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

[matthiaskrgr]

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:

rust/compiler/rustc_const_eval/src/util/check_validity_requirement.rs

Lines 52 to 64 in 49c80b5

	let machine = CompileTimeMachine::new(CanAccessMutGlobal::No, CheckAlignment::Error);
	let mut cx = InterpCx::new(cx.tcx(), DUMMY_SP, cx.typing_env, machine);
	// It doesn't really matter which `MemoryKind` we use here, `Stack` is the least wrong.
	let allocated =
	cx.allocate(ty, MemoryKind::Stack).expect("OOM: failed to allocate for uninit check");
	if kind == ValidityRequirement::Zero {
	cx.write_bytes_ptr(
	allocated.ptr(),
	std::iter::repeat_n(0_u8, ty.layout.size().bytes_usize()),
	)

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