ICE: index out of bounds: the len is 0 but the index is 0 #136940

LennyPhoenix · 2025-02-12T19:03:13Z

rustc-ice-2025-02-12T19_02_34-223082.txt

Code

futures = "0.3.31"

#![feature(trait_alias)]

use futures::channel::mpsc::{channel, Sender};
use futures::future::BoxFuture;
use futures::StreamExt;
use std::future::Future;
use std::marker::PhantomData;

pub trait Spawn: Send {
    fn spawn(future: impl Future<Output = ()> + Send + 'static);
}

pub trait FnOnceTrait<'a, T: 'a, U> = FnOnce(&'a mut T) -> BoxFuture<'a, U> + Send + 'static;
pub type BoxFn<T> = Box<dyn for<'a> FnOnceTrait<'a, T, ()>>;

pub struct Critical<S, T>(Sender<BoxFn<T>>, PhantomData<S>);

impl<S: Spawn, T: Send + 'static> Critical<S, T> {
    pub fn new(mut value: T) -> Self {
        let (sink, mut stream) = channel::<BoxFn<T>>(1024);

        S::spawn(async move {
            while let Some(f) = stream.next().await {
                f(&mut value).await;
            }
        });

        Self(sink, PhantomData)
    }
}

Error output

   Compiling error_test v0.1.0 (/home/lenny/Projects/error_test)

thread 'rustc' panicked at compiler/rustc_infer/src/infer/mod.rs:1204:26:
index out of bounds: the len is 0 but the index is 0
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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/lenny/Projects/error_test/rustc-ice-2025-02-12T19_00_29-220361.txt` to your bug report

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

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

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `alloc::boxed::Box<(dyn for<'a> core::ops::function::FnOnce(&'a mut T) -> core::pin::Pin<alloc::boxed::Box<(dyn core::future:
:future::Future<Output = ()> + core::marker::Send + 'a)>> + core::marker::Send + 'b)>: core::ops::function::FnOnce<(^1_1,)>`
#1 [typeck] type-checking `<impl at src/main.rs:18:1: 18:49>::new`
... and 1 other queries... use `env RUST_BACKTRACE=1` to see the full query stack
error: could not compile `error_test` (bin "error_test")

Caused by:
  process didn't exit successfully: `/home/lenny/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc --crate-name error_test --edition=2021 src/main.rs --error-format=json --json
=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=188 --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-c
fg 'cfg(feature, values())' -C metadata=2766be39fb0fc4e7 -C extra-filename=-e06ef52b36ba5195 --out-dir /home/lenny/Projects/error_test/target/debug/deps -C incremental=/home/lenny/Projects
/error_test/target/debug/incremental -L dependency=/home/lenny/Projects/error_test/target/debug/deps --extern chrono=/home/lenny/Projects/error_test/target/debug/deps/libchrono-4f2b9403fa2
f8267.rlib --extern chrono_tz=/home/lenny/Projects/error_test/target/debug/deps/libchrono_tz-2bfc3c953512e5e9.rlib --extern futures=/home/lenny/Projects/error_test/target/debug/deps/libfut
ures-b2e5c549630d83b4.rlib --extern thiserror=/home/lenny/Projects/error_test/target/debug/deps/libthiserror-91714834ffdcbc83.rlib --extern tokio=/home/lenny/Projects/error_test/target/deb
ug/deps/libtokio-c4e8920040c3c7f3.rlib --extern tokio_stream=/home/lenny/Projects/error_test/target/debug/deps/libtokio_stream-e2c0de47bcea37dc.rlib --extern tokio_util=/home/lenny/Project
s/error_test/target/debug/deps/libtokio_util-858aafb43cee218e.rlib` (exit status: 101)

Backtrace

   Compiling error_test v0.1.0 (/home/lenny/Projects/error_test)

thread 'rustc' panicked at compiler/rustc_infer/src/infer/mod.rs:1204:26:
index out of bounds: the len is 0 but the index is 0
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic_bounds_check
   3: <rustc_middle::ty::fold::BoundVarReplacer<<rustc_infer::infer::InferCtxt>::instantiate_binder_with_fresh_vars::ToFreshVars> as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::conte
xt::TyCtxt>>::fold_ty
   4: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_middle::ty::fold::BoundVar
Replacer<<rustc_infer::infer::InferCtxt>::instantiate_binder_with_fresh_vars::ToFreshVars>>
   5: <rustc_middle::ty::fold::BoundVarReplacer<<rustc_infer::infer::InferCtxt>::instantiate_binder_with_fresh_vars::ToFreshVars> as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::conte
xt::TyCtxt>>::fold_ty
   6: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::generic_args::GenericArg> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_midd
le::ty::fold::BoundVarReplacer<<rustc_infer::infer::InferCtxt>::instantiate_binder_with_fresh_vars::ToFreshVars>>
   7: <rustc_infer::infer::InferCtxt>::instantiate_binder_with_fresh_vars::<rustc_type_ir::predicate::TraitRef<rustc_middle::ty::context::TyCtxt>>
   8: <rustc_trait_selection::traits::select::SelectionContext>::match_normalize_trait_ref
   9: <rustc_trait_selection::traits::select::SelectionContext>::candidate_from_obligation::{closure#0}::{closure#0}
  10: <rustc_trait_selection::traits::select::SelectionContext>::candidate_from_obligation::{closure#0}
  11: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_trait_predicate_recursively
  12: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_candidate::{closure#0}
  13: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_trait_predicate_recursively
  14: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_root_obligation
  15: rustc_traits::evaluate_obligation::evaluate_obligation
      [... omitted 1 frame ...]
  16: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation_no_overflow
  17: <rustc_hir_typeck::fn_ctxt::FnCtxt>::lookup_method_in_trait
  18: <rustc_hir_typeck::fn_ctxt::FnCtxt>::try_overloaded_call_traits
  19: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  20: <rustc_hir_typeck::fn_ctxt::FnCtxt>::confirm_builtin_call
  21: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  22: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_match::{closure#0}
  23: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  24: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_block
  25: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  26: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  27: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_block
  28: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  29: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_block
  30: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  31: rustc_hir_typeck::check::check_fn
  32: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_closure
  33: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  34: <rustc_hir_typeck::fn_ctxt::FnCtxt>::confirm_builtin_call
  35: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  36: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_block
  37: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  38: rustc_hir_typeck::check::check_fn
  39: rustc_hir_typeck::typeck_with_inspect::{closure#0}
      [... omitted 1 frame ...]
  40: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_hir_analysis::check_crate::{closure#3}>::{closure#0}
  41: rustc_hir_analysis::check_crate
  42: rustc_interface::passes::run_required_analyses
  43: rustc_interface::passes::analysis
      [... omitted 1 frame ...]
  44: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2
}::{closure#0}
  45: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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/lenny/Projects/error_test/rustc-ice-2025-02-12T19_01_14-220588.txt` to your bug report

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

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

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `alloc::boxed::Box<(dyn for<'a> core::ops::function::FnOnce(&'a mut T) -> core::pin::Pin<alloc::boxed::Box<(dyn core::future:
:future::Future<Output = ()> + core::marker::Send + 'a)>> + core::marker::Send + 'b)>: core::ops::function::FnOnce<(^1_1,)>`
#1 [typeck] type-checking `<impl at src/main.rs:18:1: 18:49>::new`
#2 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `error_test` (bin "error_test")

Caused by:
  process didn't exit successfully: `/home/lenny/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc --crate-name error_test --edition=2021 src/main.rs --error-format=json --json
=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=188 --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-c
fg 'cfg(feature, values())' -C metadata=2766be39fb0fc4e7 -C extra-filename=-e06ef52b36ba5195 --out-dir /home/lenny/Projects/error_test/target/debug/deps -C incremental=/home/lenny/Projects
/error_test/target/debug/incremental -L dependency=/home/lenny/Projects/error_test/target/debug/deps --extern chrono=/home/lenny/Projects/error_test/target/debug/deps/libchrono-4f2b9403fa2
f8267.rlib --extern chrono_tz=/home/lenny/Projects/error_test/target/debug/deps/libchrono_tz-2bfc3c953512e5e9.rlib --extern futures=/home/lenny/Projects/error_test/target/debug/deps/libfut
ures-b2e5c549630d83b4.rlib --extern thiserror=/home/lenny/Projects/error_test/target/debug/deps/libthiserror-91714834ffdcbc83.rlib --extern tokio=/home/lenny/Projects/error_test/target/deb
ug/deps/libtokio-c4e8920040c3c7f3.rlib --extern tokio_stream=/home/lenny/Projects/error_test/target/debug/deps/libtokio_stream-e2c0de47bcea37dc.rlib --extern tokio_util=/home/lenny/Project
s/error_test/target/debug/deps/libtokio_util-858aafb43cee218e.rlib` (exit status: 101)

The text was updated successfully, but these errors were encountered:

timmypidashev · 2025-02-12T19:23:27Z

The ICE seems to happen during trait selection when trying to handle higher-rank trait bounds (HRTB) with a trait alias. The empty slice access suggests it might be failing to properly handle the lifetimes or parameters in the trait selection process.

Specifically, when evaluating the trait selection:

evaluating trait selection obligation `alloc::boxed::Box<(dyn for<'a> core::ops::function::FnOnce(&'a mut T) -> core::pin::Pin<alloc::boxed::Box<(dyn core::future::future::Future<Output = ()> + core::marker::Send + 'a)>> + core::marker::Send + 'b)>: core::ops::function::FnOnce<(^1_1,)>`

I am way in over my head here, but I'll build the rust compiler locally and attempt to resolve a fix.

Seems the lead we have is the ranking of the trait bounds causing the panic...

cyrgani · 2025-02-12T19:52:06Z

Reduced:

#![feature(trait_alias)]
trait FnOnceTrait<'a> = FnOnce(&'a ());

fn g() -> Box<dyn for<'a> FnOnceTrait<'a>> {
    todo!()
}

fn main() {
    g().foo();
}

bisection:
searched nightlies: from nightly-2024-12-16 to nightly-2025-02-12
regressed nightly: nightly-2025-01-22
searched commit range: f3d1d47...ed43cbc
regressed commit: cd805f0

bisected with cargo-bisect-rustc v0.6.9

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --start=2024-12-16 --script=run.sh

@rustbot label:S-has-mcve S-has-bisection F-trait_alias

timmypidashev · 2025-02-12T22:41:30Z

bisection: searched nightlies: from nightly-2024-12-16 to nightly-2025-02-12 regressed nightly: nightly-2025-01-22 searched commit range: f3d1d47...ed43cbc regressed commit: cd805f0

bisected with cargo-bisect-rustc v0.6.9
@rustbot label:S-has-mcve S-has-bisection F-trait_alias

Great work. That commit in question was a fix pertaining to trait aliases.

I've never seen a bisection work so well before 🙂

lqd · 2025-02-12T22:59:48Z

cc @compiler-errors on that bisection

Use the right binder for rebinding `PolyTraitRef` Fixes rust-lang#136940 I committed a slightly different test which still demonstrates the issue.

Rollup merge of rust-lang#136951 - compiler-errors:clause-binder, r=lqd Use the right binder for rebinding `PolyTraitRef` Fixes rust-lang#136940 I committed a slightly different test which still demonstrates the issue.

LennyPhoenix added C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Feb 12, 2025

rustbot added the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Feb 12, 2025

LennyPhoenix changed the title ~~thread 'rustc' panicked at compiler/rustc_infer/src/infer/mod.rs~~ ICE: index out of bounds: the len is 0 but the index is 0 Feb 12, 2025

rustbot added S-has-mcve Status: A Minimal Complete and Verifiable Example has been found for this issue F-trait_alias `#![feature(trait_alias)]` S-has-bisection Status: a bisection has been found for this issue labels Feb 12, 2025

compiler-errors mentioned this issue Feb 12, 2025

Use the right binder for rebinding PolyTraitRef #136951

Merged

compiler-errors self-assigned this Feb 12, 2025

saethlin removed the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Feb 13, 2025

bors closed this as completed in 3957eaa Feb 14, 2025

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

ICE: index out of bounds: the len is 0 but the index is 0 #136940

ICE: index out of bounds: the len is 0 but the index is 0 #136940

LennyPhoenix commented Feb 12, 2025

timmypidashev commented Feb 12, 2025

cyrgani commented Feb 12, 2025 •

edited

Loading

timmypidashev commented Feb 12, 2025 •

edited

Loading

lqd commented Feb 12, 2025

ICE: index out of bounds: the len is 0 but the index is 0 #136940

ICE: index out of bounds: the len is 0 but the index is 0 #136940

Comments

LennyPhoenix commented Feb 12, 2025

Code

Meta

Error output

timmypidashev commented Feb 12, 2025

cyrgani commented Feb 12, 2025 • edited Loading

timmypidashev commented Feb 12, 2025 • edited Loading

lqd commented Feb 12, 2025

cyrgani commented Feb 12, 2025 •

edited

Loading

timmypidashev commented Feb 12, 2025 •

edited

Loading