syntax::with_globals::h9994c1c3242d3263
 125:     0x7fe46911de10 - std::sys_common::backtrace::__rust_begin_short_backtrace::h229c554686840b66
 126:     0x7fe468c6325a - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:80
 127:     0x7fe469147879 - core::ops::function::FnOnce::call_once{{vtable.shim}}::hf2e117c529f2753f
 128:     0x7fe468c341ff - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h483711add4ba2330
                               at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/liballoc/boxed.rs:922
 129:     0x7fe468c61f00 - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h7605b45eb29ed0be
                               at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/liballoc/boxed.rs:922
 130:     0x7fe468c61f00 - std::sys_common::thread::start_thread::h557b0c2dc4449562
                               at src/libstd/sys_common/thread.rs:13
 131:     0x7fe468c61f00 - std::sys::unix::thread::Thread::new::thread_start::h7c2a7f9b68fe4bba
                               at src/libstd/sys/unix/thread.rs:79
 132:     0x7fe4689ce6db - start_thread
 133:     0x7fe4682eb88f - __clone
 134:                0x0 - <unknown>

error: internal compiler error: unexpected panic

[DutchGhost]

Oh, this works with other types as well, except the messages are different

enum Bug {
    V = [Vec::new; { [].len()  ].len() as isize,
}

ICE's with:

error: internal compiler error: src/librustc/ty/sty.rs:1809: sequence_element_type called on non-sequence value: [type error]

[DutchGhost]

enum Bug {
    V = [Vec::new; { [0].len()  ].len() as isize,
}

ICE's with:

error: internal compiler error: src/librustc/ty/mod.rs:2400: enum discriminant depends on generic arguments

[pnkfelix]

Its worth nothing explicitly that:

1. these ICE's are happening after we do issue a diagnostic for the parsing error
2. If you address the parsing error (presumably in the same manner that the parser is auto-correcting to make further progress), the ICE goes away

[pnkfelix]

triage: P-medium. Removing nomination.

[Centril]

Triage:

• The first example still ICEs in MIR building
• The second and third examples don't ICE anymore and need tests (without closing this issue!).

[Centril]

cc @oli-obk @varkor