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C-bugCategory: This is a bug.Category: This is a bug.I-ICEIssue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.Relevant to the compiler team, which will review and decide on the PR/issue.
Description
Code
fn main() {
let _: &mut (dyn ?Sized + !Send) = &mut {};
}Meta
rustc --version --verbose:
rustc 1.91.0-nightly (9c27f27ea 2025-09-08)
binary: rustc
commit-hash: 9c27f27ea3bab79a2fec827ef3ae0009959d60f4
commit-date: 2025-09-08
host: x86_64-unknown-linux-gnu
release: 1.91.0-nightly
LLVM version: 21.1.0
Error output
error: negative bounds are not supported
--> test.fuzz:2:31
|
2 | let _: &mut (dyn ?Sized + !Send) = &mut {};
| ^
error: relaxed bounds are not permitted in trait object types
--> test.fuzz:2:22
|
2 | let _: &mut (dyn ?Sized + !Send) = &mut {};
| ^^^^^^
thread 'rustc' (388594) panicked at compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs:385:17:
assertion `left == right` failed
left: Negative
right: Positive
Backtrace
stack backtrace:
0: 0x7f04913afec3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hf30880b118ce69a7
1: 0x7f0491a01bd8 - core::fmt::write::h2adee94c9530c769
2: 0x7f0491364cf1 - std::io::Write::write_fmt::hf9fd682cd305994d
3: 0x7f0491375e12 - std::sys::backtrace::BacktraceLock::print::h2e8eaa47e6244167
4: 0x7f049137bd59 - std::panicking::default_hook::{{closure}}::hce66ca19674736b6
5: 0x7f049137b883 - std::panicking::default_hook::h378eb22e7f245ba6
6: 0x7f04903c3707 - std[60f4c921464387a8]::panicking::update_hook::<alloc[af66c0f7f367d3a4]::boxed::Box<rustc_driver_impl[6e5208ea2b150886]::install_ice_hook::{closure#1}>>::{closure#0}
7: 0x7f049137c17f - std::panicking::panic_with_hook::h107561c887d41fb4
8: 0x7f049137bf3a - std::panicking::panic_handler::{{closure}}::h22ca1e42f3e34cf3
9: 0x7f0491375f49 - std::sys::backtrace::__rust_end_short_backtrace::h2a269d3827952e51
10: 0x7f049135672d - __rustc[46dfa2e28c3cccbc]::rust_begin_unwind
11: 0x7f048dabf8f0 - core::panicking::panic_fmt::hb26515e908d4a63d
12: 0x7f048fdbbb03 - core::panicking::assert_failed_inner::h54b5c33d4b117389
13: 0x7f04910fa013 - core[494a681d6e07a62e]::panicking::assert_failed::<rustc_type_ir[539e53880383513c]::predicate::PredicatePolarity, rustc_type_ir[539e53880383513c]::predicate::PredicatePolarity>
14: 0x7f0492877393 - <dyn rustc_hir_analysis[84a042027edab4a]::hir_ty_lowering::HirTyLowerer>::lower_trait_object_ty::{closure#0}
15: 0x7f049243b967 - <dyn rustc_hir_analysis[84a042027edab4a]::hir_ty_lowering::HirTyLowerer>::lower_ty::{closure#0}
16: 0x7f049243acca - <dyn rustc_hir_analysis[84a042027edab4a]::hir_ty_lowering::HirTyLowerer>::lower_ty::{closure#0}
17: 0x7f0492008fde - <rustc_hir_typeck[4caaa11dff9d1644]::gather_locals::GatherLocalsVisitor>::declare
18: 0x7f0492005128 - <rustc_hir_typeck[4caaa11dff9d1644]::fn_ctxt::FnCtxt>::check_expr_block
19: 0x7f04920878fb - <rustc_hir_typeck[4caaa11dff9d1644]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
20: 0x7f0492010718 - rustc_hir_typeck[4caaa11dff9d1644]::check::check_fn
21: 0x7f0491f14044 - rustc_hir_typeck[4caaa11dff9d1644]::typeck_with_inspect::{closure#0}
22: 0x7f0491f12836 - rustc_query_impl[d503ea7333d9f192]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d503ea7333d9f192]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[62f76fb1ad15f043]::query::erase::Erased<[u8; 8usize]>>
23: 0x7f0491c2f345 - rustc_query_system[36926af04fc30fbf]::query::plumbing::try_execute_query::<rustc_query_impl[d503ea7333d9f192]::DynamicConfig<rustc_data_structures[d45417cb7c5e80c2]::vec_cache::VecCache<rustc_span[84d5e499882068e4]::def_id::LocalDefId, rustc_middle[62f76fb1ad15f043]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[36926af04fc30fbf]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[d503ea7333d9f192]::plumbing::QueryCtxt, false>
24: 0x7f0491c2ed89 - rustc_query_impl[d503ea7333d9f192]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
25: 0x7f0491c3aab1 - rustc_hir_analysis[84a042027edab4a]::check_crate
26: 0x7f0491c272f0 - rustc_interface[f234d5aad18497a0]::passes::analysis
27: 0x7f0491c26fa1 - rustc_query_impl[d503ea7333d9f192]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[d503ea7333d9f192]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[62f76fb1ad15f043]::query::erase::Erased<[u8; 0usize]>>
28: 0x7f0492a0f526 - rustc_query_system[36926af04fc30fbf]::query::plumbing::try_execute_query::<rustc_query_impl[d503ea7333d9f192]::DynamicConfig<rustc_query_system[36926af04fc30fbf]::query::caches::SingleCache<rustc_middle[62f76fb1ad15f043]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[d503ea7333d9f192]::plumbing::QueryCtxt, false>
29: 0x7f0492a0f17c - rustc_query_impl[d503ea7333d9f192]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
30: 0x7f0492cd35a4 - rustc_interface[f234d5aad18497a0]::passes::create_and_enter_global_ctxt::<core[494a681d6e07a62e]::option::Option<rustc_interface[f234d5aad18497a0]::queries::Linker>, rustc_driver_impl[6e5208ea2b150886]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
31: 0x7f0492c734be - rustc_interface[f234d5aad18497a0]::interface::run_compiler::<(), rustc_driver_impl[6e5208ea2b150886]::run_compiler::{closure#0}>::{closure#1}
32: 0x7f0492bb3c78 - std[60f4c921464387a8]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[f234d5aad18497a0]::util::run_in_thread_with_globals<rustc_interface[f234d5aad18497a0]::util::run_in_thread_pool_with_globals<rustc_interface[f234d5aad18497a0]::interface::run_compiler<(), rustc_driver_impl[6e5208ea2b150886]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
33: 0x7f0492bb395c - <<std[60f4c921464387a8]::thread::Builder>::spawn_unchecked_<rustc_interface[f234d5aad18497a0]::util::run_in_thread_with_globals<rustc_interface[f234d5aad18497a0]::util::run_in_thread_pool_with_globals<rustc_interface[f234d5aad18497a0]::interface::run_compiler<(), rustc_driver_impl[6e5208ea2b150886]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[494a681d6e07a62e]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
34: 0x7f0492bb9e8d - std::sys::pal::unix::thread::Thread::new::thread_start::h0ed16f40fa4b751a
35: 0x7f048c66bac3 - start_thread
at ./nptl/pthread_create.c:442:8
36: 0x7f048c6fd850 - __GI___clone3
at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81:0
37: 0x0 - <unknown>
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Labels
C-bugCategory: This is a bug.Category: This is a bug.I-ICEIssue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.Relevant to the compiler team, which will review and decide on the PR/issue.
Activity
fmease commentedon Sep 9, 2025
Thanks for your report! Please try to look for duplicates first. Dupe of #144241.
dyn !Sized#144241brutalsavage commentedon Sep 9, 2025
Thanks for the check, sorry I had previously seen the issue you pointed out but saw the error line was slightly different in this one, will check more carefully.