ICE: `Layout::compute: unexpected type '_'`

[Naserume]

Code

pub trait A {}
pub trait B: A {}

pub trait Mirror {
    type Assoc: ?Sized;
}
impl<T: ?Sized> Mirror for A {
    type Assoc = T;
}

pub fn foo<'a>(x: &'a <dyn A + 'static as Mirror>::Assoc) -> &'a <dyn B + 'static as Mirror>::Assoc {
    static
}

static I: <dyn A + 'static as Mirror>::Assoc = 3;
pub fn main() {}

Meta

rustc --version --verbose:

rustc 1.81.0-nightly (bcf94dec5 2024-06-23)
binary: rustc
commit-hash: bcf94dec5ba6838e435902120c0384c360126a26
commit-date: 2024-06-23
host: x86_64-apple-darwin
release: 1.81.0-nightly
LLVM version: 18.1.7

Error output

error: expected identifier, found `}`
  --> ./6EC19.rs:13:1
   |
13 | }
   | ^ expected identifier

warning: trait objects without an explicit `dyn` are deprecated
 --> ./6EC19.rs:7:28
  |
7 | impl<T: ?Sized> Mirror for A {
  |                            ^
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` on by default
help: if this is an object-safe trait, use `dyn`
  |
7 | impl<T: ?Sized> Mirror for dyn A {
  |                            +++
help: alternatively use a blanket implementation to implement `Mirror` for all types that also implement `A`
  |
7 | impl<T: ?Sized, U: A> Mirror for U {
  |               ++++++             ~

error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
 --> ./6EC19.rs:7:6
  |
7 | impl<T: ?Sized> Mirror for A {
  |      ^ unconstrained type parameter

error[E0277]: the trait bound `(dyn B + 'static): Mirror` is not satisfied
  --> ./6EC19.rs:11:62
   |
11 | pub fn foo<'a>(x: &'a <dyn A + 'static as Mirror>::Assoc) -> &'a <dyn B + 'static as Mirror>::Assoc {
   |                                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Mirror` is not implemented for `(dyn B + 'static)`
   |
   = help: the trait `Mirror` is implemented for `(dyn A + 'static)`

error[E0283]: type annotations needed
  --> ./6EC19.rs:15:11
   |
15 | static I: <dyn A + 'static as Mirror>::Assoc = 3;
   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`
   |
   = note: cannot satisfy `_: Sync`
   = note: shared static variables must have a type that implements `Sync`

Backtrace

error: internal compiler error: compiler/rustc_ty_utils/src/layout.rs:674:13: Layout::compute: unexpected type `_`

thread 'rustc' panicked at compiler/rustc_ty_utils/src/layout.rs:674:13:
Box<dyn Any>
stack backtrace:
   0:        0x10cae6b43 - <std::sys::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::he71f7af0ddafc64d
   1:        0x10cb3225b - core::fmt::write::h30d0e266faff29b6
   2:        0x10cadcace - std::io::Write::write_fmt::he666ca78eb4b8406
   3:        0x10cae6931 - std::sys::backtrace::print::h22721f9ab9a2749a
   4:        0x10cae9709 - std::panicking::default_hook::{{closure}}::h145e29ed875d8021
   5:        0x10cae948a - std::panicking::default_hook::h5d437c7e6bf0e3b5
   6:        0x115d8147c - std[8efa578c02603ef9]::panicking::update_hook::<alloc[135510a28be92df]::boxed::Box<rustc_driver_impl[63f2171535a6fe49]::install_ice_hook::{closure#0}>>::{closure#0}
   7:        0x10caea326 - std::panicking::rust_panic_with_hook::h6889093a56e48d04
   8:        0x115df0337 - std[8efa578c02603ef9]::panicking::begin_panic::<rustc_errors[8995f93e9c4bcc9a]::ExplicitBug>::{closure#0}
   9:        0x115ddc949 - std[8efa578c02603ef9]::sys::backtrace::__rust_end_short_backtrace::<std[8efa578c02603ef9]::panicking::begin_panic<rustc_errors[8995f93e9c4bcc9a]::ExplicitBug>::{closure#0}, !>
  10:        0x11a7e2f09 - std[8efa578c02603ef9]::panicking::begin_panic::<rustc_errors[8995f93e9c4bcc9a]::ExplicitBug>
  11:        0x115e02276 - <rustc_errors[8995f93e9c4bcc9a]::diagnostic::BugAbort as rustc_errors[8995f93e9c4bcc9a]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:        0x116a9c95e - rustc_middle[4384e439927f71dd]::util::bug::opt_span_bug_fmt::<rustc_span[aed5394308446158]::span_encoding::Span>::{closure#0}
  13:        0x116a522b7 - rustc_middle[4384e439927f71dd]::ty::context::tls::with_opt::<rustc_middle[4384e439927f71dd]::util::bug::opt_span_bug_fmt<rustc_span[aed5394308446158]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:        0x116a51d75 - rustc_middle[4384e439927f71dd]::ty::context::tls::with_context_opt::<rustc_middle[4384e439927f71dd]::ty::context::tls::with_opt<rustc_middle[4384e439927f71dd]::util::bug::opt_span_bug_fmt<rustc_span[aed5394308446158]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:        0x11a8a57eb - rustc_middle[4384e439927f71dd]::util::bug::bug_fmt
  16:        0x117bc12e7 - rustc_ty_utils[a4413d16294df763]::layout::layout_of_uncached
  17:        0x117bd4076 - rustc_ty_utils[a4413d16294df763]::layout::layout_of
  18:        0x117423276 - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 16usize]>>
  19:        0x1173f2f4e - <rustc_query_impl[a24e9023943e74ab]::query_impl::layout_of::dynamic_query::{closure#2} as core[9412a59d758dca42]::ops::function::FnOnce<(rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::ty::Ty>)>>::call_once
  20:        0x11720a655 - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::ty::Ty>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  21:        0x1174613f4 - rustc_query_impl[a24e9023943e74ab]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  22:        0x117b59d59 - rustc_middle[4384e439927f71dd]::query::plumbing::query_get_at::<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::ty::Ty>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 16usize]>>>
  23:        0x117bd4051 - rustc_ty_utils[a4413d16294df763]::layout::layout_of
  24:        0x117423276 - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 16usize]>>
  25:        0x1173f2f4e - <rustc_query_impl[a24e9023943e74ab]::query_impl::layout_of::dynamic_query::{closure#2} as core[9412a59d758dca42]::ops::function::FnOnce<(rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::ty::Ty>)>>::call_once
  26:        0x11720a655 - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::ty::Ty>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  27:        0x1174613f4 - rustc_query_impl[a24e9023943e74ab]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  28:        0x115fac0a6 - rustc_middle[4384e439927f71dd]::query::plumbing::query_get_at::<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::ty::Ty>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 16usize]>>>
  29:        0x11607bd51 - rustc_hir_analysis[8e62bc6471a04889]::check::check::check_static_inhabited
  30:        0x11607f85d - rustc_hir_analysis[8e62bc6471a04889]::check::check::check_item_type
  31:        0x1160b64ae - rustc_hir_analysis[8e62bc6471a04889]::check::wfcheck::check_well_formed
  32:        0x11741e86c - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>
  33:        0x11729701f - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::VecCache<rustc_hir[ae2456c39d7f6170]::hir_id::OwnerId, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  34:        0x117468280 - rustc_query_impl[a24e9023943e74ab]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  35:        0x115facba2 - rustc_middle[4384e439927f71dd]::query::plumbing::query_ensure_error_guaranteed::<rustc_query_system[30bd0146b5104221]::query::caches::VecCache<rustc_hir[ae2456c39d7f6170]::hir_id::OwnerId, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>, ()>
  36:        0x1160c4de1 - rustc_hir_analysis[8e62bc6471a04889]::check::wfcheck::check_mod_type_wf
  37:        0x11741e83c - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>
  38:        0x11724db79 - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_span[aed5394308446158]::def_id::LocalModDefId, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  39:        0x117444ed0 - rustc_query_impl[a24e9023943e74ab]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  40:        0x11614024c - rustc_hir_analysis[8e62bc6471a04889]::check_crate
  41:        0x1166da6cb - rustc_interface[73216d77aad0c3a5]::passes::run_required_analyses
  42:        0x1166dccb3 - rustc_interface[73216d77aad0c3a5]::passes::analysis
  43:        0x117422dec - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>
  44:        0x11720249e - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::SingleCache<rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  45:        0x11742d307 - rustc_query_impl[a24e9023943e74ab]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  46:        0x115d258d7 - <rustc_interface[73216d77aad0c3a5]::queries::QueryResult<&rustc_middle[4384e439927f71dd]::ty::context::GlobalCtxt>>::enter::<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}::{closure#1}::{closure#3}>
  47:        0x115d7fc94 - rustc_interface[73216d77aad0c3a5]::interface::run_compiler::<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}>::{closure#1}
  48:        0x115d6ec91 - std[8efa578c02603ef9]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_with_globals<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_pool_with_globals<rustc_interface[73216d77aad0c3a5]::interface::run_compiler<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}>::{closure#1}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>
  49:        0x115d8a3a6 - <<std[8efa578c02603ef9]::thread::Builder>::spawn_unchecked_<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_with_globals<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_pool_with_globals<rustc_interface[73216d77aad0c3a5]::interface::run_compiler<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}>::{closure#1}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#2} as core[9412a59d758dca42]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  50:        0x10caf352b - std::sys::pal::unix::thread::Thread::new::thread_start::h68d49fa26efc1659
  51:     0x7ff801f5318b - __pthread_start

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 `/Users/Documents/240624-56257.txt` to your bug report

query stack during panic:
panicked at /rustc/bcf94dec5ba6838e435902120c0384c360126a26/compiler/rustc_type_ir/src/ty_kind.rs:889:17:

thread panicked while processing panic. aborting.
zsh: abort      rustc ./6EC19.rs

Similar Issue

Issue #124207 has same ice message with similar backtrace, but this require #![feature(transmutability)] and #![feature(type_alias_impl_trait)] because it uses BikeshedIntrinsicsFrom so I decided to report mine.

[GrigorenkoPV]

searched nightlies: from nightly-2022-02-19 to nightly-2024-06-25
regressed nightly: nightly-2024-03-08
searched commit range: 7d3702e...9c3ad80
regressed commit: 8c9a75b (#121154)

[theemathas]

Minimized:

struct Thing;

pub trait Every {
    type Assoc;
}
impl<T: ?Sized> Every for Thing {
    type Assoc = T;
}

static I: <Thing as Every>::Assoc = 3;

Error output

   Compiling playground v0.0.1 (/playground)
error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
 --> src/lib.rs:6:6
  |
6 | impl<T: ?Sized> Every for Thing {
  |      ^ unconstrained type parameter

error[E0283]: type annotations needed
  --> src/lib.rs:10:11
   |
10 | static I: <Thing as Every>::Assoc = 3;
   |           ^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`
   |
   = note: cannot satisfy `_: Sync`
   = note: shared static variables must have a type that implements `Sync`

error: internal compiler error: compiler/rustc_ty_utils/src/layout.rs:676:13: Layout::compute: unexpected type `_`

thread 'rustc' panicked at compiler/rustc_ty_utils/src/layout.rs:676:13:
Box<dyn Any>
stack backtrace:
   0:     0x7f5be3c9b035 - std::backtrace_rs::backtrace::libunwind::trace::h1a07e5dba0da0cd2
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x7f5be3c9b035 - std::backtrace_rs::backtrace::trace_unsynchronized::h61b9b8394328c0bc
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f5be3c9b035 - std::sys_common::backtrace::_print_fmt::h1c5e18b460934cff
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f5be3c9b035 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e1a1972118942ad
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f5be3cea29b - core::fmt::rt::Argument::fmt::h07af2b4071d536cd
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/rt.rs:165:63
   5:     0x7f5be3cea29b - core::fmt::write::hc090a2ffd6b28c4a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/mod.rs:1157:21
   6:     0x7f5be3c8fbdf - std::io::Write::write_fmt::h8898bac6ff039a23
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/io/mod.rs:1832:15
   7:     0x7f5be3c9ae0e - std::sys_common::backtrace::_print::h4e80c5803d4ee35b
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f5be3c9ae0e - std::sys_common::backtrace::print::ha96650907276675e
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f5be3c9d779 - std::panicking::default_hook::{{closure}}::h215c2a0a8346e0e0
  10:     0x7f5be3c9d4bd - std::panicking::default_hook::h207342be97478370
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:298:9
  11:     0x7f5be6b981b7 - std[3c8ba8ebcf555201]::panicking::update_hook::<alloc[bfbae7e348dce413]::boxed::Box<rustc_driver_impl[c88438ade88661f4]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f5be3c9de76 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::ha9c3bc81d312fd83
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2036:9
  13:     0x7f5be3c9de76 - std::panicking::rust_panic_with_hook::hac8bdceee1e4fe2c
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:799:13
  14:     0x7f5be6bc5b44 - std[3c8ba8ebcf555201]::panicking::begin_panic::<rustc_errors[80cf825e20fac581]::ExplicitBug>::{closure#0}
  15:     0x7f5be6bc24f6 - std[3c8ba8ebcf555201]::sys_common::backtrace::__rust_end_short_backtrace::<std[3c8ba8ebcf555201]::panicking::begin_panic<rustc_errors[80cf825e20fac581]::ExplicitBug>::{closure#0}, !>
  16:     0x7f5be6bbdb66 - std[3c8ba8ebcf555201]::panicking::begin_panic::<rustc_errors[80cf825e20fac581]::ExplicitBug>
  17:     0x7f5be6bcef01 - <rustc_errors[80cf825e20fac581]::diagnostic::BugAbort as rustc_errors[80cf825e20fac581]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x7f5be7048b1c - rustc_middle[3ff731b746e7b038]::util::bug::opt_span_bug_fmt::<rustc_span[8c7415e9d33ddd75]::span_encoding::Span>::{closure#0}
  19:     0x7f5be702fc2a - rustc_middle[3ff731b746e7b038]::ty::context::tls::with_opt::<rustc_middle[3ff731b746e7b038]::util::bug::opt_span_bug_fmt<rustc_span[8c7415e9d33ddd75]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7f5be702facb - rustc_middle[3ff731b746e7b038]::ty::context::tls::with_context_opt::<rustc_middle[3ff731b746e7b038]::ty::context::tls::with_opt<rustc_middle[3ff731b746e7b038]::util::bug::opt_span_bug_fmt<rustc_span[8c7415e9d33ddd75]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7f5be4da0740 - rustc_middle[3ff731b746e7b038]::util::bug::bug_fmt
  22:     0x7f5be855b842 - rustc_ty_utils[b79b74a9f824867d]::layout::layout_of_uncached
  23:     0x7f5be854d990 - rustc_ty_utils[b79b74a9f824867d]::layout::layout_of
  24:     0x7f5be854d911 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 16usize]>>
  25:     0x7f5be854d0bd - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  26:     0x7f5be854cdb2 - rustc_query_impl[a12402620de91e8]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  27:     0x7f5be855fc0a - rustc_middle[3ff731b746e7b038]::query::plumbing::query_get_at::<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 16usize]>>>
  28:     0x7f5be854db59 - rustc_ty_utils[b79b74a9f824867d]::layout::layout_of
  29:     0x7f5be854d911 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 16usize]>>
  30:     0x7f5be854d0bd - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  31:     0x7f5be854cdb2 - rustc_query_impl[a12402620de91e8]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  32:     0x7f5be8dafaec - rustc_middle[3ff731b746e7b038]::query::plumbing::query_get_at::<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 16usize]>>>
  33:     0x7f5be8daf63b - rustc_hir_analysis[46a17d8846b4335f]::check::check::check_static_inhabited
  34:     0x7f5be8db4fa0 - rustc_hir_analysis[46a17d8846b4335f]::check::check::check_item_type
  35:     0x7f5be84da627 - rustc_hir_analysis[46a17d8846b4335f]::check::wfcheck::check_well_formed
  36:     0x7f5be84d923d - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  37:     0x7f5be84d8de3 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::VecCache<rustc_hir[809d8cc19d3b2ead]::hir_id::OwnerId, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  38:     0x7f5be84d8b99 - rustc_query_impl[a12402620de91e8]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  39:     0x7f5be84d6e95 - rustc_hir_analysis[46a17d8846b4335f]::check::wfcheck::check_mod_type_wf
  40:     0x7f5be84d6d49 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  41:     0x7f5be8b12210 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_span[8c7415e9d33ddd75]::def_id::LocalModDefId, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  42:     0x7f5be8b11fff - rustc_query_impl[a12402620de91e8]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  43:     0x7f5be86d91d0 - rustc_hir_analysis[46a17d8846b4335f]::check_crate
  44:     0x7f5be88980e0 - rustc_interface[640972162e3c086f]::passes::analysis
  45:     0x7f5be8897aef - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  46:     0x7f5be8bf1022 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::SingleCache<rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  47:     0x7f5be8bf0dc9 - rustc_query_impl[a12402620de91e8]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  48:     0x7f5be8a92149 - rustc_interface[640972162e3c086f]::interface::run_compiler::<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}
  49:     0x7f5be8a4ff8b - std[3c8ba8ebcf555201]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>
  50:     0x7f5be8a4fd80 - <<std[3c8ba8ebcf555201]::thread::Builder>::spawn_unchecked_<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#2} as core[868bc93c3f2beb33]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  51:     0x7f5be3ca7cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h09e5a4c541afa800
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  52:     0x7f5be3ca7cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9c8b03c22f4e7026
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  53:     0x7f5be3ca7cab - std::sys::pal::unix::thread::Thread::new::thread_start::h522bc89a54da820a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys/pal/unix/thread.rs:108:17
  54:     0x7f5be3bb5609 - start_thread
  55:     0x7f5be3ad8353 - clone
  56:                0x0 - <unknown>

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 1.79.0 (129f3b996 2024-06-10) running on x86_64-unknown-linux-gnu

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 [layout_of] computing layout of `_`
#1 [layout_of] computing layout of `<Thing as Every>::Assoc`
#2 [check_well_formed] checking that `I` is well-formed
#3 [check_mod_type_wf] checking that types are well-formed in top-level module
#4 [analysis] running analysis passes on this crate
end of query stack
Some errors have detailed explanations: E0207, E0283.
For more information about an error, try `rustc --explain E0207`.
error: could not compile `playground` (lib) due to 2 previous errors

[theemathas]

Variant with a different ICE (index out of bounds: the len is 0 but the index is 0)

struct Thing;

pub trait Every {
    type Assoc;
}
impl<T: ?Sized> Every for Thing {
    type Assoc = T;
}

fn foo(_: <Thing as Every>::Assoc) {}

Error output

   Compiling playground v0.0.1 (/playground)
error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
 --> src/lib.rs:6:6
  |
6 | impl<T: ?Sized> Every for Thing {
  |      ^ unconstrained type parameter

error[E0282]: type annotations needed
  --> src/lib.rs:10:11
   |
10 | fn foo(_: <Thing as Every>::Assoc) {}
   |           ^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`

error[E0282]: type annotations needed
  --> src/lib.rs:10:8
   |
10 | fn foo(_: <Thing as Every>::Assoc) {}
   |        ^ cannot infer type for type parameter `T`

thread 'rustc' panicked at /rust/deps/ena-0.14.2/src/snapshot_vec.rs:199:10:
index out of bounds: the len is 0 but the index is 0
stack backtrace:
   0:     0x7f0d4f6d5035 - std::backtrace_rs::backtrace::libunwind::trace::h1a07e5dba0da0cd2
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x7f0d4f6d5035 - std::backtrace_rs::backtrace::trace_unsynchronized::h61b9b8394328c0bc
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f0d4f6d5035 - std::sys_common::backtrace::_print_fmt::h1c5e18b460934cff
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f0d4f6d5035 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e1a1972118942ad
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f0d4f72429b - core::fmt::rt::Argument::fmt::h07af2b4071d536cd
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/rt.rs:165:63
   5:     0x7f0d4f72429b - core::fmt::write::hc090a2ffd6b28c4a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/mod.rs:1157:21
   6:     0x7f0d4f6c9bdf - std::io::Write::write_fmt::h8898bac6ff039a23
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/io/mod.rs:1832:15
   7:     0x7f0d4f6d4e0e - std::sys_common::backtrace::_print::h4e80c5803d4ee35b
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f0d4f6d4e0e - std::sys_common::backtrace::print::ha96650907276675e
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f0d4f6d7779 - std::panicking::default_hook::{{closure}}::h215c2a0a8346e0e0
  10:     0x7f0d4f6d74bd - std::panicking::default_hook::h207342be97478370
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:298:9
  11:     0x7f0d525d21b7 - std[3c8ba8ebcf555201]::panicking::update_hook::<alloc[bfbae7e348dce413]::boxed::Box<rustc_driver_impl[c88438ade88661f4]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f0d4f6d7e76 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::ha9c3bc81d312fd83
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2036:9
  13:     0x7f0d4f6d7e76 - std::panicking::rust_panic_with_hook::hac8bdceee1e4fe2c
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:799:13
  14:     0x7f0d4f6d7c24 - std::panicking::begin_panic_handler::{{closure}}::h00d785e82757ce3c
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:664:13
  15:     0x7f0d4f6d54f9 - std::sys_common::backtrace::__rust_end_short_backtrace::h1628d957bcd06996
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7f0d4f6d7957 - rust_begin_unwind
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:652:5
  17:     0x7f0d4f720763 - core::panicking::panic_fmt::hdc63834ffaaefae5
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:72:14
  18:     0x7f0d4f720987 - core::panicking::panic_bounds_check::hd7e618b1b39cc1c3
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:275:5
  19:     0x7f0d54a5f768 - <ena[7ba0c23a1613b29]::unify::UnificationTable<ena[7ba0c23a1613b29]::unify::backing_vec::InPlace<rustc_infer[abd41066181445be]::infer::type_variable::TyVidEqKey, &mut alloc[bfbae7e348dce413]::vec::Vec<ena[7ba0c23a1613b29]::unify::VarValue<rustc_infer[abd41066181445be]::infer::type_variable::TyVidEqKey>>, &mut rustc_infer[abd41066181445be]::infer::snapshot::undo_log::InferCtxtUndoLogs>>>::uninlined_get_root_key.llvm.6537034541696690420.cold
  20:     0x7f0d507a0045 - <rustc_infer[abd41066181445be]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[a145be3c51398263]::fold::TypeFolder<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt>>::fold_ty
  21:     0x7f0d53dd6b38 - <rustc_infer[abd41066181445be]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[a145be3c51398263]::fold::FallibleTypeFolder<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt>>::try_fold_predicate
  22:     0x7f0d5115701f - rustc_trait_selection[173dcaf5d960508e]::traits::type_known_to_meet_bound_modulo_regions
  23:     0x7f0d53ba840b - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::is_copy_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  24:     0x7f0d53ba93c6 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  25:     0x7f0d53ba90ce - rustc_query_impl[a12402620de91e8]::query_impl::is_copy_raw::get_query_non_incr::__rust_end_short_backtrace
  26:     0x7f0d53baa0eb - rustc_ty_utils[b79b74a9f824867d]::needs_drop::needs_drop_raw
  27:     0x7f0d53ba9b59 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::needs_drop_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  28:     0x7f0d53ba936a - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  29:     0x7f0d53ba900e - rustc_query_impl[a12402620de91e8]::query_impl::needs_drop_raw::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7f0d50b12f93 - <rustc_mir_transform[2984d3182075647]::elaborate_drops::ElaborateDrops as rustc_middle[3ff731b746e7b038]::mir::MirPass>::run_pass
  31:     0x7f0d5394a4cd - rustc_mir_transform[2984d3182075647]::pass_manager::run_passes_inner
  32:     0x7f0d5141bff7 - rustc_mir_transform[2984d3182075647]::mir_drops_elaborated_and_const_checked
  33:     0x7f0d53a5ec31 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>
  34:     0x7f0d53a5ef2d - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::VecCache<rustc_span[8c7415e9d33ddd75]::def_id::LocalDefId, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  35:     0x7f0d53a5e78c - rustc_query_impl[a12402620de91e8]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7f0d542d2432 - rustc_interface[640972162e3c086f]::passes::analysis
  37:     0x7f0d542d1aef - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  38:     0x7f0d5462b022 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::SingleCache<rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  39:     0x7f0d5462adc9 - rustc_query_impl[a12402620de91e8]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  40:     0x7f0d544cc149 - rustc_interface[640972162e3c086f]::interface::run_compiler::<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}
  41:     0x7f0d54489f8b - std[3c8ba8ebcf555201]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>
  42:     0x7f0d54489d80 - <<std[3c8ba8ebcf555201]::thread::Builder>::spawn_unchecked_<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#2} as core[868bc93c3f2beb33]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7f0d4f6e1cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h09e5a4c541afa800
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  44:     0x7f0d4f6e1cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9c8b03c22f4e7026
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  45:     0x7f0d4f6e1cab - std::sys::pal::unix::thread::Thread::new::thread_start::h522bc89a54da820a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys/pal/unix/thread.rs:108:17
  46:     0x7f0d4f5ef609 - start_thread
  47:     0x7f0d4f512353 - clone
  48:                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 1.79.0 (129f3b996 2024-06-10) running on x86_64-unknown-linux-gnu

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 [is_copy_raw] computing whether `_` is `Copy`
#1 [needs_drop_raw] computing whether `_` needs drop
#2 [mir_drops_elaborated_and_const_checked] elaborating drops for `foo`
#3 [analysis] running analysis passes on this crate
end of query stack
Some errors have detailed explanations: E0207, E0282.
For more information about an error, try `rustc --explain E0207`.
error: could not compile `playground` (lib) due to 3 previous errors

Removing the ?Sized makes the ICE go away for some reason.

[gurry]

Minimized:

struct Thing;

pub trait Every {
    type Assoc;
}
impl<T: ?Sized> Every for Thing {
    type Assoc = T;
}

static I: <Thing as Every>::Assoc = 3;

I investigated using the above code. The ICE occurs when we call the layout query during the inhabitedness check for the static I. Given the assignment to 3 in the declaration static I: <Thing as Every>::Assoc = 3 its type should normalize and resolve to i32 or something, but because we have a T: ?Size constraint in the impl that is not possible. So we get back a tykind Infer instead. When that Infer type is passed to layout_of_uncached it ICEs.

That explains why removing the ?Sized constraint makes the issue go away.

@rustbot claim

[gurry]

Variant with a different ICE (index out of bounds: the len is 0 but the index is 0)

struct Thing;

pub trait Every {
    type Assoc;
}
impl<T: ?Sized> Every for Thing {
    type Assoc = T;
}

fn foo(_: <Thing as Every>::Assoc) {}

Error output

   Compiling playground v0.0.1 (/playground)
error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
 --> src/lib.rs:6:6
  |
6 | impl<T: ?Sized> Every for Thing {
  |      ^ unconstrained type parameter

error[E0282]: type annotations needed
  --> src/lib.rs:10:11
   |
10 | fn foo(_: <Thing as Every>::Assoc) {}
   |           ^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`

error[E0282]: type annotations needed
  --> src/lib.rs:10:8
   |
10 | fn foo(_: <Thing as Every>::Assoc) {}
   |        ^ cannot infer type for type parameter `T`

thread 'rustc' panicked at /rust/deps/ena-0.14.2/src/snapshot_vec.rs:199:10:
index out of bounds: the len is 0 but the index is 0
stack backtrace:
   0:     0x7f0d4f6d5035 - std::backtrace_rs::backtrace::libunwind::trace::h1a07e5dba0da0cd2
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x7f0d4f6d5035 - std::backtrace_rs::backtrace::trace_unsynchronized::h61b9b8394328c0bc
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f0d4f6d5035 - std::sys_common::backtrace::_print_fmt::h1c5e18b460934cff
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f0d4f6d5035 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e1a1972118942ad
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f0d4f72429b - core::fmt::rt::Argument::fmt::h07af2b4071d536cd
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/rt.rs:165:63
   5:     0x7f0d4f72429b - core::fmt::write::hc090a2ffd6b28c4a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/mod.rs:1157:21
   6:     0x7f0d4f6c9bdf - std::io::Write::write_fmt::h8898bac6ff039a23
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/io/mod.rs:1832:15
   7:     0x7f0d4f6d4e0e - std::sys_common::backtrace::_print::h4e80c5803d4ee35b
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f0d4f6d4e0e - std::sys_common::backtrace::print::ha96650907276675e
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f0d4f6d7779 - std::panicking::default_hook::{{closure}}::h215c2a0a8346e0e0
  10:     0x7f0d4f6d74bd - std::panicking::default_hook::h207342be97478370
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:298:9
  11:     0x7f0d525d21b7 - std[3c8ba8ebcf555201]::panicking::update_hook::<alloc[bfbae7e348dce413]::boxed::Box<rustc_driver_impl[c88438ade88661f4]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f0d4f6d7e76 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::ha9c3bc81d312fd83
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2036:9
  13:     0x7f0d4f6d7e76 - std::panicking::rust_panic_with_hook::hac8bdceee1e4fe2c
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:799:13
  14:     0x7f0d4f6d7c24 - std::panicking::begin_panic_handler::{{closure}}::h00d785e82757ce3c
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:664:13
  15:     0x7f0d4f6d54f9 - std::sys_common::backtrace::__rust_end_short_backtrace::h1628d957bcd06996
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7f0d4f6d7957 - rust_begin_unwind
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:652:5
  17:     0x7f0d4f720763 - core::panicking::panic_fmt::hdc63834ffaaefae5
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:72:14
  18:     0x7f0d4f720987 - core::panicking::panic_bounds_check::hd7e618b1b39cc1c3
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:275:5
  19:     0x7f0d54a5f768 - <ena[7ba0c23a1613b29]::unify::UnificationTable<ena[7ba0c23a1613b29]::unify::backing_vec::InPlace<rustc_infer[abd41066181445be]::infer::type_variable::TyVidEqKey, &mut alloc[bfbae7e348dce413]::vec::Vec<ena[7ba0c23a1613b29]::unify::VarValue<rustc_infer[abd41066181445be]::infer::type_variable::TyVidEqKey>>, &mut rustc_infer[abd41066181445be]::infer::snapshot::undo_log::InferCtxtUndoLogs>>>::uninlined_get_root_key.llvm.6537034541696690420.cold
  20:     0x7f0d507a0045 - <rustc_infer[abd41066181445be]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[a145be3c51398263]::fold::TypeFolder<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt>>::fold_ty
  21:     0x7f0d53dd6b38 - <rustc_infer[abd41066181445be]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[a145be3c51398263]::fold::FallibleTypeFolder<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt>>::try_fold_predicate
  22:     0x7f0d5115701f - rustc_trait_selection[173dcaf5d960508e]::traits::type_known_to_meet_bound_modulo_regions
  23:     0x7f0d53ba840b - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::is_copy_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  24:     0x7f0d53ba93c6 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  25:     0x7f0d53ba90ce - rustc_query_impl[a12402620de91e8]::query_impl::is_copy_raw::get_query_non_incr::__rust_end_short_backtrace
  26:     0x7f0d53baa0eb - rustc_ty_utils[b79b74a9f824867d]::needs_drop::needs_drop_raw
  27:     0x7f0d53ba9b59 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::needs_drop_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  28:     0x7f0d53ba936a - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::Ty>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  29:     0x7f0d53ba900e - rustc_query_impl[a12402620de91e8]::query_impl::needs_drop_raw::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7f0d50b12f93 - <rustc_mir_transform[2984d3182075647]::elaborate_drops::ElaborateDrops as rustc_middle[3ff731b746e7b038]::mir::MirPass>::run_pass
  31:     0x7f0d5394a4cd - rustc_mir_transform[2984d3182075647]::pass_manager::run_passes_inner
  32:     0x7f0d5141bff7 - rustc_mir_transform[2984d3182075647]::mir_drops_elaborated_and_const_checked
  33:     0x7f0d53a5ec31 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>
  34:     0x7f0d53a5ef2d - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::VecCache<rustc_span[8c7415e9d33ddd75]::def_id::LocalDefId, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  35:     0x7f0d53a5e78c - rustc_query_impl[a12402620de91e8]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7f0d542d2432 - rustc_interface[640972162e3c086f]::passes::analysis
  37:     0x7f0d542d1aef - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  38:     0x7f0d5462b022 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::SingleCache<rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  39:     0x7f0d5462adc9 - rustc_query_impl[a12402620de91e8]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  40:     0x7f0d544cc149 - rustc_interface[640972162e3c086f]::interface::run_compiler::<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}
  41:     0x7f0d54489f8b - std[3c8ba8ebcf555201]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>
  42:     0x7f0d54489d80 - <<std[3c8ba8ebcf555201]::thread::Builder>::spawn_unchecked_<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#2} as core[868bc93c3f2beb33]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7f0d4f6e1cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h09e5a4c541afa800
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  44:     0x7f0d4f6e1cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9c8b03c22f4e7026
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  45:     0x7f0d4f6e1cab - std::sys::pal::unix::thread::Thread::new::thread_start::h522bc89a54da820a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys/pal/unix/thread.rs:108:17
  46:     0x7f0d4f5ef609 - start_thread
  47:     0x7f0d4f512353 - clone
  48:                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 1.79.0 (129f3b996 2024-06-10) running on x86_64-unknown-linux-gnu

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 [is_copy_raw] computing whether `_` is `Copy`
#1 [needs_drop_raw] computing whether `_` needs drop
#2 [mir_drops_elaborated_and_const_checked] elaborating drops for `foo`
#3 [analysis] running analysis passes on this crate
end of query stack
Some errors have detailed explanations: E0207, E0282.
For more information about an error, try `rustc --explain E0207`.
error: could not compile `playground` (lib) due to 3 previous errors

Removing the ?Sized makes the ICE go away for some reason.

This is a completely different ICE. I have opened a separate issue for it: #127804