ICE - unsafe precondition violation in slice::from_raw_parts_mut on powerpc64-unknown-linux-musl

[Gelbpunkt]

Code

Pretty much any Rust code that isn't an empty fn main() {}. For example, tests/ui/traits/map-types.rs:

use std::collections::HashMap;



trait Map<K, V>
{
    fn get(&self, k: K) -> V { panic!() }
}

impl<K, V> Map<K, V> for HashMap<K, V> {}

// Test that trait types printed in error msgs include the type arguments.

fn main() {
    let x: Box<HashMap<isize, isize>> = HashMap::new().into();
    let x: Box<dyn Map<isize, isize>> = x;
    let y: Box<dyn Map<usize, isize>> = Box::new(x);
    //~^ ERROR `Box<dyn Map<isize, isize>>: Map<usize, isize>` is not satisfied
}

Meta

rustc --version --verbose:

rustc 1.89.0-dev
binary: rustc
commit-hash: unknown
commit-date: unknown
host: powerpc64-unknown-linux-musl
release: 1.89.0-dev
LLVM version: 20.1.5

Error output

thread 'rustc' panicked at /usr/lib/rustlib/src/rust/library/core/src/panicking.rs:226:5:
unsafe precondition(s) violated: slice::from_raw_parts_mut requires the pointer to be aligned and non-null, and the total size of the slice not to exceed `isize::MAX`

This indicates a bug in the program. This Undefined Behavior check is optional, and cannot be relied on for safety.

Backtrace

stack backtrace:
   0:     0x3998da863028 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h6b7a16c5580db569
   1:     0x3998da8c49e8 - core::fmt::write::h412196edc8a0bac6
   2:     0x3998da852710 - std::io::Write::write_fmt::h601d56a19420a788
   3:     0x3998da862ea0 - std::sys::backtrace::BacktraceLock::print::h17bff0d3f977264e
   4:     0x3998da867bf8 - std::panicking::default_hook::{{closure}}::ha5fc841ae5cd04eb
   5:     0x3998da867884 - std::panicking::default_hook::h87486f900b0501f7
   6:     0x3998d58bedfc - <std[907ab836018c748a]::panicking::default_hook as core[a1430d4ba98a45c9]::ops::function::Fn<(&std[907ab836018c748a]::panic::PanicHookInfo,)>>::call
                               at /usr/lib/rustlib/src/rust/library/core/src/ops/function.rs:79:5
   7:     0x3998d58d363c - <alloc[8a3938205d7c8a1c]::boxed::Box<dyn for<'a, 'b> core[a1430d4ba98a45c9]::ops::function::Fn<(&'a std[907ab836018c748a]::panic::PanicHookInfo<'b>,), Output = ()> + core[a1430d4ba98a45c9]::marker::Send + core[a1430d4ba98a45c9]::marker::Sync> as core[a1430d4ba98a45c9]::ops::function::Fn<(&std[907ab836018c748a]::panic::PanicHookInfo,)>>::call
                               at /usr/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1980:9
   8:     0x3998d58d372c - {closure#1}
                               at /home/adrian/rust/compiler/rustc_driver_impl/src/lib.rs:1362:17
   9:     0x3998d58d372c - call<(&(dyn core::ops::function::Fn<(&std::panic::PanicHookInfo), Output=()> + core::marker::Send + core::marker::Sync), &std::panic::PanicHookInfo), rustc_driver_impl::install_ice_hook::{closure_env#1}, alloc::alloc::Global>
                               at /usr/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1980:9
  10:     0x3998d58bebcc - std[907ab836018c748a]::panicking::update_hook::<alloc[8a3938205d7c8a1c]::boxed::Box<rustc_driver_impl[3cb4f2869d0b6653]::install_ice_hook::{closure#1}>>::{closure#0}
                               at /usr/lib/rustlib/src/rust/library/std/src/panicking.rs:243:47
  11:     0x3998da868d38 - std::panicking::rust_panic_with_hook::h01dad58d372d72b9
  12:     0x3998da86875c - std::panicking::begin_panic_handler::{{closure}}::h0921d5db50e2f3db
  13:     0x3998da8636dc - std::sys::backtrace::__rust_end_short_backtrace::h2a52412d337f6395
  14:     0x3998da868200 - __rustc[820ce06c06146c08]::rust_begin_unwind
  15:     0x3998da8bf4e4 - core::panicking::panic_nounwind_fmt::hea1385ba292cdf61
  16:     0x3998da8bf5c4 - core::panicking::panic_nounwind::h910baf6dda7e5e34
  17:     0x3998da6aee7c - precondition_check
                               at /usr/lib/rustlib/src/rust/library/core/src/ub_checks.rs:68:21
  18:     0x3998da6aee7c - from_raw_parts_mut<alloc::boxed::Box<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>, alloc::alloc::Global>>
                               at /usr/lib/rustlib/src/rust/library/core/src/ub_checks.rs:75:17
  19:     0x3998da6aee7c - as_mut_slice<alloc::boxed::Box<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>, alloc::alloc::Global>>
                               at /home/adrian/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/thin-vec-0.2.14/src/lib.rs:1047:18
  20:     0x3998da6aee7c - deref_mut<alloc::boxed::Box<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>, alloc::alloc::Global>>
                               at /home/adrian/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/thin-vec-0.2.14/src/lib.rs:1711:9
  21:     0x3998da6aee7c - drop_non_singleton<alloc::boxed::Box<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>, alloc::alloc::Global>>
                               at /home/adrian/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/thin-vec-0.2.14/src/lib.rs:1684:41
  22:     0x3998d588c7cc - drop<alloc::boxed::Box<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>, alloc::alloc::Global>>
                               at /home/adrian/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/thin-vec-0.2.14/src/lib.rs:1696:13
  23:     0x3998d588c7cc - drop_in_place<thin_vec::ThinVec<alloc::boxed::Box<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>, alloc::alloc::Global>>>
                               at /usr/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:524:1
  24:     0x3998d588c7cc - drop_in_place<rustc_ast::ast::Crate>
                               at /usr/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:524:1
  25:     0x3998d58c5d80 - drop_in_place<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
                               at /usr/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:524:1
  26:     0x3998d58c5060 - enter<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
                               at /home/adrian/rust/compiler/rustc_middle/src/ty/context.rs:1497:5
  27:     0x3998d58c5060 - create_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
                               at /home/adrian/rust/compiler/rustc_middle/src/ty/context.rs:1717:9
  28:     0x3998d581aaf4 - {closure#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
                               at /home/adrian/rust/compiler/rustc_interface/src/passes.rs:873:9
  29:     0x3998d581aaf4 - call_once<rustc_interface::passes::create_and_enter_global_ctxt::{closure_env#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, (&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2})>
                               at /usr/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  30:     0x3998d58d2f90 - call_once<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), dyn core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), Output=core::option::Option<rustc_interface::queries::Linker>>, alloc::alloc::Global>
                               at /usr/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1966:9
  31:     0x3998d58195f4 - create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
                               at /home/adrian/rust/compiler/rustc_interface/src/passes.rs:914:5
  32:     0x3998d581896c - {closure#0}
                               at /home/adrian/rust/compiler/rustc_driver_impl/src/lib.rs:338:22
  33:     0x3998d581896c - {closure#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
                               at /home/adrian/rust/compiler/rustc_interface/src/interface.rs:526:80
  34:     0x3998d581896c - call_once<(), rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>
                               at /usr/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9
  35:     0x3998d581896c - do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/panicking.rs:589:40
  36:     0x3998d581896c - try<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>>
                               at /usr/lib/rustlib/src/rust/library/std/src/panicking.rs:552:19
  37:     0x3998d581896c - catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/panic.rs:359:14
  38:     0x3998d5815778 - {closure#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
                               at /home/adrian/rust/compiler/rustc_interface/src/interface.rs:526:23
  39:     0x3998d5815778 - {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>
                               at /home/adrian/rust/compiler/rustc_interface/src/util.rs:199:17
  40:     0x3998d5815778 - {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
                               at /home/adrian/rust/compiler/rustc_interface/src/util.rs:153:24
  41:     0x3998d5815778 - set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
                               at /home/adrian/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/scoped-tls-1.0.1/src/lib.rs:137:9
  42:     0x3998d58fe9a4 - create_session_globals_then<(), rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>>
                               at /home/adrian/rust/compiler/rustc_span/src/lib.rs:144:5
  43:     0x3998d58f5b10 - {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
                               at /home/adrian/rust/compiler/rustc_interface/src/util.rs:149:17
  44:     0x3998d58f5b10 - __rust_begin_short_backtrace<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:152:18
  45:     0x3998d58f4cc0 - {closure#0}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/thread/mod.rs:559:17
  46:     0x3998d58f4cc0 - call_once<(), std::thread::{impl#0}::spawn_unchecked_::{closure#1}::{closure_env#0}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>>
                               at /usr/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9
  47:     0x3998d58f4cc0 - do_call<core::panic::unwind_safe::AssertUnwindSafe<std::thread::{impl#0}::spawn_unchecked_::{closure#1}::{closure_env#0}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/panicking.rs:589:40
  48:     0x3998d58f4cc0 - try<(), core::panic::unwind_safe::AssertUnwindSafe<std::thread::{impl#0}::spawn_unchecked_::{closure#1}::{closure_env#0}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>>>
                               at /usr/lib/rustlib/src/rust/library/std/src/panicking.rs:552:19
  49:     0x3998d58f4cc0 - catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<std::thread::{impl#0}::spawn_unchecked_::{closure#1}::{closure_env#0}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/panic.rs:359:14
  50:     0x3998d58f4cc0 - {closure#1}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
                               at /usr/lib/rustlib/src/rust/library/std/src/thread/mod.rs:557:30
  51:     0x3998d58f4cc0 - call_once<std::thread::{impl#0}::spawn_unchecked_::{closure_env#1}<rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>, ()>
                               at /usr/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  52:     0x3998da86c670 - std::sys::pal::unix::thread::Thread::new::thread_start::h62bfbd8292ec418b

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/adrian/rust/rustc-ice-2025-06-10T23_26_31-12576.txt` to your bug report

note: compiler flags: -C target-feature=-crt-static

I encountered this when running the testsuite natively, weirdly enough my stage0 compiler (rustc 1.88.0-nightly (d6a325d93 2025-05-03), cross compiled from x86_64 and dynamically linked) never crashes, but the natively compiled stage1 does. I immediately thought this may be an allocator issue, since my musl libc is patched to use mimalloc, but nope, mallocng (aka unmodified, "stock" musl malloc) musl also crashes.

The crash manifests in every couple of invocations - it sometimes compiles just fine, other times it will trigger the unsafe precondition evaluation, other times it will exit with SIGSEGV and no error message.

I'll try some older versions to see if this was a recent regression.

Things I tested so far: beta branch - also occurs

[Gelbpunkt]

One invocation that terminates in SIGSEGV in gdb:

is_singleton<rustc_ast::ast::Attribute> () at /home/adrian/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/thin-vec-0.2.14/src/lib.rs:1570
1570	        self.ptr.as_ptr() as *const Header == &EMPTY_HEADER

crashes here, so alignment is for sure wrong.

(gdb) x/10i $pc
=> 0x38362bea1c24 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+44>:	ldu     r5,112(r3)
   0x38362bea1c28 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+48>:	cmpld   r5,r4
   0x38362bea1c2c <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+52>:	std     r29,40(r31)
   0x38362bea1c30 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+56>:	bne     0x38362bea1c9c <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+164>
   0x38362bea1c34 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+60>:	addi    r3,r30,80
   0x38362bea1c38 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+64>:	bl      0x38362be9f9d0 <drop_in_place<rustc_ast::ast::Visibility>+8>
   0x38362bea1c3c <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+68>:	mr      r3,r30
   0x38362bea1c40 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+72>:	bl      0x38362bea4ec4 <drop_in_place<rustc_ast::ast::ItemKind>+8>
   0x38362bea1c44 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+76>:	ldu     r3,128(r30)
   0x38362bea1c48 <drop_in_place<rustc_ast::ast::Item<rustc_ast::ast::ItemKind>>+80>:	cmpldi  r3,0
(gdb) i r r3
r3             0x2000041e7         8589951463

that looks... very wrong.

I get ~16000/~19000 test fails at the moment, with ASLR disabled it's ~200 instead. All of these appear to be in thin-vec