[ICE]: failed to resolve instance for <bool as Droppable>::drop #154073

rustc 1.94.0 (4a4ef493e 2026-03-02)
binary: rustc
commit-hash: 4a4ef493e3a1488c6e321570238084b38948f6db
commit-date: 2026-03-02
host: x86_64-unknown-linux-gnu
release: 1.94.0
LLVM version: 21.1.8

error[E0277]: the trait bound `T: Droppable` is not satisfied
 --> bug.rs:2:26
  |
2 | impl<T: Send + > Bar for T {}
  |                          ^ the trait `Droppable` is not implemented for `T`
  |
note: required by a bound in `Bar`
 --> bug.rs:1:26
  |
1 | trait Bar: Send + Sync + Droppable {}
  |                          ^^^^^^^^^ required by this bound in `Bar`
help: consider further restricting type parameter `T` with trait `Droppable`
  |
2 | impl<T: Send + Droppable + > Bar for T {}
  |              +++++++++++

error[E0277]: `T` cannot be shared between threads safely
 --> bug.rs:2:26
  |
2 | impl<T: Send + > Bar for T {}
  |                          ^ `T` cannot be shared between threads safely
  |
note: required by a bound in `Bar`
 --> bug.rs:1:19
  |
1 | trait Bar: Send + Sync + Droppable {}
  |                   ^^^^ required by this bound in `Bar`
help: consider further restricting type parameter `T` with trait `Sync`
  |
2 | impl<T: Send + std::marker::Sync + > Bar for T {}
  |              +++++++++++++++++++

warning: trait objects without an explicit `dyn` are deprecated
 --> bug.rs:6:32
  |
6 | const fn yeet_principal_4(x: & Bar) -> &( Send + Sync) {
  |                                ^^^
  |
  = 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/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` (part of `#[warn(rust_2021_compatibility)]`) on by default
help: if this is a dyn-compatible trait, use `dyn`
  |
6 | const fn yeet_principal_4(x: & dyn Bar) -> &( Send + Sync) {
  |                                +++

warning: trait objects without an explicit `dyn` are deprecated
 --> bug.rs:6:43
  |
6 | const fn yeet_principal_4(x: & Bar) -> &( Send + Sync) {
  |                                           ^^^^^^^^^^^
  |
  = 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/edition-guide/rust-2021/warnings-promoted-to-error.html>
help: if this is a dyn-compatible trait, use `dyn`
  |
6 | const fn yeet_principal_4(x: & Bar) -> &( dyn Send + Sync) {
  |                                           +++

warning: trait objects without an explicit `dyn` are deprecated
 --> bug.rs:9:16
  |
9 | static BAR: &( Send + Sync) = yeet_principal_4(&false);
  |                ^^^^^^^^^^^
  |
  = 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/edition-guide/rust-2021/warnings-promoted-to-error.html>
help: if this is a dyn-compatible trait, use `dyn`
  |
9 | static BAR: &( dyn Send + Sync) = yeet_principal_4(&false);
  |                +++

error: internal compiler error: /rustc-dev/4a4ef493e3a1488c6e321570238084b38948f6db/compiler/rustc_middle/src/ty/instance.rs:579:21: failed to resolve instance for <bool as Droppable>::drop
 --> bug.rs:4:5
  |
4 |     fn drop(& self);
  |     ^^^^^^^^^^^^^^^^


thread 'rustc' (1932416) panicked at /rustc-dev/4a4ef493e3a1488c6e321570238084b38948f6db/compiler/rustc_middle/src/ty/instance.rs:579:21:
Box<dyn Any>
stack backtrace:
   0:     0x7f1f5015f603 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h93773fc827e3113d
   1:     0x7f1f50711488 - core::fmt::write::hed7b5c73d82ecb7c
   2:     0x7f1f51bfb142 - std::io::Write::write_fmt::h6f0185aecf0ed75f
   3:     0x7f1f5012cb65 - std::panicking::default_hook::{{closure}}::h2be84df4f189ae36
   4:     0x7f1f5012c993 - std::panicking::default_hook::hf0ea8939246f43a9
   5:     0x7f1f4f113aea - std[765ed69a96918746]::panicking::update_hook::<alloc[7a43974b6697a11c]::boxed::Box<rustc_driver_impl[252c3262fddb99f]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7f1f5012ce92 - std::panicking::panic_with_hook::hb4bd9ac1123582a0
   7:     0x7f1f4f150e01 - std[765ed69a96918746]::panicking::begin_panic::<rustc_errors[45351c624685c6c4]::ExplicitBug>::{closure#0}
   8:     0x7f1f4f141226 - std[765ed69a96918746]::sys::backtrace::__rust_end_short_backtrace::<std[765ed69a96918746]::panicking::begin_panic<rustc_errors[45351c624685c6c4]::ExplicitBug>::{closure#0}, !>
   9:     0x7f1f4f140ebf - std[765ed69a96918746]::panicking::begin_panic::<rustc_errors[45351c624685c6c4]::ExplicitBug>
  10:     0x7f1f4f16eb41 - <rustc_errors[45351c624685c6c4]::diagnostic::BugAbort as rustc_errors[45351c624685c6c4]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7f1f4f7016bc - <rustc_errors[45351c624685c6c4]::DiagCtxtHandle>::span_bug::<rustc_span[56e001752d96add4]::span_encoding::Span, alloc[7a43974b6697a11c]::string::String>
  12:     0x7f1f4f724246 - rustc_middle[f9db403ed88df217]::util::bug::opt_span_bug_fmt::<rustc_span[56e001752d96add4]::span_encoding::Span>::{closure#0}
  13:     0x7f1f4f7243f2 - rustc_middle[f9db403ed88df217]::ty::context::tls::with_opt::<rustc_middle[f9db403ed88df217]::util::bug::opt_span_bug_fmt<rustc_span[56e001752d96add4]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7f1f4f715a1b - rustc_middle[f9db403ed88df217]::ty::context::tls::with_context_opt::<rustc_middle[f9db403ed88df217]::ty::context::tls::with_opt<rustc_middle[f9db403ed88df217]::util::bug::opt_span_bug_fmt<rustc_span[56e001752d96add4]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7f1f4d773498 - rustc_middle[f9db403ed88df217]::util::bug::span_bug_fmt::<rustc_span[56e001752d96add4]::span_encoding::Span>
  16:     0x7f1f50dce1e3 - <rustc_middle[f9db403ed88df217]::ty::instance::Instance>::expect_resolve
  17:     0x7f1f515eee21 - <rustc_middle[f9db403ed88df217]::ty::instance::Instance>::expect_resolve_for_vtable
  18:     0x7f1f515ee30d - rustc_trait_selection[f276006b73549ef0]::traits::vtable::vtable_entries::{closure#0}
  19:     0x7f1f515efa77 - rustc_trait_selection[f276006b73549ef0]::traits::vtable::vtable_entries
  20:     0x7f1f515ef3e0 - rustc_query_impl[d9e05d596e7fb2e4]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d9e05d596e7fb2e4]::query_impl::vtable_entries::dynamic_query::{closure#2}::{closure#0}, rustc_middle[f9db403ed88df217]::query::erase::Erased<[u8; 16usize]>>
  21:     0x7f1f515ef39f - <rustc_query_impl[d9e05d596e7fb2e4]::query_impl::vtable_entries::dynamic_query::{closure#2} as core[32850a7867c2faaf]::ops::function::FnOnce<(rustc_middle[f9db403ed88df217]::ty::context::TyCtxt, rustc_type_ir[db10ef31f899621e]::predicate::TraitRef<rustc_middle[f9db403ed88df217]::ty::context::TyCtxt>)>>::call_once
  22:     0x7f1f515ecfd4 - rustc_query_system[5bf9c757c7651d1c]::query::plumbing::try_execute_query::<rustc_query_impl[d9e05d596e7fb2e4]::DynamicConfig<rustc_query_system[5bf9c757c7651d1c]::query::caches::DefaultCache<rustc_type_ir[db10ef31f899621e]::predicate::TraitRef<rustc_middle[f9db403ed88df217]::ty::context::TyCtxt>, rustc_middle[f9db403ed88df217]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[d9e05d596e7fb2e4]::plumbing::QueryCtxt, false>
  23:     0x7f1f515ecd0f - rustc_query_impl[d9e05d596e7fb2e4]::query_impl::vtable_entries::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7f1f4f0620cd - <rustc_const_eval[c2a8dfe84ccca289]::interpret::eval_context::InterpCx<rustc_const_eval[c2a8dfe84ccca289]::const_eval::machine::CompileTimeMachine>>::vtable_entries
  25:     0x7f1f50ca3b20 - <rustc_const_eval[c2a8dfe84ccca289]::interpret::eval_context::InterpCx<rustc_const_eval[c2a8dfe84ccca289]::const_eval::machine::CompileTimeMachine>>::unsize_into_ptr::<rustc_const_eval[c2a8dfe84ccca289]::interpret::place::PlaceTy>
  26:     0x7f1f50c7cde2 - rustc_const_eval[c2a8dfe84ccca289]::const_eval::eval_queries::eval_body_using_ecx::<rustc_middle[f9db403ed88df217]::mir::interpret::allocation::ConstAllocation>
  27:     0x7f1f5178df8a - rustc_const_eval[c2a8dfe84ccca289]::const_eval::eval_queries::eval_static_initializer_provider
  28:     0x7f1f5178da55 - rustc_query_impl[d9e05d596e7fb2e4]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d9e05d596e7fb2e4]::query_impl::eval_static_initializer::dynamic_query::{closure#2}::{closure#0}, rustc_middle[f9db403ed88df217]::query::erase::Erased<[u8; 16usize]>>
  29:     0x7f1f5178da29 - <rustc_query_impl[d9e05d596e7fb2e4]::query_impl::eval_static_initializer::dynamic_query::{closure#2} as core[32850a7867c2faaf]::ops::function::FnOnce<(rustc_middle[f9db403ed88df217]::ty::context::TyCtxt, rustc_span[56e001752d96add4]::def_id::DefId)>>::call_once
  30:     0x7f1f5088fb5b - rustc_query_system[5bf9c757c7651d1c]::query::plumbing::try_execute_query::<rustc_query_impl[d9e05d596e7fb2e4]::DynamicConfig<rustc_query_system[5bf9c757c7651d1c]::query::caches::DefIdCache<rustc_middle[f9db403ed88df217]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[d9e05d596e7fb2e4]::plumbing::QueryCtxt, false>
  31:     0x7f1f5173737a - rustc_query_impl[d9e05d596e7fb2e4]::query_impl::eval_static_initializer::get_query_non_incr::__rust_end_short_backtrace
  32:     0x7f1f50a443fb - <rustc_middle[f9db403ed88df217]::ty::context::TyCtxt>::par_hir_body_owners::<rustc_hir_analysis[c14eb0767420332]::check_crate::{closure#2}>::{closure#0}
  33:     0x7f1f50a43c44 - rustc_hir_analysis[c14eb0767420332]::check_crate
  34:     0x7f1f5162c09b - rustc_interface[c6a26c9f392246cf]::passes::analysis
  35:     0x7f1f5162bcf5 - rustc_query_impl[d9e05d596e7fb2e4]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d9e05d596e7fb2e4]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[f9db403ed88df217]::query::erase::Erased<[u8; 0usize]>>
  36:     0x7f1f51902963 - rustc_query_system[5bf9c757c7651d1c]::query::plumbing::try_execute_query::<rustc_query_impl[d9e05d596e7fb2e4]::DynamicConfig<rustc_query_system[5bf9c757c7651d1c]::query::caches::SingleCache<rustc_middle[f9db403ed88df217]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[d9e05d596e7fb2e4]::plumbing::QueryCtxt, false>
  37:     0x7f1f5190274e - rustc_query_impl[d9e05d596e7fb2e4]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  38:     0x7f1f51a93111 - <rustc_interface[c6a26c9f392246cf]::passes::create_and_enter_global_ctxt<core[32850a7867c2faaf]::option::Option<rustc_interface[c6a26c9f392246cf]::queries::Linker>, rustc_driver_impl[252c3262fddb99f]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[32850a7867c2faaf]::ops::function::FnOnce<(&rustc_session[eab982bd009dcc5a]::session::Session, rustc_middle[f9db403ed88df217]::ty::context::CurrentGcx, alloc[7a43974b6697a11c]::sync::Arc<rustc_data_structures[721127a3047d6cb5]::jobserver::Proxy>, &std[765ed69a96918746]::sync::once_lock::OnceLock<rustc_middle[f9db403ed88df217]::ty::context::GlobalCtxt>, &rustc_data_structures[721127a3047d6cb5]::sync::worker_local::WorkerLocal<rustc_middle[f9db403ed88df217]::arena::Arena>, &rustc_data_structures[721127a3047d6cb5]::sync::worker_local::WorkerLocal<rustc_hir[41466cadac454391]::Arena>, rustc_driver_impl[252c3262fddb99f]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  39:     0x7f1f518840b4 - rustc_interface[c6a26c9f392246cf]::interface::run_compiler::<(), rustc_driver_impl[252c3262fddb99f]::run_compiler::{closure#0}>::{closure#1}
  40:     0x7f1f5182cb7a - std[765ed69a96918746]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[c6a26c9f392246cf]::util::run_in_thread_with_globals<rustc_interface[c6a26c9f392246cf]::util::run_in_thread_pool_with_globals<rustc_interface[c6a26c9f392246cf]::interface::run_compiler<(), rustc_driver_impl[252c3262fddb99f]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  41:     0x7f1f5182c93e - <std[765ed69a96918746]::thread::lifecycle::spawn_unchecked<rustc_interface[c6a26c9f392246cf]::util::run_in_thread_with_globals<rustc_interface[c6a26c9f392246cf]::util::run_in_thread_pool_with_globals<rustc_interface[c6a26c9f392246cf]::interface::run_compiler<(), rustc_driver_impl[252c3262fddb99f]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[32850a7867c2faaf]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  42:     0x7f1f5182e702 - std::sys::thread::unix::Thread::new::thread_start::h982f9ea829d1b5fb
  43:     0x7f1f4b4aa609 - start_thread
                               at /build/glibc-B3wQXB/glibc-2.31/nptl/pthread_create.c:477:8
  44:     0x7f1f4b3cf353 - clone
                               at /build/glibc-B3wQXB/glibc-2.31/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:95:0
  45:                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 1.94.0 (4a4ef493e 2026-03-02) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [vtable_entries] finding all vtable entries for trait `Bar`
#1 [eval_static_initializer] evaluating initializer of static `BAR`
... and 1 other queries... use `env RUST_BACKTRACE=1` to see the full query stack
error: aborting due to 3 previous errors; 3 warnings emitted