ICE: `field.0.is_sized()`

[matthiaskrgr]

Code

use std::sync::OnceLock;

pub struct WeakOnce<T>(OnceLock<dyn Iterator<Item: '_>>);

pub(crate) static ONCE: WeakOnce<Context> = WeakOnce::new();

Meta

rustc --version --verbose:

rustc 1.73.0-nightly (4c8bb79d9 2023-07-15)
binary: rustc
commit-hash: 4c8bb79d9f565115637cc6da739f8389e79f3a29
commit-date: 2023-07-15
host: x86_64-unknown-linux-gnu
release: 1.73.0-nightly
LLVM version: 16.0.5

Error output

error[E0106]: missing lifetime specifier
 --> treereduce.out:3:52
  |
3 | pub struct WeakOnce<T>(OnceLock<dyn Iterator<Item: '_>>);
  |                                                    ^^ expected named lifetime parameter
  |
  = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
help: consider making the bound lifetime-generic with a new `'a` lifetime
  |
3 | pub struct WeakOnce<T>(OnceLock<dyn for<'a> Iterator<Item: 'a>>);
  |                                     +++++++                ~~
help: consider introducing a named lifetime parameter
  |
3 | pub struct WeakOnce<'a, T>(OnceLock<dyn Iterator<Item: 'a>>);
  |                     +++                                ~~

error[E0412]: cannot find type `Context` in this scope
 --> treereduce.out:5:34
  |
5 | pub(crate) static ONCE: WeakOnce<Context> = WeakOnce::new();
  |                                  ^^^^^^^ not found in this scope
  |
help: consider importing this struct
  |
1 + use std::task::Context;
  |

error[E0658]: associated type bounds are unstable
 --> treereduce.out:3:46
  |
3 | pub struct WeakOnce<T>(OnceLock<dyn Iterator<Item: '_>>);
  |                                              ^^^^^^^^
  |
  = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
  = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable

error: associated type bounds are only allowed in where clauses and function signatures, not in field types
 --> treereduce.out:3:46
  |
3 | pub struct WeakOnce<T>(OnceLock<dyn Iterator<Item: '_>>);
  |                                              ^^^^^^^^

error[E0601]: `main` function not found in crate `treereduce`
 --> treereduce.out:5:61
  |
5 | pub(crate) static ONCE: WeakOnce<Context> = WeakOnce::new();
  |                                                             ^ consider adding a `main` function to `treereduce.out`

error[E0599]: no function or associated item named `new` found for struct `WeakOnce` in the current scope
 --> treereduce.out:5:55
  |
3 | pub struct WeakOnce<T>(OnceLock<dyn Iterator<Item: '_>>);
  | ---------------------- function or associated item `new` not found for this struct
4 |
5 | pub(crate) static ONCE: WeakOnce<Context> = WeakOnce::new();
  |                                                       ^^^ function or associated item not found in `WeakOnce<_>`

Backtrace

thread 'rustc' panicked at 'assertion failed: field.0.is_sized()', /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/compiler/rustc_abi/src/layout.rs:766:13
stack backtrace:
   0:     0x7f048a1641e1 - std::backtrace_rs::backtrace::libunwind::trace::h3b5c50f24cf4b35a
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f048a1641e1 - std::backtrace_rs::backtrace::trace_unsynchronized::he026a26ead582316
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f048a1641e1 - std::sys_common::backtrace::_print_fmt::h76fd67678968a4e3
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f048a1641e1 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hdd83524e3f3c2be2
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f048a1ca19c - core::fmt::rt::Argument::fmt::h654276e7f109452e
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/core/src/fmt/rt.rs:138:9
   5:     0x7f048a1ca19c - core::fmt::write::h138407e966f7b43b
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/core/src/fmt/mod.rs:1094:21
   6:     0x7f048a156b8e - std::io::Write::write_fmt::h2424dcece48dafda
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/io/mod.rs:1714:15
   7:     0x7f048a163ff5 - std::sys_common::backtrace::_print::hed0bf89a99fb894c
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f048a163ff5 - std::sys_common::backtrace::print::h247f5c941c9353a5
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f048a166da3 - std::panicking::default_hook::{{closure}}::hcccd6b964b717049
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/panicking.rs:269:22
  10:     0x7f048a166b34 - std::panicking::default_hook::hce795b61120bca6d
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/panicking.rs:288:9
  11:     0x7f048d3f827b - <rustc_driver_impl[36a7eaa3807b03c1]::install_ice_hook::{closure#0} as core[81c8fe8a09de0f06]::ops::function::FnOnce<(&core[81c8fe8a09de0f06]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  12:     0x7f048a1675ce - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h3187784b6c983a99
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/alloc/src/boxed.rs:2021:9
  13:     0x7f048a1675ce - std::panicking::rust_panic_with_hook::h46c9d18986d08847
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/panicking.rs:709:13
  14:     0x7f048a167311 - std::panicking::begin_panic_handler::{{closure}}::h9240e694e6b0cb3e
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/panicking.rs:595:13
  15:     0x7f048a164646 - std::sys_common::backtrace::__rust_end_short_backtrace::h37d9a711c5606b4e
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/sys_common/backtrace.rs:151:18
  16:     0x7f048a1670a2 - rust_begin_unwind
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/panicking.rs:593:5
  17:     0x7f048a1c6543 - core::panicking::panic_fmt::hb353582dad440800
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/core/src/panicking.rs:67:14
  18:     0x7f048a1c65d3 - core::panicking::panic::hfb3ea9ceb774db6b
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/core/src/panicking.rs:117:5
  19:     0x7f048c333230 - <rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutCx<rustc_middle[bafd45fe52eb4faf]::ty::context::TyCtxt> as rustc_abi[8d56ae912b876514]::layout::LayoutCalculator>::layout_of_union
  20:     0x7f048c31b39b - rustc_ty_utils[3b78d04571512db1]::layout::layout_of
  21:     0x7f048b437f3e - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>
  22:     0x7f048bdaa4b1 - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  23:     0x7f048bdaa102 - rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7f048b54e615 - <core[81c8fe8a09de0f06]::iter::adapters::GenericShunt<core[81c8fe8a09de0f06]::iter::adapters::by_ref_sized::ByRefSized<core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::FieldDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}::{closure#0}>>, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::convert::Infallible, &rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutError>> as core[81c8fe8a09de0f06]::iter::traits::iterator::Iterator>::next
  25:     0x7f048c320329 - core[81c8fe8a09de0f06]::iter::adapters::try_process::<core[81c8fe8a09de0f06]::iter::adapters::by_ref_sized::ByRefSized<core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::VariantDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}>>, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::convert::Infallible, &rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutError>, <core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::VariantDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}> as core[81c8fe8a09de0f06]::iter::traits::iterator::Iterator>::try_collect<rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::VariantIdx, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>>>::{closure#0}, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::VariantIdx, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>>>
  26:     0x7f048c31a0cc - rustc_ty_utils[3b78d04571512db1]::layout::layout_of
  27:     0x7f048b437f3e - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>
  28:     0x7f048bdaa4b1 - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  29:     0x7f048bdaa102 - rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7f048b54e615 - <core[81c8fe8a09de0f06]::iter::adapters::GenericShunt<core[81c8fe8a09de0f06]::iter::adapters::by_ref_sized::ByRefSized<core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::FieldDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}::{closure#0}>>, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::convert::Infallible, &rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutError>> as core[81c8fe8a09de0f06]::iter::traits::iterator::Iterator>::next
  31:     0x7f048c32039b - core[81c8fe8a09de0f06]::iter::adapters::try_process::<core[81c8fe8a09de0f06]::iter::adapters::by_ref_sized::ByRefSized<core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::VariantDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}>>, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::convert::Infallible, &rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutError>, <core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::VariantDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}> as core[81c8fe8a09de0f06]::iter::traits::iterator::Iterator>::try_collect<rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::VariantIdx, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>>>::{closure#0}, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::VariantIdx, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>>>
  32:     0x7f048c31a0cc - rustc_ty_utils[3b78d04571512db1]::layout::layout_of
  33:     0x7f048b437f3e - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>
  34:     0x7f048bdaa4b1 - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  35:     0x7f048bdaa102 - rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7f048c32096e - rustc_middle[bafd45fe52eb4faf]::query::plumbing::query_get_at::<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>>
  37:     0x7f048c31af15 - rustc_ty_utils[3b78d04571512db1]::layout::layout_of
  38:     0x7f048b437f3e - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>
  39:     0x7f048bdaa4b1 - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  40:     0x7f048bdaa102 - rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  41:     0x7f048b54e615 - <core[81c8fe8a09de0f06]::iter::adapters::GenericShunt<core[81c8fe8a09de0f06]::iter::adapters::by_ref_sized::ByRefSized<core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::FieldDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}::{closure#0}>>, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::convert::Infallible, &rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutError>> as core[81c8fe8a09de0f06]::iter::traits::iterator::Iterator>::next
  42:     0x7f048c320329 - core[81c8fe8a09de0f06]::iter::adapters::try_process::<core[81c8fe8a09de0f06]::iter::adapters::by_ref_sized::ByRefSized<core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::VariantDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}>>, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::convert::Infallible, &rustc_middle[bafd45fe52eb4faf]::ty::layout::LayoutError>, <core[81c8fe8a09de0f06]::iter::adapters::map::Map<core[81c8fe8a09de0f06]::slice::iter::Iter<rustc_middle[bafd45fe52eb4faf]::ty::VariantDef>, rustc_ty_utils[3b78d04571512db1]::layout::layout_of_uncached::{closure#8}> as core[81c8fe8a09de0f06]::iter::traits::iterator::Iterator>::try_collect<rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::VariantIdx, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>>>::{closure#0}, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::VariantIdx, rustc_index[662aeb3083791134]::vec::IndexVec<rustc_abi[8d56ae912b876514]::FieldIdx, rustc_abi[8d56ae912b876514]::Layout>>>
  43:     0x7f048c31a0cc - rustc_ty_utils[3b78d04571512db1]::layout::layout_of
  44:     0x7f048b437f3e - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>
  45:     0x7f048bdaa4b1 - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  46:     0x7f048bdaa102 - rustc_query_impl[f1760b35ee71e15a]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  47:     0x7f048c3bf883 - rustc_middle[bafd45fe52eb4faf]::query::plumbing::query_get_at::<rustc_query_system[a39b5eca44b3ed3c]::query::caches::DefaultCache<rustc_middle[bafd45fe52eb4faf]::ty::ParamEnvAnd<rustc_middle[bafd45fe52eb4faf]::ty::Ty>, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 16usize]>>>
  48:     0x7f048c3bee43 - rustc_hir_analysis[51ced00d18f9db10]::check::check::check_static_inhabited
  49:     0x7f048c3a9856 - rustc_hir_analysis[51ced00d18f9db10]::check::check::check_mod_item_types
  50:     0x7f048c15db6c - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::check_mod_item_types::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 0usize]>>
  51:     0x7f048c15db4e - <rustc_query_impl[f1760b35ee71e15a]::query_impl::check_mod_item_types::dynamic_query::{closure#2} as core[81c8fe8a09de0f06]::ops::function::FnOnce<(rustc_middle[bafd45fe52eb4faf]::ty::context::TyCtxt, rustc_span[d4de8c39017ea598]::def_id::LocalDefId)>>::call_once
  52:     0x7f048bd52b2f - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::VecCache<rustc_span[d4de8c39017ea598]::def_id::LocalDefId, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  53:     0x7f048cd2da22 - rustc_query_impl[f1760b35ee71e15a]::query_impl::check_mod_item_types::get_query_non_incr::__rust_end_short_backtrace
  54:     0x7f048c8af077 - <rustc_middle[bafd45fe52eb4faf]::hir::map::Map>::for_each_module::<rustc_hir_analysis[51ced00d18f9db10]::check_crate::{closure#6}::{closure#0}>
  55:     0x7f048c8ae2ed - <rustc_session[b1a5d361b73cfad9]::session::Session>::time::<(), rustc_hir_analysis[51ced00d18f9db10]::check_crate::{closure#6}>
  56:     0x7f048c8acf1a - rustc_hir_analysis[51ced00d18f9db10]::check_crate
  57:     0x7f048c8a433a - rustc_interface[b60702df0ae80ef4]::passes::analysis
  58:     0x7f048c87fb3a - rustc_query_impl[f1760b35ee71e15a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f1760b35ee71e15a]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 1usize]>>
  59:     0x7f048c87fb29 - <rustc_query_impl[f1760b35ee71e15a]::query_impl::analysis::dynamic_query::{closure#2} as core[81c8fe8a09de0f06]::ops::function::FnOnce<(rustc_middle[bafd45fe52eb4faf]::ty::context::TyCtxt, ())>>::call_once
  60:     0x7f048ca5bc68 - rustc_query_system[a39b5eca44b3ed3c]::query::plumbing::try_execute_query::<rustc_query_impl[f1760b35ee71e15a]::DynamicConfig<rustc_query_system[a39b5eca44b3ed3c]::query::caches::SingleCache<rustc_middle[bafd45fe52eb4faf]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[f1760b35ee71e15a]::plumbing::QueryCtxt, false>
  61:     0x7f048ca5ba47 - rustc_query_impl[f1760b35ee71e15a]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  62:     0x7f048c66e835 - <rustc_middle[bafd45fe52eb4faf]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[36a7eaa3807b03c1]::run_compiler::{closure#1}::{closure#2}::{closure#4}, core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>
  63:     0x7f048c66de62 - <rustc_interface[b60702df0ae80ef4]::interface::Compiler>::enter::<rustc_driver_impl[36a7eaa3807b03c1]::run_compiler::{closure#1}::{closure#2}, core[81c8fe8a09de0f06]::result::Result<core[81c8fe8a09de0f06]::option::Option<rustc_interface[b60702df0ae80ef4]::queries::Linker>, rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>
  64:     0x7f048c6671d5 - rustc_span[d4de8c39017ea598]::set_source_map::<core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>, rustc_interface[b60702df0ae80ef4]::interface::run_compiler<core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>, rustc_driver_impl[36a7eaa3807b03c1]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  65:     0x7f048c666c46 - <scoped_tls[121ecede58d5c05f]::ScopedKey<rustc_span[d4de8c39017ea598]::SessionGlobals>>::set::<rustc_interface[b60702df0ae80ef4]::interface::run_compiler<core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>, rustc_driver_impl[36a7eaa3807b03c1]::run_compiler::{closure#1}>::{closure#0}, core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>
  66:     0x7f048c66620c - std[fa39155a576d62c5]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[b60702df0ae80ef4]::util::run_in_thread_pool_with_globals<rustc_interface[b60702df0ae80ef4]::interface::run_compiler<core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>, rustc_driver_impl[36a7eaa3807b03c1]::run_compiler::{closure#1}>::{closure#0}, core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>
  67:     0x7f048c665fce - <<std[fa39155a576d62c5]::thread::Builder>::spawn_unchecked_<rustc_interface[b60702df0ae80ef4]::util::run_in_thread_pool_with_globals<rustc_interface[b60702df0ae80ef4]::interface::run_compiler<core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>, rustc_driver_impl[36a7eaa3807b03c1]::run_compiler::{closure#1}>::{closure#0}, core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[81c8fe8a09de0f06]::result::Result<(), rustc_span[d4de8c39017ea598]::ErrorGuaranteed>>::{closure#1} as core[81c8fe8a09de0f06]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  68:     0x7f048a171c55 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h83f49025b00909a5
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/alloc/src/boxed.rs:2007:9
  69:     0x7f048a171c55 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h21b0d4679eed4e05
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/alloc/src/boxed.rs:2007:9
  70:     0x7f048a171c55 - std::sys::unix::thread::Thread::new::thread_start::h030641e4e4790460
                               at /rustc/4c8bb79d9f565115637cc6da739f8389e79f3a29/library/std/src/sys/unix/thread.rs:108:17
  71:     0x7f0489f0444b - <unknown>
  72:     0x7f0489f87e40 - <unknown>
  73:                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: rustc 1.73.0-nightly (4c8bb79d9 2023-07-15) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [layout_of] computing layout of `core::mem::maybe_uninit::MaybeUninit<dyn core::iter::traits::iterator::Iterator<Item = {type error}>>`
#1 [layout_of] computing layout of `core::cell::UnsafeCell<core::mem::maybe_uninit::MaybeUninit<dyn core::iter::traits::iterator::Iterator<Item = {type error}>>>`
#2 [layout_of] computing layout of `std::sync::once_lock::OnceLock<dyn core::iter::traits::iterator::Iterator<Item = {type error}>>`
#3 [layout_of] computing layout of `std::sync::once_lock::OnceLock<(dyn core::iter::traits::iterator::Iterator<Item = {type error}> + 'static)>`
#4 [layout_of] computing layout of `WeakOnce<{type error}>`
#5 [check_mod_item_types] checking item types in top-level module
#6 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 6 previous errors

Some errors have detailed explanations: E0106, E0412, E0599, E0601, E0658.
For more information about an error, try `rustc --explain E0106`.

[matthiaskrgr]

Crashes 1.72.0-beta.1 but not stable 1.71.0

Regression in rust-lang-ci@4c221b7
#112340 cc @lcnr

[compiler-errors]

Since this went from error -> ICE (specifically because it's neither valid code, and also would need the associated_type_bounds flag even if it were valid), I don't think this needs prioritization and/or the regression tag.

[compiler-errors]

Minimized too:

union W<T> { s: dyn Iterator<Item = Missing> }

static ONCE: W<()> = todo!();

Or even more minimal:

union W { s: dyn Iterator<Item = Missing> }

static ONCE: W = todo!();

[compiler-errors]

Also, this didn't really regress in #112340. Before that PR, it ICEd with a slighlty different repro:

union W<T> { t: T, s: dyn Iterator<Item = Missing> }

static ONCE: W<()> = todo!();

Specifically, if you get rid of the "parameter T is never used" error by actually mentioning it in that union W above, then it'll ICE even before #112340.

It probably just regressed in whatever PR introduced that assertion that got triggered.