rust-lang / rust-lang/rust

[ICE]: `OOM: failed to allocate for uninit check` -Zstrict-init-check

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A-const-eval C-bug I-ICE needs-triage T-compiler
Dominant language
Rust
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Description

snippet:

//@compile-flags: -Zalways-encode-mir -Zstrict-init-checks=yes
fn overflow() -> [[[bool; 9999999]; 777777777]; 239] {
    unsafe { core::mem::zeroed() }
}

fn main() {
    let _ = overflow();
}

Version information

rustc 1.99.0-nightly (49c80b5a0 2026-08-08)
binary: rustc
commit-hash: 49c80b5a0db8abd63315c04ff34f58629e388281
commit-date: 2026-08-08
host: x86_64-unknown-linux-gnu
release: 1.99.0-nightly
LLVM version: 23.1.0

Possibly related line of code:
https://github.com/rust-lang/rust/blob/49c80b5a0db8abd63315c04ff34f58629e388281/compiler/rustc_const_eval/src/util/check_validity_requirement.rs#L52-L64

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zalways-encode-mir -Zstrict-init-checks=yes

Program output 


thread 'rustc' (1112573) panicked at /rustc-dev/49c80b5a0db8abd63315c04ff34f58629e388281/compiler/rustc_const_eval/src/util/check_validity_requirement.rs:58:44:
OOM: failed to allocate for uninit check: InterpErrorInfo(InterpErrorInfoInner { kind: ResourceExhaustion(MemoryExhausted), backtrace: InterpErrorBacktrace { backtrace: None } })
stack backtrace:
   0:     0x7fa132f06146 - <<std[999cce9698cb2e30]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[611a668b6db07504]::fmt::Display>::fmt
   1:     0x7fa13361190f - core[611a668b6db07504]::fmt::write
   2:     0x7fa132f1b06c - <std[999cce9698cb2e30]::sys::stdio::unix::Stderr as core[611a668b6db07504]::io::write::Write>::write_fmt
   3:     0x7fa132ed91ba - std[999cce9698cb2e30]::panicking::default_hook::{closure#0}
   4:     0x7fa132ef9ed3 - std[999cce9698cb2e30]::panicking::default_hook
   5:     0x7fa131e3feaa - std[999cce9698cb2e30]::panicking::update_hook::<alloc[9c4b63ad13971f33]::boxed::Box<rustc_driver_impl[1d9b9be3672627fe]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7fa132efa372 - std[999cce9698cb2e30]::panicking::panic_with_hook
   7:     0x7fa132ed9272 - std[999cce9698cb2e30]::panicking::panic_handler::{closure#0}
   8:     0x7fa132ed1669 - std[999cce9698cb2e30]::sys::backtrace::__rust_end_short_backtrace::<std[999cce9698cb2e30]::panicking::panic_handler::{closure#0}, !>
   9:     0x7fa132edac4d - __rustc[a528db767ab46065]::rust_begin_unwind
  10:     0x7fa12fbc926c - core[611a668b6db07504]::panicking::panic_fmt
  11:     0x7fa12f3410c2 - core[611a668b6db07504]::result::unwrap_failed
  12:     0x7fa1314281c9 - rustc_const_eval[94f721029e7812d6]::util::check_validity_requirement::check_validity_requirement
  13:     0x7fa134a162d8 - rustc_query_impl[e0a7c844c3569b46]::query_impl::check_validity_requirement::invoke_provider_fn::__rust_begin_short_backtrace
  14:     0x7fa134a159b0 - rustc_query_impl[e0a7c844c3569b46]::execution::try_execute_query::<rustc_middle[842db40099f2c7a0]::query::caches::DefaultCache<(rustc_middle[842db40099f2c7a0]::ty::layout::ValidityRequirement, rustc_middle[842db40099f2c7a0]::ty::PseudoCanonicalInput<rustc_middle[842db40099f2c7a0]::ty::Ty>), rustc_middle[842db40099f2c7a0]::query::erase::ErasedData<[u8; 16usize]>>, false>
  15:     0x7fa134a15653 - rustc_query_impl[e0a7c844c3569b46]::query_impl::check_validity_requirement::execute_query_non_incr::__rust_end_short_backtrace
  16:     0x7fa134a8a62f - rustc_codegen_ssa[9d2ef248dbc53dd3]::mir::codegen_mir::<rustc_codegen_llvm[37ce2c06ea606dca]::builder::GenericBuilder<rustc_codegen_llvm[37ce2c06ea606dca]::context::FullCx>>
  17:     0x7fa133a5188f - rustc_codegen_llvm[37ce2c06ea606dca]::base::compile_codegen_unit::module_codegen
  18:     0x7fa1346a05b6 - <rustc_codegen_llvm[37ce2c06ea606dca]::LlvmCodegenBackend as rustc_codegen_ssa[9d2ef248dbc53dd3]::traits::backend::ExtraBackendMethods>::compile_codegen_unit
  19:     0x7fa13469c39a - rustc_codegen_ssa[9d2ef248dbc53dd3]::base::codegen_crate::<rustc_codegen_llvm[37ce2c06ea606dca]::LlvmCodegenBackend, rustc_codegen_llvm[37ce2c06ea606dca]::ModuleLlvm>
  20:     0x7fa13469ad4c - <rustc_codegen_llvm[37ce2c06ea606dca]::LlvmCodegenBackend as rustc_codegen_ssa[9d2ef248dbc53dd3]::traits::backend::CodegenBackend>::codegen_crate
  21:     0x7fa134828aa5 - <rustc_interface[1a36412a1dda276]::queries::Linker>::codegen_and_build_linker
  22:     0x7fa134820495 - rustc_interface[1a36412a1dda276]::interface::run_compiler::<(), rustc_driver_impl[1d9b9be3672627fe]::run_compiler::{closure#0}>::{closure#2}
  23:     0x7fa134855ca4 - std[999cce9698cb2e30]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[1a36412a1dda276]::util::run_in_thread_with_globals<rustc_interface[1a36412a1dda276]::util::run_in_thread_pool_with_globals<rustc_interface[1a36412a1dda276]::interface::run_compiler<(), rustc_driver_impl[1d9b9be3672627fe]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  24:     0x7fa134855a6d - <std[999cce9698cb2e30]::thread::lifecycle::spawn_unchecked<rustc_interface[1a36412a1dda276]::util::run_in_thread_with_globals<rustc_interface[1a36412a1dda276]::util::run_in_thread_pool_with_globals<rustc_interface[1a36412a1dda276]::interface::run_compiler<(), rustc_driver_impl[1d9b9be3672627fe]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[611a668b6db07504]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  25:     0x7fa13485323a - <std[999cce9698cb2e30]::sys::thread::unix::Thread>::new::thread_start
  26:     0x7fa12dc97739 - <unknown>
  27:     0x7fa12dd1bedc - <unknown>
  28:                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: please make sure that you have updated to the latest nightly

note: rustc 1.99.0-nightly (49c80b5a0 2026-08-08) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z always-encode-mir -Z strict-init-checks=yes -Z dump-mir-dir=dir

query stack during panic:
#0 [check_validity_requirement] checking validity requirement for `[[[bool; ValTree(Leaf(0x000000000098967f): usize)]; ValTree(Leaf(0x000000002e5bf271): usize)]; ValTree(Leaf(0x00000000000000ef): usize)]`: allows being left zeroed
end of query stack
note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: exhausted memory during interpretation
  |
  = note: delayed at /rustc-dev/49c80b5a0db8abd63315c04ff34f58629e388281/compiler/rustc_middle/src/mir/interpret/allocation.rs:466:43
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
             3: <rustc_errors::DiagCtxtHandle>::delayed_bug::<&str>
             4: <rustc_const_eval::interpret::eval_context::InterpCx<rustc_const_eval::const_eval::machine::CompileTimeMachine>>::allocate
             5: rustc_const_eval::util::check_validity_requirement::check_validity_requirement
             6: rustc_query_impl::query_impl::check_validity_requirement::invoke_provider_fn::__rust_begin_short_backtrace
             7: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefaultCache<(rustc_middle::ty::layout::ValidityRequirement, rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>), rustc_middle::query::erase::ErasedData<[u8; 16]>>, false>
             8: rustc_query_impl::query_impl::check_validity_requirement::execute_query_non_incr::__rust_end_short_backtrace
             9: rustc_codegen_ssa::mir::codegen_mir::<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
            10: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen
            11: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::ExtraBackendMethods>::compile_codegen_unit
            12: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_llvm::LlvmCodegenBackend, rustc_codegen_llvm::ModuleLlvm>
            13: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
            14: <rustc_interface::queries::Linker>::codegen_and_build_linker
            15: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#2}
            16: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            17: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            18: <std::sys::thread::unix::Thread>::new::thread_start
            19: <unknown>
            20: <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: please make sure that you have updated to the latest nightly

note: rustc 1.99.0-nightly (49c80b5a0 2026-08-08) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z always-encode-mir -Z strict-init-checks=yes -Z dump-mir-dir=dir

query stack during panic:
end of query stack

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the ICE with the provided snippet and -Zalways-encode-mir -Zstrict-init-checks=yes, then inspect compiler/rustc_const_eval/src/util/check_validity_requirement.rs around lines 52-64. Trace the check_validity_requirement path and confirm that the oversized array no longer causes an internal compiler error; the compiler should handle the resource exhaustion without panicking.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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