rust-lang / rust-lang/rust

ICE: kcfi: encode_const: unexpected kind `UnevaluatedConst { .. }`

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C-bug F-generic_const_exprs I-ICE P-low T-compiler
Dominant language
Rust
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Description

auto-reduced (treereduce-rust):

#![feature(generic_const_exprs)]

use core::mem::MaybeUninit;

pub struct Arr<T, const N: usize> {
    v: [MaybeUninit<T>; N],
}

impl<T, const N: usize> Arr<T, N> {
    const ELEM: MaybeUninit<T> = MaybeUninit::uninit();
    const INIT: [MaybeUninit<T>; N] = [Self::ELEM; N];

    fn new() -> Self {
        Arr { v: Self::INIT }
    }
}

pub struct BaFormatFilter<const N: usize> {}

pub enum DigitalFilter<const N: usize>
where
    [(); N * 2 + 1]: Sized,
    [(); N * 2]: Sized,
{
    Ba(BaFormatFilter<{ N * 2 + 1 }>),
}

pub fn iirfilter_st_copy<const N: usize, const M: usize>(_: [f32; M]) -> DigitalFilter<N>
where
    [(); N * 2 + 1]: Sized,
    [(); N * 2]: Sized,
{
    let zpk = zpk2tf_st(&Arr::<f32, { N * 2 }>::new(), &Arr::<f32, { N * 2 }>::new());
    DigitalFilter::Ba(zpk)
}

pub fn zpk2tf_st<const N: usize>(_z: &Arr<f32, N>, _p: &Arr<f32, N>) -> BaFormatFilter<{ N + 1 }> {
    BaFormatFilter {}
}

fn main() {
    iirfilter_st_copy::<4, 2>([10., 50.]);
}


original code

original:

// issue: rust-lang/rust#106423
// ICE collection encountered polymorphic constant: UnevaluatedConst {..}
//@ edition:2021
//@ check-pass

#![feature(generic_const_exprs, generic_arg_infer)]
#![allow(incomplete_features)]
#![allow(unused)]

use core::mem::MaybeUninit;

pub struct Arr<T, const N: usize> {
    v: [MaybeUninit<T>; N],
}

impl<T, const N: usize> Arr<T, N> {
    const ELEM: MaybeUninit<T> = MaybeUninit::uninit();
    const INIT: [MaybeUninit<T>; N] = [Self::ELEM; N]; // important for optimization of `new`

    fn new() -> Self {
        Arr { v: Self::INIT }
    }
}

pub struct BaFormatFilter<const N: usize> {}

pub enum DigitalFilter<const N: usize>
where
    [(); N * 2 + 1]: Sized,
    [(); N * 2]: Sized,
{
    Ba(BaFormatFilter<{ N * 2 + 1 }>),
}

pub fn iirfilter_st_copy<const N: usize, const M: usize>(_: [f32; M]) -> DigitalFilter<N>
where
    [(); N * 2 + 1]: Sized,
    [(); N * 2]: Sized,
{
    let zpk = zpk2tf_st(&Arr::<f32, { N * 2 }>::new(), &Arr::<f32, { N * 2 }>::new());
    DigitalFilter::Ba(zpk)
}

pub fn zpk2tf_st<const N: usize>(
    _z: &Arr<f32, N>,
    _p: &Arr<f32, N>,
) -> BaFormatFilter<{ N + 1 }>
where
    [(); N + 1]: Sized,
{
    BaFormatFilter {}
}


fn main() {
    iirfilter_st_copy::<4, 2>([10., 50.,]);
}

Version information

rustc 1.81.0-nightly (7bb0ef490 2024-06-09)
binary: rustc
commit-hash: 7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a
commit-date: 2024-06-09
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zsanitizer=kcfi -Cpanic=abort --edition=2018

Program output

warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.gDgKBFsvnsak/rustc_testrunner_tmpdir_reporting.MRWKJmBGzCHY/mvce.rs:1:12
  |
1 | #![feature(generic_const_exprs, generic_arg_infer)]
  |            ^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
  = note: `#[warn(incomplete_features)]` on by default

warning: field `v` is never read
 --> /tmp/icemaker_global_tempdir.gDgKBFsvnsak/rustc_testrunner_tmpdir_reporting.MRWKJmBGzCHY/mvce.rs:6:5
  |
5 | pub struct Arr<T, const N: usize> {
  |            --- field in this struct
6 |     v: [MaybeUninit<T>; N],
  |     ^
  |
  = note: `#[warn(dead_code)]` on by default

error: internal compiler error: compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs:158:13: encode_const: unexpected kind `UnevaluatedConst { def: DefId(0:37 ~ mvce[64a8]::zpk2tf_st::{constant#0}), args: [(Mul: (4_usize: usize), (2_usize: usize))] }`

thread 'rustc' panicked at compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs:158:13:
Box<dyn Any>
stack backtrace:
   0:     0x78e6f81a5f15 - std::backtrace_rs::backtrace::libunwind::trace::heabb972c4bf30194
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x78e6f81a5f15 - std::backtrace_rs::backtrace::trace_unsynchronized::h4ba1442eaca1bb10
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x78e6f81a5f15 - std::sys_common::backtrace::_print_fmt::h4d12f471d77196b5
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x78e6f81a5f15 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hdafa2e62094a2544
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x78e6f81f6c5b - core::fmt::rt::Argument::fmt::h3bdee6e081605bf4
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/core/src/fmt/rt.rs:165:63
   5:     0x78e6f81f6c5b - core::fmt::write::h3a87f6a731d66d11
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/core/src/fmt/mod.rs:1168:21
   6:     0x78e6f819abef - std::io::Write::write_fmt::h639f79d09cf27b23
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/io/mod.rs:1835:15
   7:     0x78e6f81a5cee - std::sys_common::backtrace::_print::h8440f387a509d641
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x78e6f81a5cee - std::sys_common::backtrace::print::haf9fb54157ed196a
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x78e6f81a8729 - std::panicking::default_hook::{{closure}}::ha531e390acdea902
  10:     0x78e6f81a84ca - std::panicking::default_hook::h47e5185002a51d52
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/panicking.rs:298:9
  11:     0x78e6f49d673f - std[3073bd340ab08955]::panicking::update_hook::<alloc[4ecaa96cdf69b562]::boxed::Box<rustc_driver_impl[4e6b8414dae3c1cf]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x78e6f81a8e5b - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h32e30fee99996214
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/alloc/src/boxed.rs:2077:9
  13:     0x78e6f81a8e5b - std::panicking::rust_panic_with_hook::h73cccfbddee60476
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/panicking.rs:799:13
  14:     0x78e6f4a06f84 - std[3073bd340ab08955]::panicking::begin_panic::<rustc_errors[d1d8d20dbd2ccc21]::ExplicitBug>::{closure#0}
  15:     0x78e6f4a03a66 - std[3073bd340ab08955]::sys_common::backtrace::__rust_end_short_backtrace::<std[3073bd340ab08955]::panicking::begin_panic<rustc_errors[d1d8d20dbd2ccc21]::ExplicitBug>::{closure#0}, !>
  16:     0x78e6f49fee46 - std[3073bd340ab08955]::panicking::begin_panic::<rustc_errors[d1d8d20dbd2ccc21]::ExplicitBug>
  17:     0x78e6f4a105a1 - <rustc_errors[d1d8d20dbd2ccc21]::diagnostic::BugAbort as rustc_errors[d1d8d20dbd2ccc21]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x78e6f4ef9b3c - rustc_middle[a5a7a5d95a79c83]::util::bug::opt_span_bug_fmt::<rustc_span[fa5d72863ffc22f0]::span_encoding::Span>::{closure#0}
  19:     0x78e6f4ee2c6a - rustc_middle[a5a7a5d95a79c83]::ty::context::tls::with_opt::<rustc_middle[a5a7a5d95a79c83]::util::bug::opt_span_bug_fmt<rustc_span[fa5d72863ffc22f0]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x78e6f4ee2b0b - rustc_middle[a5a7a5d95a79c83]::ty::context::tls::with_context_opt::<rustc_middle[a5a7a5d95a79c83]::ty::context::tls::with_opt<rustc_middle[a5a7a5d95a79c83]::util::bug::opt_span_bug_fmt<rustc_span[fa5d72863ffc22f0]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x78e6f33fcc50 - rustc_middle[a5a7a5d95a79c83]::util::bug::bug_fmt
  22:     0x78e6f538582a - rustc_sanitizers[9a055dd07b406515]::cfi::typeid::itanium_cxx_abi::encode::encode_const
  23:     0x78e6f5385228 - rustc_sanitizers[9a055dd07b406515]::cfi::typeid::itanium_cxx_abi::encode::encode_args
  24:     0x78e6f5387f5c - rustc_sanitizers[9a055dd07b406515]::cfi::typeid::itanium_cxx_abi::encode::encode_ty
  25:     0x78e6f538dcf7 - rustc_sanitizers[9a055dd07b406515]::cfi::typeid::itanium_cxx_abi::typeid_for_fnabi
  26:     0x78e6f538e546 - rustc_sanitizers[9a055dd07b406515]::cfi::typeid::itanium_cxx_abi::typeid_for_instance
  27:     0x78e6f5386b2c - rustc_sanitizers[9a055dd07b406515]::kcfi::typeid::typeid_for_instance
  28:     0x78e6f330dd15 - <rustc_codegen_llvm[90f7dfbc3b8799f7]::context::CodegenCx as rustc_codegen_ssa[60af8791d0b2af86]::traits::declare::PreDefineMethods>::predefine_fn
  29:     0x78e6f6b2f861 - rustc_codegen_llvm[90f7dfbc3b8799f7]::base::compile_codegen_unit::module_codegen
  30:     0x78e6f6b2bbbc - <rustc_codegen_llvm[90f7dfbc3b8799f7]::LlvmCodegenBackend as rustc_codegen_ssa[60af8791d0b2af86]::traits::backend::ExtraBackendMethods>::compile_codegen_unit
  31:     0x78e6f6df87c1 - rustc_codegen_ssa[60af8791d0b2af86]::base::codegen_crate::<rustc_codegen_llvm[90f7dfbc3b8799f7]::LlvmCodegenBackend>
  32:     0x78e6f6c437ce - <rustc_codegen_llvm[90f7dfbc3b8799f7]::LlvmCodegenBackend as rustc_codegen_ssa[60af8791d0b2af86]::traits::backend::CodegenBackend>::codegen_crate
  33:     0x78e6f6c4315f - rustc_interface[b48fbfbbfca56691]::passes::start_codegen
  34:     0x78e6f6c427da - <rustc_interface[b48fbfbbfca56691]::queries::Queries>::codegen_and_build_linker
  35:     0x78e6f6a7cd32 - rustc_interface[b48fbfbbfca56691]::interface::run_compiler::<core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>, rustc_driver_impl[4e6b8414dae3c1cf]::run_compiler::{closure#0}>::{closure#1}
  36:     0x78e6f6a43a89 - std[3073bd340ab08955]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[b48fbfbbfca56691]::util::run_in_thread_with_globals<rustc_interface[b48fbfbbfca56691]::util::run_in_thread_pool_with_globals<rustc_interface[b48fbfbbfca56691]::interface::run_compiler<core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>, rustc_driver_impl[4e6b8414dae3c1cf]::run_compiler::{closure#0}>::{closure#1}, core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>>::{closure#0}, core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>>
  37:     0x78e6f6a43836 - <<std[3073bd340ab08955]::thread::Builder>::spawn_unchecked_<rustc_interface[b48fbfbbfca56691]::util::run_in_thread_with_globals<rustc_interface[b48fbfbbfca56691]::util::run_in_thread_pool_with_globals<rustc_interface[b48fbfbbfca56691]::interface::run_compiler<core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>, rustc_driver_impl[4e6b8414dae3c1cf]::run_compiler::{closure#0}>::{closure#1}, core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>>::{closure#0}, core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[be135d473bf2241c]::result::Result<(), rustc_span[fa5d72863ffc22f0]::ErrorGuaranteed>>::{closure#2} as core[be135d473bf2241c]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  38:     0x78e6f81b2e4b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h19ba87d856808e00
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/alloc/src/boxed.rs:2063:9
  39:     0x78e6f81b2e4b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hc37c884ba84dd5ac
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/alloc/src/boxed.rs:2063:9
  40:     0x78e6f81b2e4b - std::sys::pal::unix::thread::Thread::new::thread_start::h713e9186dc9dedf7
                               at /rustc/7bb0ef4902e43f338aa73c3ff728bea3cb9ecf6a/library/std/src/sys/pal/unix/thread.rs:108:17
  41:     0x78e6f16a6ded - <unknown>
  42:     0x78e6f172a0dc - <unknown>
  43:                0x0 - <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 1.81.0-nightly (7bb0ef490 2024-06-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z sanitizer=kcfi -C panic=abort -Z dump-mir-dir=dir

query stack during panic:
end of query stack
error: aborting due to 1 previous error; 2 warnings emitted


@rustbot label +F-generic_const_exprs +F-generic_arg_infer

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Research direction

Reproduce the reduced program with the reported rustc command, then inspect compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs, especially encode_const and its callers. The work is done when the kcfi compilation no longer ICEs on the reported UnevaluatedConst case and the reduced reproduction behaves correctly.

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
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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