ICE: wfchk: type parameter .. out of range when instantiating, args=`[{const error}]`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(generic_const_exprs)]

trait Ret {
    type R;
}

struct Cond<const PRED: bool, U, V>(std::marker::PhantomData<U>);

struct RobinHashTable<const MAX_LENGTH: usize, CellIdx = <Cond<{}, usize, u32> as Ret>::R> {}

impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}

original:

#![feature(generic_const_exprs)]

trait Ret {
    type R;
}

struct Cond<const PRED: bool, U, V>(std::marker::PhantomData<U>, );

struct RobinHashTable<
    const MAX_LENGTH: usize,
    CellIdx = <Cond<{  }, usize, u32> as Ret>::R,
> {}

impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}

Version information

rustc 1.81.0-nightly (13423befc 2024-06-09)
binary: rustc
commit-hash: 13423befc40fffe23ccc6dd06868142cff9428fe
commit-date: 2024-06-09
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

error[E0405]: cannot find trait `HashMapBase` in this scope
  --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:11:15
   |
11 | impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}
   |               ^^^^^^^^^^^ not found in this scope

error[E0412]: cannot find type `MAX_LENGTH` in this scope
  --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:11:55
   |
11 | impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}
   |                                                       ^^^^^^^^^^ not found in this scope
   |
help: you might be missing a type parameter
   |
11 | impl<CellIdx, MAX_LENGTH> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}
   |             ++++++++++++

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:1:12
  |
1 | #![feature(generic_const_exprs)]
  |            ^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
  = note: `#[warn(incomplete_features)]` on by default

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:11:78
   |
11 | impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}
   |                                                                              ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs`

error[E0392]: type parameter `V` is never used
 --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:7:34
  |
7 | struct Cond<const PRED: bool, U, V>(std::marker::PhantomData<U>);
  |                                  ^ unused type parameter
  |
  = help: consider removing `V`, referring to it in a field, or using a marker such as `PhantomData`
  = help: if you intended `V` to be a const parameter, use `const V: /* Type */` instead

error[E0308]: mismatched types
 --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:9:64
  |
9 | struct RobinHashTable<const MAX_LENGTH: usize, CellIdx = <Cond<{}, usize, u32> as Ret>::R> {}
  |                                                                ^^ expected `bool`, found `()`

error[E0392]: type parameter `CellIdx` is never used
 --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:9:48
  |
9 | struct RobinHashTable<const MAX_LENGTH: usize, CellIdx = <Cond<{}, usize, u32> as Ret>::R> {}
  |                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused type parameter
  |
  = help: consider removing `CellIdx`, referring to it in a field, or using a marker such as `PhantomData`
  = help: if you intended `CellIdx` to be a const parameter, use `const CellIdx: /* Type */` instead

error[E0747]: unresolved item provided when a constant was expected
  --> /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:11:55
   |
11 | impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<MAX_LENGTH, CellIdx> {}
   |                                                       ^^^^^^^^^^
   |
help: if this generic argument was intended as a const parameter, surround it with braces
   |
11 | impl<CellIdx> HashMapBase<CellIdx> for RobinHashTable<{ MAX_LENGTH }, CellIdx> {}
   |                                                       +            +

thread 'rustc' panicked at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/compiler/rustc_type_ir/src/binder.rs:721:9:
type parameter `CellIdx/#1` (CellIdx/#1/1) out of range when instantiating, args=[{const error}]
stack backtrace:
   0:     0x7a5d7b004f15 - std::backtrace_rs::backtrace::libunwind::trace::hc269bfc84eb36e15
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x7a5d7b004f15 - std::backtrace_rs::backtrace::trace_unsynchronized::hece6c4d7a612f15c
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7a5d7b004f15 - std::sys_common::backtrace::_print_fmt::h930816c48dbbaf0d
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7a5d7b004f15 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h97d89f938a66f30a
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7a5d7b055c5b - core::fmt::rt::Argument::fmt::h24d0a17c8139d598
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/core/src/fmt/rt.rs:165:63
   5:     0x7a5d7b055c5b - core::fmt::write::ha35330775473ce1b
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/core/src/fmt/mod.rs:1168:21
   6:     0x7a5d7aff9bef - std::io::Write::write_fmt::h43aadac447ba03dc
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/io/mod.rs:1835:15
   7:     0x7a5d7b004cee - std::sys_common::backtrace::_print::h26d59bbced8ffda1
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7a5d7b004cee - std::sys_common::backtrace::print::ha970e07731260ee4
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7a5d7b007729 - std::panicking::default_hook::{{closure}}::hf9289ff1d818f2e0
  10:     0x7a5d7b0074ca - std::panicking::default_hook::h63336b0533014868
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/panicking.rs:298:9
  11:     0x7a5d777d7890 - std[6fb11aa7feb46831]::panicking::update_hook::<alloc[34e4e5571b6f83d9]::boxed::Box<rustc_driver_impl[ffae40d8b8d5c74b]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7a5d7b007e5b - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hf78a7244bd2d88ce
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/alloc/src/boxed.rs:2077:9
  13:     0x7a5d7b007e5b - std::panicking::rust_panic_with_hook::h0b57c3ef0581f5fb
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/panicking.rs:799:13
  14:     0x7a5d7b007bd4 - std::panicking::begin_panic_handler::{{closure}}::h3bf6c54ce49c26c2
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/panicking.rs:664:13
  15:     0x7a5d7b0053d9 - std::sys_common::backtrace::__rust_end_short_backtrace::h7ebf041d380b46ed
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7a5d7b007907 - rust_begin_unwind
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/panicking.rs:652:5
  17:     0x7a5d7b0521f3 - core::panicking::panic_fmt::hea580bf65fedee8d
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/core/src/panicking.rs:72:14
  18:     0x7a5d778da789 - <rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::type_param_out_of_range
  19:     0x7a5d792ee2ea - <rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt> as rustc_type_ir[f61c5ba52dab4f78]::fold::TypeFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::fold_ty
  20:     0x7a5d792ed0a6 - <&rustc_middle[d7453cc9d163243f]::ty::list::RawList<(), rustc_middle[d7453cc9d163243f]::ty::generic_args::GenericArg> as rustc_type_ir[f61c5ba52dab4f78]::fold::TypeFoldable<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::try_fold_with::<rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>
  21:     0x7a5d79e249ae - <rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt> as rustc_type_ir[f61c5ba52dab4f78]::fold::TypeFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::fold_const.warm
  22:     0x7a5d792ee267 - <rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt> as rustc_type_ir[f61c5ba52dab4f78]::fold::TypeFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::fold_ty
  23:     0x7a5d792ed015 - <&rustc_middle[d7453cc9d163243f]::ty::list::RawList<(), rustc_middle[d7453cc9d163243f]::ty::generic_args::GenericArg> as rustc_type_ir[f61c5ba52dab4f78]::fold::TypeFoldable<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::try_fold_with::<rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>
  24:     0x7a5d792ed6ac - <rustc_type_ir[f61c5ba52dab4f78]::binder::ArgFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt> as rustc_type_ir[f61c5ba52dab4f78]::fold::TypeFolder<rustc_middle[d7453cc9d163243f]::ty::context::TyCtxt>>::fold_ty
  25:     0x7a5d78f0c939 - <<dyn rustc_hir_analysis[1c7651ca8b7a2f4f]::hir_ty_lowering::HirTyLowerer>::lower_generic_args_of_path::{closure#0}::GenericArgsCtxt as rustc_hir_analysis[1c7651ca8b7a2f4f]::hir_ty_lowering::GenericArgsLowerer>::inferred_kind
  26:     0x7a5d767cdd2a - <dyn rustc_hir_analysis[1c7651ca8b7a2f4f]::hir_ty_lowering::HirTyLowerer>::lower_path
  27:     0x7a5d79199197 - <dyn rustc_hir_analysis[1c7651ca8b7a2f4f]::hir_ty_lowering::HirTyLowerer>::lower_ty_common::{closure#0}
  28:     0x7a5d7674409b - rustc_hir_analysis[1c7651ca8b7a2f4f]::collect::type_of::type_of
  29:     0x7a5d78dd0c2a - rustc_query_impl[1410ec32161e1f70]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1410ec32161e1f70]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 8usize]>>
  30:     0x7a5d78dcf81b - rustc_query_system[71bc59e02034b9b1]::query::plumbing::try_execute_query::<rustc_query_impl[1410ec32161e1f70]::DynamicConfig<rustc_query_system[71bc59e02034b9b1]::query::caches::DefIdCache<rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[1410ec32161e1f70]::plumbing::QueryCtxt, false>
  31:     0x7a5d78dcf3bb - rustc_query_impl[1410ec32161e1f70]::query_impl::type_of::get_query_non_incr::__rust_end_short_backtrace
  32:     0x7a5d78f9efcf - <rustc_hir_analysis[1c7651ca8b7a2f4f]::collect::CollectItemTypesVisitor as rustc_hir[b11a8aea6cdb8d1a]::intravisit::Visitor>::visit_item
  33:     0x7a5d7675f6c0 - rustc_hir_analysis[1c7651ca8b7a2f4f]::check::wfcheck::check_well_formed
  34:     0x7a5d791c52a9 - rustc_query_impl[1410ec32161e1f70]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1410ec32161e1f70]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 1usize]>>
  35:     0x7a5d791c5526 - rustc_query_system[71bc59e02034b9b1]::query::plumbing::try_execute_query::<rustc_query_impl[1410ec32161e1f70]::DynamicConfig<rustc_query_system[71bc59e02034b9b1]::query::caches::VecCache<rustc_hir[b11a8aea6cdb8d1a]::hir_id::OwnerId, rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[1410ec32161e1f70]::plumbing::QueryCtxt, false>
  36:     0x7a5d791c5286 - rustc_query_impl[1410ec32161e1f70]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  37:     0x7a5d791c6009 - rustc_hir_analysis[1c7651ca8b7a2f4f]::check::wfcheck::check_mod_type_wf
  38:     0x7a5d791c5e4f - rustc_query_impl[1410ec32161e1f70]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1410ec32161e1f70]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 1usize]>>
  39:     0x7a5d7972c1fa - rustc_query_system[71bc59e02034b9b1]::query::plumbing::try_execute_query::<rustc_query_impl[1410ec32161e1f70]::DynamicConfig<rustc_query_system[71bc59e02034b9b1]::query::caches::DefaultCache<rustc_span[3fc851bceb4adf61]::def_id::LocalModDefId, rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[1410ec32161e1f70]::plumbing::QueryCtxt, false>
  40:     0x7a5d7972bfb5 - rustc_query_impl[1410ec32161e1f70]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  41:     0x7a5d78ff37ea - rustc_hir_analysis[1c7651ca8b7a2f4f]::check_crate
  42:     0x7a5d791ba8be - rustc_interface[f4a2ea540be086e6]::passes::analysis
  43:     0x7a5d791ba41b - rustc_query_impl[1410ec32161e1f70]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1410ec32161e1f70]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 1usize]>>
  44:     0x7a5d799cdda5 - rustc_query_system[71bc59e02034b9b1]::query::plumbing::try_execute_query::<rustc_query_impl[1410ec32161e1f70]::DynamicConfig<rustc_query_system[71bc59e02034b9b1]::query::caches::SingleCache<rustc_middle[d7453cc9d163243f]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[1410ec32161e1f70]::plumbing::QueryCtxt, false>
  45:     0x7a5d799cdb0f - rustc_query_impl[1410ec32161e1f70]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  46:     0x7a5d7984f692 - rustc_interface[f4a2ea540be086e6]::interface::run_compiler::<core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>, rustc_driver_impl[ffae40d8b8d5c74b]::run_compiler::{closure#0}>::{closure#1}
  47:     0x7a5d79804f67 - std[6fb11aa7feb46831]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[f4a2ea540be086e6]::util::run_in_thread_with_globals<rustc_interface[f4a2ea540be086e6]::util::run_in_thread_pool_with_globals<rustc_interface[f4a2ea540be086e6]::interface::run_compiler<core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>, rustc_driver_impl[ffae40d8b8d5c74b]::run_compiler::{closure#0}>::{closure#1}, core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>>::{closure#0}, core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>>
  48:     0x7a5d79804d2a - <<std[6fb11aa7feb46831]::thread::Builder>::spawn_unchecked_<rustc_interface[f4a2ea540be086e6]::util::run_in_thread_with_globals<rustc_interface[f4a2ea540be086e6]::util::run_in_thread_pool_with_globals<rustc_interface[f4a2ea540be086e6]::interface::run_compiler<core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>, rustc_driver_impl[ffae40d8b8d5c74b]::run_compiler::{closure#0}>::{closure#1}, core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>>::{closure#0}, core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[b05d301dbc549eb0]::result::Result<(), rustc_span[3fc851bceb4adf61]::ErrorGuaranteed>>::{closure#2} as core[b05d301dbc549eb0]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  49:     0x7a5d7b011e4b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he97bec9b57692eb6
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/alloc/src/boxed.rs:2063:9
  50:     0x7a5d7b011e4b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h5ef09d5fe1e7a265
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/alloc/src/boxed.rs:2063:9
  51:     0x7a5d7b011e4b - std::sys::pal::unix::thread::Thread::new::thread_start::h71e84f01f2e92ad3
                               at /rustc/13423befc40fffe23ccc6dd06868142cff9428fe/library/std/src/sys/pal/unix/thread.rs:108:17
  52:     0x7a5d744a6ded - <unknown>
  53:     0x7a5d7452a0dc - <unknown>
  54:                0x0 - <unknown>

error: 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: please make sure that you have updated to the latest nightly

note: rustc 1.81.0-nightly (13423befc 2024-06-09) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [type_of] computing type of `<impl at /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:11:1: 11:75>`
#1 [check_well_formed] checking that `<impl at /tmp/icemaker_global_tempdir.7MOg4WzJ7ybU/rustc_testrunner_tmpdir_reporting.HyzgwWnQ2tfu/mvce.rs:11:1: 11:75>` is well-formed
end of query stack
error: aborting due to 7 previous errors; 1 warning emitted

Some errors have detailed explanations: E0308, E0392, E0405, E0412, E0601, E0747.
For more information about an error, try `rustc --explain E0308`.

@rustbot label +F-generic_const_exprs

[theemathas]

Minimized:

#![feature(generic_const_exprs)]
#![allow(incomplete_features)]

struct Cond<const B: bool>;

struct Thing<T = Cond<0>>(T);

impl Thing {}

Compiler output

   Compiling playground v0.0.1 (/playground)
error[E0308]: mismatched types
 --> src/lib.rs:6:23
  |
6 | struct Thing<T = Cond<0>>(T);
  |                       ^ expected `bool`, found integer

thread 'rustc' panicked at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/compiler/rustc_type_ir/src/binder.rs:721:9:
type parameter `T/#0` (T/#0/0) out of range when instantiating, args=[]
stack backtrace:
   0:     0x7fafbbd3ff15 - std::backtrace_rs::backtrace::libunwind::trace::hfca91910e8bd6208
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x7fafbbd3ff15 - std::backtrace_rs::backtrace::trace_unsynchronized::h5a4f6fc8cd78f634
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fafbbd3ff15 - std::sys_common::backtrace::_print_fmt::h5d0b0e53bade0c48
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7fafbbd3ff15 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h19ae2d3e45efa1aa
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fafbbd90c5b - core::fmt::rt::Argument::fmt::h56833048848af921
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/core/src/fmt/rt.rs:165:63
   5:     0x7fafbbd90c5b - core::fmt::write::h73ea2fd46689cbd2
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/core/src/fmt/mod.rs:1168:21
   6:     0x7fafbbd34bef - std::io::Write::write_fmt::h57421db57be4d88a
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/io/mod.rs:1835:15
   7:     0x7fafbbd3fcee - std::sys_common::backtrace::_print::h49b789ad9bc424ff
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7fafbbd3fcee - std::sys_common::backtrace::print::h30b346ab119f042f
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7fafbbd42729 - std::panicking::default_hook::{{closure}}::hac3e4c7a36a1e544
  10:     0x7fafbbd424ca - std::panicking::default_hook::h36c5bd5715913de7
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/panicking.rs:298:9
  11:     0x7fafbef8d100 - std[a54bcd08e7411830]::panicking::update_hook::<alloc[bc734d13426437c7]::boxed::Box<rustc_driver_impl[814eaf686e5216f9]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7fafbbd42e5b - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hb1741174b795cf35
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/alloc/src/boxed.rs:2077:9
  13:     0x7fafbbd42e5b - std::panicking::rust_panic_with_hook::hf07571b7e9d43806
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/panicking.rs:799:13
  14:     0x7fafbbd42bd4 - std::panicking::begin_panic_handler::{{closure}}::hdc742db4bd338eb8
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/panicking.rs:664:13
  15:     0x7fafbbd403d9 - std::sys_common::backtrace::__rust_end_short_backtrace::h2d0cc130f1c87c64
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7fafbbd42907 - rust_begin_unwind
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/panicking.rs:652:5
  17:     0x7fafbbd8d1f3 - core::panicking::panic_fmt::hc9533aa472778eef
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/core/src/panicking.rs:72:14
  18:     0x7fafbf08fff9 - <rustc_type_ir[92f743e515eeefed]::binder::ArgFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt>>::type_param_out_of_range
  19:     0x7fafc0a73c6a - <rustc_type_ir[92f743e515eeefed]::binder::ArgFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt> as rustc_type_ir[92f743e515eeefed]::fold::TypeFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt>>::fold_ty
  20:     0x7fafc0a72995 - <&rustc_middle[b41b0863c4e23e8a]::ty::list::RawList<(), rustc_middle[b41b0863c4e23e8a]::ty::generic_args::GenericArg> as rustc_type_ir[92f743e515eeefed]::fold::TypeFoldable<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt>>::try_fold_with::<rustc_type_ir[92f743e515eeefed]::binder::ArgFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt>>
  21:     0x7fafc15d6f02 - <rustc_type_ir[92f743e515eeefed]::binder::ArgFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt> as rustc_type_ir[92f743e515eeefed]::fold::TypeFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt>>::fold_const.warm
  22:     0x7fafc0a7322f - <rustc_type_ir[92f743e515eeefed]::binder::ArgFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt> as rustc_type_ir[92f743e515eeefed]::fold::TypeFolder<rustc_middle[b41b0863c4e23e8a]::ty::context::TyCtxt>>::fold_ty
  23:     0x7fafc06acf79 - <<dyn rustc_hir_analysis[6b7f69c937aac3d5]::hir_ty_lowering::HirTyLowerer>::lower_generic_args_of_path::{closure#0}::GenericArgsCtxt as rustc_hir_analysis[6b7f69c937aac3d5]::hir_ty_lowering::GenericArgsLowerer>::inferred_kind
  24:     0x7fafbdfc2d2a - <dyn rustc_hir_analysis[6b7f69c937aac3d5]::hir_ty_lowering::HirTyLowerer>::lower_path
  25:     0x7fafc099de17 - <dyn rustc_hir_analysis[6b7f69c937aac3d5]::hir_ty_lowering::HirTyLowerer>::lower_ty_common::{closure#0}
  26:     0x7fafbddc165b - rustc_hir_analysis[6b7f69c937aac3d5]::collect::type_of::type_of
  27:     0x7fafc059c82a - rustc_query_impl[b746354c2bcfb267]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b746354c2bcfb267]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 8usize]>>
  28:     0x7fafc059b427 - rustc_query_system[6e6ff034b5afc6]::query::plumbing::try_execute_query::<rustc_query_impl[b746354c2bcfb267]::DynamicConfig<rustc_query_system[6e6ff034b5afc6]::query::caches::DefIdCache<rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[b746354c2bcfb267]::plumbing::QueryCtxt, false>
  29:     0x7fafc059afe7 - rustc_query_impl[b746354c2bcfb267]::query_impl::type_of::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7fafc073eb8f - <rustc_hir_analysis[6b7f69c937aac3d5]::collect::CollectItemTypesVisitor as rustc_hir[e257be9344e55af2]::intravisit::Visitor>::visit_item
  31:     0x7fafbdddccc0 - rustc_hir_analysis[6b7f69c937aac3d5]::check::wfcheck::check_well_formed
  32:     0x7fafc092c1e9 - rustc_query_impl[b746354c2bcfb267]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b746354c2bcfb267]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 1usize]>>
  33:     0x7fafc092c466 - rustc_query_system[6e6ff034b5afc6]::query::plumbing::try_execute_query::<rustc_query_impl[b746354c2bcfb267]::DynamicConfig<rustc_query_system[6e6ff034b5afc6]::query::caches::VecCache<rustc_hir[e257be9344e55af2]::hir_id::OwnerId, rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[b746354c2bcfb267]::plumbing::QueryCtxt, false>
  34:     0x7fafc092c1c6 - rustc_query_impl[b746354c2bcfb267]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  35:     0x7fafc092cf37 - rustc_hir_analysis[6b7f69c937aac3d5]::check::wfcheck::check_mod_type_wf
  36:     0x7fafc092cd7b - rustc_query_impl[b746354c2bcfb267]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b746354c2bcfb267]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 1usize]>>
  37:     0x7fafc0edc6fa - rustc_query_system[6e6ff034b5afc6]::query::plumbing::try_execute_query::<rustc_query_impl[b746354c2bcfb267]::DynamicConfig<rustc_query_system[6e6ff034b5afc6]::query::caches::DefaultCache<rustc_span[8dc60f5d6165f5e6]::def_id::LocalModDefId, rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[b746354c2bcfb267]::plumbing::QueryCtxt, false>
  38:     0x7fafc0edc4b5 - rustc_query_impl[b746354c2bcfb267]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  39:     0x7fafc07966ea - rustc_hir_analysis[6b7f69c937aac3d5]::check_crate
  40:     0x7fafc09217fe - rustc_interface[b431ae828ca0cbb1]::passes::analysis
  41:     0x7fafc092135b - rustc_query_impl[b746354c2bcfb267]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b746354c2bcfb267]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 1usize]>>
  42:     0x7fafc11fad65 - rustc_query_system[6e6ff034b5afc6]::query::plumbing::try_execute_query::<rustc_query_impl[b746354c2bcfb267]::DynamicConfig<rustc_query_system[6e6ff034b5afc6]::query::caches::SingleCache<rustc_middle[b41b0863c4e23e8a]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[b746354c2bcfb267]::plumbing::QueryCtxt, false>
  43:     0x7fafc11faacf - rustc_query_impl[b746354c2bcfb267]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  44:     0x7fafc1007512 - rustc_interface[b431ae828ca0cbb1]::interface::run_compiler::<core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>, rustc_driver_impl[814eaf686e5216f9]::run_compiler::{closure#0}>::{closure#1}
  45:     0x7fafc0fcda67 - std[a54bcd08e7411830]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[b431ae828ca0cbb1]::util::run_in_thread_with_globals<rustc_interface[b431ae828ca0cbb1]::util::run_in_thread_pool_with_globals<rustc_interface[b431ae828ca0cbb1]::interface::run_compiler<core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>, rustc_driver_impl[814eaf686e5216f9]::run_compiler::{closure#0}>::{closure#1}, core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>>::{closure#0}, core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>>
  46:     0x7fafc0fcd82a - <<std[a54bcd08e7411830]::thread::Builder>::spawn_unchecked_<rustc_interface[b431ae828ca0cbb1]::util::run_in_thread_with_globals<rustc_interface[b431ae828ca0cbb1]::util::run_in_thread_pool_with_globals<rustc_interface[b431ae828ca0cbb1]::interface::run_compiler<core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>, rustc_driver_impl[814eaf686e5216f9]::run_compiler::{closure#0}>::{closure#1}, core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>>::{closure#0}, core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[bdee16f735ec8991]::result::Result<(), rustc_span[8dc60f5d6165f5e6]::ErrorGuaranteed>>::{closure#2} as core[bdee16f735ec8991]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  47:     0x7fafbbd4ce4b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3c82973632029444
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/alloc/src/boxed.rs:2063:9
  48:     0x7fafbbd4ce4b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he2c2231a15a5a037
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/alloc/src/boxed.rs:2063:9
  49:     0x7fafbbd4ce4b - std::sys::pal::unix::thread::Thread::new::thread_start::haa4b727517fcd5d2
                               at /rustc/f21554f7f0ff447b803961c51acafde04553c1ed/library/std/src/sys/pal/unix/thread.rs:108:17
  50:     0x7fafbbc5a609 - start_thread
  51:     0x7fafbbb7d353 - clone
  52:                0x0 - <unknown>

error: 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: please make sure that you have updated to the latest nightly

note: please attach the file at `/playground/rustc-ice-2024-06-09T15_00_43-78.txt` to your bug report

note: compiler flags: --crate-type lib -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [type_of] computing type of `<impl at src/lib.rs:8:1: 8:11>`
#1 [check_well_formed] checking that `<impl at src/lib.rs:8:1: 8:11>` is well-formed
end of query stack
For more information about this error, try `rustc --explain E0308`.
error: could not compile `playground` (lib) due to 1 previous error

[GrigorenkoPV]

Minimized:

#![feature(generic_const_exprs)]
#![allow(incomplete_features)]

struct Cond<const B: bool>;

struct Thing<T = Cond<0>>(T);

impl Thing {}

Compiler output

This first regresses from correctly giving an error to ICEing in nightly-2021-09-01 (5d68044...29ef6cf)

error: internal compiler error: compiler/rustc_middle/src/ty/subst.rs:534:17: type parameter `T/#0` (T/0) out of range when substituting, substs=[]
 --> src/lib.rs:9:6
  |
9 | impl Thing {}
  |      ^^^^^

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/29ef6cf1637aa8317f8911f93f14e18d404c1b0e/compiler/rustc_errors/src/lib.rs:1093:9
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 1.56.0-nightly (29ef6cf16 2021-08-31) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental -C target-cpu=native -C link-arg=-fuse-ld=mold --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [type_of] computing type of `<impl at src/lib.rs:9:1: 9:14>`
#1 [collect_mod_item_types] collecting item types in top-level module
end of query stack

[matthiaskrgr]

where's the const error though? 😅