ICE on unused generic in struct

[DutchGhost]

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

struct Bug<T> {
    inner: [(); { [|_: &T| {}; 0].len() }],
}

Backtrace:

   Compiling playground v0.0.1 (/playground)
error: internal compiler error: src/librustc/ty/subst.rs:557: type parameter `T/#0` (T/0) out of range when substituting (root type=Some([[closure@src/lib.rs:2:20: 2:30]; 0])) substs=[]

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:778:9
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::span_bug
  14: rustc_errors::Handler::span_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::span_bug_fmt
  21: <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty
  22: rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with
  23: <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty
  24: <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter
  25: rustc::ty::fold::TypeFoldable::fold_with
  26: rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with
  27: <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty
  28: <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter
  29: rustc::ty::fold::TypeFoldable::fold_with
  30: rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with
  31: <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty
  32: <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter
  33: rustc::ty::fold::TypeFoldable::fold_with
  34: rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with
  35: <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty
  36: rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with
  37: <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty
  38: rustc::traits::codegen::<impl rustc::ty::context::TyCtxt>::subst_and_normalize_erasing_regions
  39: rustc_mir::interpret::eval_context::InterpCx<M>::layout_of_local
  40: rustc_mir::interpret::place::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_place
  41: rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::run
  42: rustc_mir::const_eval::const_eval_raw_provider
  43: rustc::ty::query::__query_compute::const_eval_raw
  44: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval_raw>::compute
  45: rustc::dep_graph::graph::DepGraph::with_task_impl
  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::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  52: rustc_mir::const_eval::const_eval_provider
  53: rustc::ty::query::__query_compute::const_eval
  54: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute
  55: rustc::dep_graph::graph::DepGraph::with_task_impl
  56: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  57: rustc::ty::sty::Const::eval
  58: <rustc::traits::project::AssocTypeNormalizer as rustc::ty::fold::TypeFolder>::fold_ty
  59: rustc::traits::project::normalize
  60: rustc_typeck::check::FnCtxt::normalize_associated_types_in
  61: <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
  62: rustc::ty::context::GlobalCtxt::enter_local
  63: rustc_typeck::check::wfcheck::check_item_well_formed
  64: rustc::ty::query::__query_compute::check_item_well_formed
  65: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::check_item_well_formed>::compute
  66: rustc::dep_graph::graph::DepGraph::with_task_impl
  67: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  68: <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc::hir::itemlikevisit::ParItemLikeVisitor>::visit_item
  69: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:80
  70: rustc_data_structures::sync::par_for_each_in
  71: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:80
  72: rustc::hir::Crate::par_visit_all_item_likes
  73: rustc::util::common::time
  74: rustc_typeck::check_crate
  75: rustc_interface::passes::analysis
  76: rustc::ty::query::__query_compute::analysis
  77: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  78: rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}}
  79: rustc_interface::passes::create_global_ctxt::{{closure}}
  80: rustc_interface::interface::run_compiler_in_existing_thread_pool
  81: std::thread::local::LocalKey<T>::with
  82: scoped_tls::ScopedKey<T>::set
  83: syntax::with_globals
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:     0x7f5d7e137af4 - backtrace::backtrace::libunwind::trace::hda41dbcdfba36aa0
                               at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/libunwind.rs:88
   1:     0x7f5d7e137af4 - backtrace::backtrace::trace_unsynchronized::h1a8d6e1f8cb3f5d4
                               at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/mod.rs:66
   2:     0x7f5d7e137af4 - std::sys_common::backtrace::_print_fmt::h610c4127487e10da
                               at src/libstd/sys_common/backtrace.rs:76
   3:     0x7f5d7e137af4 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h0722dc552e01bd1d
                               at src/libstd/sys_common/backtrace.rs:60
   4:     0x7f5d7e17012c - core::fmt::write::h01edf6dd68a42c9c
                               at src/libcore/fmt/mod.rs:1030
   5:     0x7f5d7e12bd17 - std::io::Write::write_fmt::hf15985f193f03c04
                               at src/libstd/io/mod.rs:1412
   6:     0x7f5d7e13c325 - std::sys_common::backtrace::_print::hd8d5d08a1795e743
                               at src/libstd/sys_common/backtrace.rs:64
   7:     0x7f5d7e13c325 - std::sys_common::backtrace::print::hf89a79e3921a2366
                               at src/libstd/sys_common/backtrace.rs:49
   8:     0x7f5d7e13c325 - std::panicking::default_hook::{{closure}}::h3a8f42beb3bb8ae3
                               at src/libstd/panicking.rs:196
   9:     0x7f5d7e13c016 - std::panicking::default_hook::h8f803b0bc31a5c37
                               at src/libstd/panicking.rs:210
  10:     0x7f5d7e673483 - rustc_driver::report_ice::he98718c53edc6d3d
  11:     0x7f5d7e13cb0c - std::panicking::rust_panic_with_hook::h825f041245da8739
                               at src/libstd/panicking.rs:477
  12:     0x7f5d7e13c5c2 - std::panicking::continue_panic_fmt::hbe0378e33481e81b
                               at src/libstd/panicking.rs:380
  13:     0x7f5d7e13c4b6 - rust_begin_unwind
                               at src/libstd/panicking.rs:307
  14:     0x7f5d7e169aca - core::panicking::panic_fmt::h527855ce0bc891f6
                               at src/libcore/panicking.rs:85
  15:     0x7f5d7e169d07 - core::result::unwrap_failed::ha8b77e6004f0ba38
                               at src/libcore/result.rs:1165
  16:     0x7f5d8044efe5 - rustc_errors::Handler::force_print_diagnostic::h807dd1aae3e0d79e
  17:     0x7f5d7fd21d91 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::try_print_query_stack::h8734d6360e0a8b59
  18:     0x7f5d7e674095 - rustc_driver::report_ice::he98718c53edc6d3d
  19:     0x7f5d7e13cb0c - std::panicking::rust_panic_with_hook::h825f041245da8739
                               at src/libstd/panicking.rs:477
  20:     0x7f5d7ffbe8cd - std::panicking::begin_panic::h97acaf3e9cd227e4
  21:     0x7f5d7f92870c - rustc_errors::HandlerInner::span_bug::h5d7a04d74e00c15b
  22:     0x7f5d7f928a2a - rustc_errors::Handler::span_bug::h8fc1a2348a2faf0a
  23:     0x7f5d7fcde8ce - rustc::util::bug::opt_span_bug_fmt::{{closure}}::hf2652d3cbc7068ac
  24:     0x7f5d7fcd9933 - rustc::ty::context::tls::with_opt::{{closure}}::h0fe4f06c0a285fde
  25:     0x7f5d7fcd98a3 - rustc::ty::context::tls::with_context_opt::h01f88b941c2d3d77
  26:     0x7f5d7fcd98e7 - rustc::ty::context::tls::with_opt::hac6f601ca34cd941
  27:     0x7f5d7fcde7d8 - rustc::util::bug::opt_span_bug_fmt::h234c815c9e7b30ef
  28:     0x7f5d7fcde78a - rustc::util::bug::span_bug_fmt::h20b9ffbed9c0891c
  29:     0x7f5d7faeb0ff - <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty::h9fc1968e8e1b2aa8
  30:     0x7f5d7ff46cbc - rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with::h9c270ab536977c7f
  31:     0x7f5d7faeae7e - <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty::h9fc1968e8e1b2aa8
  32:     0x7f5d7fb11bb6 - <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter::h8400a40b9c4e6b9a
  33:     0x7f5d7ff3720b - rustc::ty::fold::TypeFoldable::fold_with::hbe621148af1523b0
  34:     0x7f5d7ff46e2b - rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with::h9c270ab536977c7f
  35:     0x7f5d7faeae7e - <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty::h9fc1968e8e1b2aa8
  36:     0x7f5d7fb11e86 - <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter::h8454765d432a4096
  37:     0x7f5d7ff373ec - rustc::ty::fold::TypeFoldable::fold_with::hc468099c6af1cfc8
  38:     0x7f5d7ff46d1e - rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with::h9c270ab536977c7f
  39:     0x7f5d7faeae7e - <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty::h9fc1968e8e1b2aa8
  40:     0x7f5d7fb11bb6 - <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter::h8400a40b9c4e6b9a
  41:     0x7f5d7ff3720b - rustc::ty::fold::TypeFoldable::fold_with::hbe621148af1523b0
  42:     0x7f5d7ff46d9b - rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with::h9c270ab536977c7f
  43:     0x7f5d7faeae7e - <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty::h9fc1968e8e1b2aa8
  44:     0x7f5d7ff46c34 - rustc::ty::structural_impls::<impl rustc::ty::fold::TypeFoldable for &rustc::ty::TyS>::super_fold_with::h9c270ab536977c7f
  45:     0x7f5d7faeae7e - <rustc::ty::subst::SubstFolder as rustc::ty::fold::TypeFolder>::fold_ty::h9fc1968e8e1b2aa8
  46:     0x7f5d7f07e17b - rustc::traits::codegen::<impl rustc::ty::context::TyCtxt>::subst_and_normalize_erasing_regions::h69ac16e2dde194e5
  47:     0x7f5d7f175794 - rustc_mir::interpret::eval_context::InterpCx<M>::layout_of_local::h7e72eb81e13c3365
  48:     0x7f5d7f17b436 - rustc_mir::interpret::place::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_place::h523e4c7a3524046c
  49:     0x7f5d7f18d64f - rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::run::hfddca9f447f81347
  50:     0x7f5d7efe5d95 - rustc_mir::const_eval::const_eval_raw_provider::hca378418cb8b802f
  51:     0x7f5d7f0d4133 - rustc::ty::query::__query_compute::const_eval_raw::h40faa9b9ed7f9ffd
  52:     0x7f5d7eff472a - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval_raw>::compute::h264c546cc8c8f7ff
  53:     0x7f5d7f1356af - rustc::dep_graph::graph::DepGraph::with_task_impl::h2a70cac1884a524e
  54:     0x7f5d7f060d8d - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::hdca4664449bd6663
  55:     0x7f5d7efe4791 - rustc_mir::const_eval::const_eval_provider::ha3233606f24ba55a
  56:     0x7f5d7f0d3523 - rustc::ty::query::__query_compute::const_eval::h0c9cbc2ee84a0954
  57:     0x7f5d7eff453a - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute::ha6ad154a6315d6db
  58:     0x7f5d7f1348ba - rustc::dep_graph::graph::DepGraph::with_task_impl::h1e8a994470cda8eb
  59:     0x7f5d7f04472b - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h9b8e8aa96625b2a7
  60:     0x7f5d7efe453a - rustc_mir::const_eval::const_eval_provider::ha3233606f24ba55a
  61:     0x7f5d7fafdd2a - rustc::ty::query::__query_compute::const_eval::hdcd5000f53247e70
  62:     0x7f5d7fef26fa - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::const_eval>::compute::ha6ad154a6315d6db
  63:     0x7f5d7fa55726 - rustc::dep_graph::graph::DepGraph::with_task_impl::h62d1fab1bc159d96
  64:     0x7f5d7fdc45b4 - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h981337fab9d39210
  65:     0x7f5d7ff4a5fe - rustc::ty::sty::Const::eval::h0414809ff02bcda4
  66:     0x7f5d7ff2d7a8 - <rustc::traits::project::AssocTypeNormalizer as rustc::ty::fold::TypeFolder>::fold_ty::h2b7457cd882278f8
  67:     0x7f5d7edd0702 - rustc::traits::project::normalize::h60f46f5d1c5639d2
  68:     0x7f5d7ebfd037 - rustc_typeck::check::FnCtxt::normalize_associated_types_in::he38c3b31e77883a8
  69:     0x7f5d7eccd83c - <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::fold::he6498e22241dcdc8
  70:     0x7f5d7ed5e36b - rustc::ty::context::GlobalCtxt::enter_local::hceda0adbe885e557
  71:     0x7f5d7ec26ce6 - rustc_typeck::check::wfcheck::check_item_well_formed::h424e7a4b21128c9a
  72:     0x7f5d7ec4336a - rustc::ty::query::__query_compute::check_item_well_formed::h6740554c6e776f0a
  73:     0x7f5d7ecdc32b - rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::check_item_well_formed>::compute::ha97091e8ad0a4a28
  74:     0x7f5d7ec6cb3d - rustc::dep_graph::graph::DepGraph::with_task_impl::h02274190e9e1d45f
  75:     0x7f5d7ece9b7a - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::h05b66a8952f105e6
  76:     0x7f5d7ec2a146 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc::hir::itemlikevisit::ParItemLikeVisitor>::visit_item::ha7ed3e8b1755f566
  77:     0x7f5d7e14d25a - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:80
  78:     0x7f5d7eca47bc - rustc_data_structures::sync::par_for_each_in::h383c73eb700cb8af
  79:     0x7f5d7e14d25a - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:80
  80:     0x7f5d7ec1e1e3 - rustc::hir::Crate::par_visit_all_item_likes::h76ea15e5dfdd9ae2
  81:     0x7f5d7ec47adb - rustc::util::common::time::hc8688ef5cd19c790
  82:     0x7f5d7ee17553 - rustc_typeck::check_crate::h2e77f97476aecad8
  83:     0x7f5d7e72200a - rustc_interface::passes::analysis::h7d37d49a7360493d
  84:     0x7f5d7e635c01 - rustc::ty::query::__query_compute::analysis::h1c5cc76ea5bb496b
  85:     0x7f5d7e61ed8e - rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query::hcf7bc9d073dcb36b
  86:     0x7f5d7e63d42a - rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}}::h7fc0f9f179325408
  87:     0x7f5d7e79e1da - rustc_interface::passes::create_global_ctxt::{{closure}}::h10595b15ffb5db35
  88:     0x7f5d7e63f64e - rustc_interface::interface::run_compiler_in_existing_thread_pool::ha009ae4607895a11
  89:     0x7f5d7e675362 - std::thread::local::LocalKey<T>::with::h30eaff0b6e71bc49
  90:     0x7f5d7e67a3ce - scoped_tls::ScopedKey<T>::set::h6ab0051cc42102a7
  91:     0x7f5d7e69b1a2 - syntax::with_globals::h9994c1c3242d3263
  92:     0x7f5d7e607e10 - std::sys_common::backtrace::__rust_begin_short_backtrace::h229c554686840b66
  93:     0x7f5d7e14d25a - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:80
  94:     0x7f5d7e631879 - core::ops::function::FnOnce::call_once{{vtable.shim}}::hf2e117c529f2753f
  95:     0x7f5d7e11e1ff - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h483711add4ba2330
                               at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/liballoc/boxed.rs:922
  96:     0x7f5d7e14bf00 - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h7605b45eb29ed0be
                               at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/liballoc/boxed.rs:922
  97:     0x7f5d7e14bf00 - std::sys_common::thread::start_thread::h557b0c2dc4449562
                               at src/libstd/sys_common/thread.rs:13
  98:     0x7f5d7e14bf00 - std::sys::unix::thread::Thread::new::thread_start::h7c2a7f9b68fe4bba
                               at src/libstd/sys/unix/thread.rs:79
  99:     0x7f5d7deb86db - start_thread
 100:     0x7f5d7d7d588f - __clone
 101:                0x0 - <unknown>

error: internal compiler error: unexpected panic

Also I noted an illigal instruction in the output of how it was compiled. It says so at the verry verry end of this output:
https://pastebin.com/Wd299cWN
or easier to see in this screenshot: http://prntscr.com/qc8252

[DutchGhost]

A quick look on godbold gives that this ICE's in 1.17, 1.18, and from 1.22 including onwards

[DutchGhost]

The illigal instruction happens when export RUST_BACKTRACE=1 is set, and cargo is runned with cargo build -v

[pnkfelix]

triage: P-high, removing nomination.

[camelid]

@rustbot modify labels: E-needs-bisection

[camelid]

I did a rough bisection with Godbolt and found this ICE was introduced in the Rust 1.17 release. Though this never worked (at least on stable); in previous versions there were various const-eval non-ICE errors.

[camelid]

Okay, I ran cargo bisect-rustc:

searched toolchains nightly-2017-02-28 through nightly-2017-05-01


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Regression in nightly-2017-03-04
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