rustc miscompiled on powerpc64 after LLVM 22 update

[tgross35]

Code

I don't have the ability to reproduce but this comes from a cargo install cargo-nextest on PPC64le, building gimli.

Happened with this CI run: https://github.com/rust-lang/compiler-builtins/actions/runs/21465837588/job/61827742076?pr=1064

Meta

Version:

rustc 1.95.0-nightly (de6d33c03 2026-01-28) running on powerpc64le-unknown-linux-gnu

Error output

Abridged backtrace:

thread 'rustc' (3443) panicked at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/core/src/slice/sort/shared/smallsort.rs:860:5:
user-provided comparison function does not correctly implement a total order
stack backtrace:
...
  26:     0x7fff865fd080 - core[f32139a12fc3802d]::slice::sort::stable::driftsort_main::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt, alloc[1978f500b81eda50]::vec::Vec<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect>>
  27:     0x7fff86515ba0 - <rustc_mir_transform[88d55b52b8bab073]::jump_threading::JumpThreading as rustc_mir_transform[88d55b52b8bab073]::pass_manager::MirPass>::run_pass
  28:     0x7fff864dc5e8 - rustc_mir_transform[88d55b52b8bab073]::pass_manager::run_passes_inner
  29:     0x7fff8657ea0c - rustc_mir_transform[88d55b52b8bab073]::run_optimization_passes
  30:     0x7fff8657dc28 - rustc_mir_transform[88d55b52b8bab073]::optimized_mir
  31:     0x7fff87f424f8 - rustc_query_impl[2941d06d8315d6e5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2941d06d8315d6e5]::query_impl::optimized_mir::make_query_vtable::{closure#2}::{closure#0}, rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 8usize]>>
...
[04](https://github.com/rust-lang/compiler-builtins/actions/runs/21465837588/job/61827742076?pr=1064#step:7:707)
note: rustc 1.95.0-nightly (de6d33c03 2026-01-28) running on powerpc64le-unknown-linux-gnu

note: compiler flags: --crate-type lib -C opt-level=3 -C embed-bitcode=no -C strip=debuginfo

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

query stack during panic:
#0 [optimized_mir] optimizing MIR for `read::value::<impl at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gimli-0.31.1/src/read/value.rs:152:1: 152:11>::rem`
#1 [cross_crate_inlinable] whether the item should be made inlinable across crates
#2 [reachable_set] reachability
end of query stack
error: could not compile `gimli` (lib)

Caused by:
  process didn't exit successfully: `/home/runner/.rustup/toolchains/nightly-powerpc64le-unknown-linux-gnu/bin/rustc --crate-name gimli --edition=2018 /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gimli-0.31.1/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -C embed-bitcode=no --cfg 'feature="read"' --cfg 'feature="read-core"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("default", "endian-reader", "fallible-iterator", "read", "read-all", "read-core", "rustc-dep-of-std", "std", "write"))' -C metadata=3754b661b61fe6f7 -C extra-filename=-8b85df64c0e5fd7a --out-dir /tmp/cargo-installvGZBpH/release/deps -C strip=debuginfo -L dependency=/tmp/cargo-installvGZBpH/release/deps --cap-lints allow -Dwarnings` (exit status: 101)

Backtrace

thread 'rustc' (3443) panicked at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/core/src/slice/sort/shared/smallsort.rs:860:5:
user-provided comparison function does not correctly implement a total order
stack backtrace:
   0:     0x7fff89f12760 - std[d497cf1afc50e215]::backtrace_rs::backtrace::libunwind::trace
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9
   1:     0x7fff89f12760 - std[d497cf1afc50e215]::backtrace_rs::backtrace::trace_unsynchronized::<std[d497cf1afc50e215]::sys::backtrace::_print_fmt::{closure#1}>
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14
   2:     0x7fff89f12760 - std[d497cf1afc50e215]::sys::backtrace::_print_fmt
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/sys/backtrace.rs:74:9
   3:     0x7fff89f12760 - <<std[d497cf1afc50e215]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[f32139a12fc3802d]::fmt::Display>::fmt
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/sys/backtrace.rs:44:26
   4:     0x7fff89f6ead8 - <core[f32139a12fc3802d]::fmt::rt::Argument>::fmt
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/core/src/fmt/rt.rs:152:76
   5:     0x7fff89f6ead8 - core[f32139a12fc3802d]::fmt::write
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/core/src/fmt/mod.rs:1686:22
   6:     0x7fff89f2f160 - std[d497cf1afc50e215]::io::default_write_fmt::<std[d497cf1afc50e215]::sys::stdio::unix::Stderr>
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/io/mod.rs:639:11
   7:     0x7fff89f2f160 - <std[d497cf1afc50e215]::sys::stdio::unix::Stderr as std[d497cf1afc50e215]::io::Write>::write_fmt
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/io/mod.rs:1994:13
   8:     0x7fff89ed8d30 - <std[d497cf1afc50e215]::sys::backtrace::BacktraceLock>::print
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/sys/backtrace.rs:47:9
   9:     0x7fff89ed8d30 - std[d497cf1afc50e215]::panicking::default_hook::{closure#0}
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/panicking.rs:292:27
  10:     0x7fff89f00d38 - std[d497cf1afc50e215]::panicking::default_hook
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/panicking.rs:319:9
  11:     0x7fff7fef701c - <std[d497cf1afc50e215]::panicking::default_hook as core[f32139a12fc3802d]::ops::function::Fn<(&std[d497cf1afc50e215]::panic::PanicHookInfo,)>>::call
  12:     0x7fff7fee3a08 - std[d497cf1afc50e215]::panicking::update_hook::<alloc[1978f500b81eda50]::boxed::Box<rustc_driver_impl[4285e1722225a967]::install_ice_hook::{closure#1}>>::{closure#0}
  13:     0x7fff89f01084 - <alloc[1978f500b81eda50]::boxed::Box<dyn for<'a, 'b> core[f32139a12fc3802d]::ops::function::Fn<(&'a std[d497cf1afc50e215]::panic::PanicHookInfo<'b>,), Output = ()> + core[f32139a12fc3802d]::marker::Send + core[f32139a12fc3802d]::marker::Sync> as core[f32139a12fc3802d]::ops::function::Fn<(&std[d497cf1afc50e215]::panic::PanicHookInfo,)>>::call
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/alloc/src/boxed.rs:2220:9
  14:     0x7fff89f01084 - std[d497cf1afc50e215]::panicking::panic_with_hook
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/panicking.rs:833:13
  15:     0x7fff89ed8e90 - std[d497cf1afc50e215]::panicking::panic_handler::{closure#0}
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/panicking.rs:691:13
  16:     0x7fff89eccb90 - std[d497cf1afc50e215]::sys::backtrace::__rust_end_short_backtrace::<std[d497cf1afc50e215]::panicking::panic_handler::{closure#0}, !>
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/sys/backtrace.rs:182:18
  17:     0x7fff89edb0a4 - __rustc[ae9b106f2a976235]::rust_begin_unwind
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/panicking.rs:689:5
  18:     0x7fff7fd2ac30 - core[f32139a12fc3802d]::panicking::panic_fmt
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/core/src/panicking.rs:80:14
  19:     0x7fff7fd2b824 - core[f32139a12fc3802d]::slice::sort::shared::smallsort::panic_on_ord_violation
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/core/src/slice/sort/shared/smallsort.rs:860:5
  20:     0x7fff864d2610 - core[f32139a12fc3802d]::slice::sort::shared::smallsort::bidirectional_merge::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt>
  21:     0x7fff864d50fc - core[f32139a12fc3802d]::slice::sort::shared::smallsort::small_sort_general_with_scratch::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt>
  22:     0x7fff86506af8 - core[f32139a12fc3802d]::slice::sort::stable::quicksort::quicksort::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt>
  23:     0x7fff8650745c - core[f32139a12fc3802d]::slice::sort::stable::quicksort::quicksort::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt>
  24:     0x7fff8650745c - core[f32139a12fc3802d]::slice::sort::stable::quicksort::quicksort::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt>
  25:     0x7fff86500cec - core[f32139a12fc3802d]::slice::sort::stable::drift::sort::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt>
  26:     0x7fff865fd080 - core[f32139a12fc3802d]::slice::sort::stable::driftsort_main::<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect, <rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect as core[f32139a12fc3802d]::cmp::PartialOrd>::lt, alloc[1978f500b81eda50]::vec::Vec<rustc_mir_transform[88d55b52b8bab073]::jump_threading::EdgeEffect>>
  27:     0x7fff86515ba0 - <rustc_mir_transform[88d55b52b8bab073]::jump_threading::JumpThreading as rustc_mir_transform[88d55b52b8bab073]::pass_manager::MirPass>::run_pass
  28:     0x7fff864dc5e8 - rustc_mir_transform[88d55b52b8bab073]::pass_manager::run_passes_inner
  29:     0x7fff8657ea0c - rustc_mir_transform[88d55b52b8bab073]::run_optimization_passes
  30:     0x7fff8657dc28 - rustc_mir_transform[88d55b52b8bab073]::optimized_mir
  31:     0x7fff87f424f8 - rustc_query_impl[2941d06d8315d6e5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2941d06d8315d6e5]::query_impl::optimized_mir::make_query_vtable::{closure#2}::{closure#0}, rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 8usize]>>
  32:     0x7fff88028b0c - <rustc_query_impl[2941d06d8315d6e5]::query_impl::optimized_mir::make_query_vtable::{closure#2} as core[f32139a12fc3802d]::ops::function::FnOnce<(rustc_middle[a3a65ffa40cd2cc0]::ty::context::TyCtxt, rustc_span[1d04537fca491d49]::def_id::DefId)>>::call_once
  33:     0x7fff87e7bce8 - rustc_query_system[7bd5e190329241fa]::query::plumbing::try_execute_query::<rustc_query_impl[2941d06d8315d6e5]::SemiDynamicQueryDispatcher<rustc_query_system[7bd5e190329241fa]::query::caches::DefIdCache<rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[2941d06d8315d6e5]::plumbing::QueryCtxt, false>
  34:     0x7fff8823f55c - rustc_query_impl[2941d06d8315d6e5]::query_impl::optimized_mir::get_query_non_incr::__rust_end_short_backtrace
  35:     0x7fff866a76fc - rustc_mir_transform[88d55b52b8bab073]::cross_crate_inline::cross_crate_inlinable
  36:     0x7fff87f48fac - rustc_query_impl[2941d06d8315d6e5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2941d06d8315d6e5]::query_impl::cross_crate_inlinable::make_query_vtable::{closure#2}::{closure#0}, rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 1usize]>>
  37:     0x7fff88047a5c - <rustc_query_impl[2941d06d8315d6e5]::query_impl::cross_crate_inlinable::make_query_vtable::{closure#2} as core[f32139a12fc3802d]::ops::function::FnOnce<(rustc_middle[a3a65ffa40cd2cc0]::ty::context::TyCtxt, rustc_span[1d04537fca491d49]::def_id::DefId)>>::call_once
  38:     0x7fff87e71028 - rustc_query_system[7bd5e190329241fa]::query::plumbing::try_execute_query::<rustc_query_impl[2941d06d8315d6e5]::SemiDynamicQueryDispatcher<rustc_query_system[7bd5e190329241fa]::query::caches::DefIdCache<rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[2941d06d8315d6e5]::plumbing::QueryCtxt, false>
  39:     0x7fff88151598 - rustc_query_impl[2941d06d8315d6e5]::query_impl::cross_crate_inlinable::get_query_non_incr::__rust_end_short_backtrace
  40:     0x7fff877a1fa8 - rustc_passes[d50831950448d6dd]::reachable::recursively_reachable
  41:     0x7fff877a0ffc - rustc_passes[d50831950448d6dd]::reachable::reachable_set
  42:     0x7fff87f42628 - rustc_query_impl[2941d06d8315d6e5]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2941d06d8315d6e5]::query_impl::reachable_set::make_query_vtable::{closure#2}::{closure#0}, rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 8usize]>>
  43:     0x7fff880291c4 - <rustc_query_impl[2941d06d8315d6e5]::query_impl::reachable_set::make_query_vtable::{closure#2} as core[f32139a12fc3802d]::ops::function::FnOnce<(rustc_middle[a3a65ffa40cd2cc0]::ty::context::TyCtxt, ())>>::call_once
  44:     0x7fff87e8933c - rustc_query_system[7bd5e190329241fa]::query::plumbing::try_execute_query::<rustc_query_impl[2941d06d8315d6e5]::SemiDynamicQueryDispatcher<rustc_query_system[7bd5e190329241fa]::query::caches::SingleCache<rustc_middle[a3a65ffa40cd2cc0]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[2941d06d8315d6e5]::plumbing::QueryCtxt, false>
  45:     0x7fff88182b1c - rustc_query_impl[2941d06d8315d6e5]::query_impl::reachable_set::get_query_non_incr::__rust_end_short_backtrace
  46:     0x7fff88c019f8 - <rustc_metadata[cc6d3afd4af3b0b6]::rmeta::encoder::EncodeContext>::encode_crate_root
  47:     0x7fff7fc7aa20 - rustc_metadata[cc6d3afd4af3b0b6]::rmeta::encoder::encode_metadata::{closure#3}::{closure#0}
  48:     0x7fff88c19f54 - <rustc_metadata[cc6d3afd4af3b0b6]::rmeta::encoder::encode_metadata::{closure#3} as core[f32139a12fc3802d]::ops::function::FnOnce<(rustc_middle[a3a65ffa40cd2cc0]::ty::context::TyCtxt, &std[d497cf1afc50e215]::path::Path)>>::call_once
  49:     0x7fff88c14e70 - rustc_metadata[cc6d3afd4af3b0b6]::rmeta::encoder::encode_metadata
  50:     0x7fff88cb79dc - rustc_metadata[cc6d3afd4af3b0b6]::fs::encode_and_write_metadata
  51:     0x7fff8029b6c8 - <rustc_interface[d8e866169733720b]::queries::Linker>::codegen_and_build_linker
  52:     0x7fff7ff15ba8 - <std[d497cf1afc50e215]::thread::local::LocalKey<core[f32139a12fc3802d]::cell::Cell<*const ()>>>::with::<rustc_middle[a3a65ffa40cd2cc0]::ty::context::tls::enter_context<<rustc_middle[a3a65ffa40cd2cc0]::ty::context::GlobalCtxt>::enter<rustc_interface[d8e866169733720b]::passes::create_and_enter_global_ctxt<core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>, rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>>::{closure#1}, core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>>::{closure#0}, core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>>
  53:     0x7fff7ff24490 - <rustc_middle[a3a65ffa40cd2cc0]::ty::context::TyCtxt>::create_global_ctxt::<core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>, rustc_interface[d8e866169733720b]::passes::create_and_enter_global_ctxt<core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>, rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}>
  54:     0x7fff7ff1226c - <rustc_interface[d8e866169733720b]::passes::create_and_enter_global_ctxt<core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>, rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[f32139a12fc3802d]::ops::function::FnOnce<(&rustc_session[c8d5d82282de2060]::session::Session, rustc_middle[a3a65ffa40cd2cc0]::ty::context::CurrentGcx, alloc[1978f500b81eda50]::sync::Arc<rustc_data_structures[dc0b461227d06ae8]::jobserver::Proxy>, &std[d497cf1afc50e215]::sync::once_lock::OnceLock<rustc_middle[a3a65ffa40cd2cc0]::ty::context::GlobalCtxt>, &rustc_data_structures[dc0b461227d06ae8]::sync::worker_local::WorkerLocal<rustc_middle[a3a65ffa40cd2cc0]::arena::Arena>, &rustc_data_structures[dc0b461227d06ae8]::sync::worker_local::WorkerLocal<rustc_hir[2b2bed73c9d82790]::Arena>, rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  55:     0x7fff7fef7a04 - rustc_interface[d8e866169733720b]::passes::create_and_enter_global_ctxt::<core[f32139a12fc3802d]::option::Option<rustc_interface[d8e866169733720b]::queries::Linker>, rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}::{closure#2}>
  56:     0x7fff7ff9b47c - <scoped_tls[50579219e8d96422]::ScopedKey<rustc_span[1d04537fca491d49]::SessionGlobals>>::set::<rustc_interface[d8e866169733720b]::util::run_in_thread_with_globals<rustc_interface[d8e866169733720b]::util::run_in_thread_pool_with_globals<rustc_interface[d8e866169733720b]::interface::run_compiler<(), rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  57:     0x7fff7ff154ac - rustc_span[1d04537fca491d49]::create_session_globals_then::<(), rustc_interface[d8e866169733720b]::util::run_in_thread_with_globals<rustc_interface[d8e866169733720b]::util::run_in_thread_pool_with_globals<rustc_interface[d8e866169733720b]::interface::run_compiler<(), rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
  58:     0x7fff7ff8dcd4 - std[d497cf1afc50e215]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[d8e866169733720b]::util::run_in_thread_with_globals<rustc_interface[d8e866169733720b]::util::run_in_thread_pool_with_globals<rustc_interface[d8e866169733720b]::interface::run_compiler<(), rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  59:     0x7fff7ff92060 - <std[d497cf1afc50e215]::thread::lifecycle::spawn_unchecked<rustc_interface[d8e866169733720b]::util::run_in_thread_with_globals<rustc_interface[d8e866169733720b]::util::run_in_thread_pool_with_globals<rustc_interface[d8e866169733720b]::interface::run_compiler<(), rustc_driver_impl[4285e1722225a967]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[f32139a12fc3802d]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  60:     0x7fff89f0eb8c - <alloc[1978f500b81eda50]::boxed::Box<dyn core[f32139a12fc3802d]::ops::function::FnOnce<(), Output = ()> + core[f32139a12fc3802d]::marker::Send> as core[f32139a12fc3802d]::ops::function::FnOnce<()>>::call_once
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/alloc/src/boxed.rs:2206:9
  61:     0x7fff89f0eb8c - <std[d497cf1afc50e215]::sys::thread::unix::Thread>::new::thread_start
                               at /rustc/de6d33c033441c5880b863f94d7a3ec8cad141bd/library/std/src/sys/thread/unix.rs:127:17
  62:     0x7fff8f4d2a9c - <unknown>
  63:     0x7fff8f5885fc - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

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

note: please attach the file at `/home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gimli-0.31.1/rustc-ice-2026-01-29T04_39_56-3440.txt` to your bug report

note: rustc 1.95.0-nightly (de6d33c03 2026-01-28) running on powerpc64le-unknown-linux-gnu

note: compiler flags: --crate-type lib -C opt-level=3 -C embed-bitcode=no -C strip=debuginfo

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

query stack during panic:
#0 [optimized_mir] optimizing MIR for `read::value::<impl at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gimli-0.31.1/src/read/value.rs:152:1: 152:11>::rem`
#1 [cross_crate_inlinable] whether the item should be made inlinable across crates
#2 [reachable_set] reachability
end of query stack
error: could not compile `gimli` (lib)

Caused by:
  process didn't exit successfully: `/home/runner/.rustup/toolchains/nightly-powerpc64le-unknown-linux-gnu/bin/rustc --crate-name gimli --edition=2018 /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gimli-0.31.1/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -C embed-bitcode=no --cfg 'feature="read"' --cfg 'feature="read-core"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("default", "endian-reader", "fallible-iterator", "read", "read-all", "read-core", "rustc-dep-of-std", "std", "write"))' -C metadata=3754b661b61fe6f7 -C extra-filename=-8b85df64c0e5fd7a --out-dir /tmp/cargo-installvGZBpH/release/deps -C strip=debuginfo -L dependency=/tmp/cargo-installvGZBpH/release/deps --cap-lints allow -Dwarnings` (exit status: 101)
warning: build failed, waiting for other jobs to finish...
error: failed to compile `cargo-nextest v0.9.124`, intermediate artifacts can be found at `/tmp/cargo-installvGZBpH`.
To reuse those artifacts with a future compilation, set the environment variable `CARGO_TARGET_DIR` to that path.

[tgross35]

Labeling ppc since it showed up there and not on the other platform using cargo-install (s390x), but I expect this is due to code that is only cfg-enabled on ppc.

Cc @Gelbpunkt in case you have a system handy to see if you can reproduce.

[tgross35]

Attempted to repro on an x86 host by checking out giml 0.31.1 (the relevant version) and running:

rustc --crate-name gimli --edition=2018 src/lib.rs --crate-type lib --emit=dep-info,metadata,link -Copt-level=3 -Cembed-bitcode=no --cfg 'feature="read"' --cfg 'feature="read-core"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("default", "endian-reader", "fallible-iterator", "read", "read-all", "read-core", "rustc-dep-of-std", "std", "write"))' -C metadata=3754b661b61fe6f7 -C extra-filename=-8b85df64c0e5fd7a --target powerpc64le-unknown-linux-gnu

But no luck.

[Gelbpunkt]

I can reproduce on Fedora 43 with rustc 1.95.0-nightly (de6d33c03 2026-01-28) running on powerpc64le-unknown-linux-gnu, first try to install cargo-nextest triggers the ICE.

I'll try to bisect.

[tgross35]

Thanks for the instant response. Would mind trying to build https://github.com/gimli-rs/gimli/releases/tag/0.31.1 in release mode? I'm wondering whether I couldn't repro on x86 because it needs the whole cargo install, or if there's some host-specific behavior here.

That would be kind of surprising unless something happened with the LLVM upgrade.

[Gelbpunkt]

Thanks for the instant response. Would mind trying to build https://github.com/gimli-rs/gimli/releases/tag/0.31.1 in release mode? I'm wondering whether I couldn't repro on x86 because it needs the whole cargo install, or if there's some host-specific behavior here.

That would be kind of surprising unless something happened with the LLVM upgrade.

I can reproduce with just your rustc invocation building 0.31.1 or with cargo check --features read,read-core --release (without --release it works).