/snapshot_vec.rs:199:10: index out of bounds: the len is 29 but the index is 30

[AlterionX]

ICE during compilation, was told by compiler to report here. I think I noticed a few that looked similar, like #114056 but they're old.

Code

I'm having trouble trying to minimize it and I'll work on it if I can get my actual task done first. Mentioning it anyways though.

Meta

rustc --version --verbose:

rustc 1.90.0-nightly (bfc046a4b 2025-07-12)
binary: rustc
commit-hash: bfc046a4b8d6b57db02540182466e989a9b0fb40
commit-date: 2025-07-12
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.7

Error output

thread 'rustc' panicked at /rust/deps/ena-0.14.3/src/snapshot_vec.rs:199:10:
index out of bounds: the len is 29 but the index is 30

Backtrace

thread 'rustc' panicked at /rust/deps/ena-0.14.3/src/snapshot_vec.rs:199:10:
index out of bounds: the len is 29 but the index is 30
stack backtrace:
   0:     0x70fd175a34b5 - std::backtrace::Backtrace::create::h60a32b542fd734a7
   1:     0x70fd175a3405 - std::backtrace::Backtrace::force_capture::h6a06312b88382d95
   2:     0x70fd1665c21e - std[34cb40b60ac2ba15]::panicking::update_hook::<alloc[7bbc98ec2376e8c9]::boxed::Box<rustc_driver_impl[f0d37e15138f6367]::install_ice_hook::{closure#1}>>::{closure#0}
   3:     0x70fd175bd49e - std::panicking::rust_panic_with_hook::h04f220ce84e2ef62
   4:     0x70fd175bd19a - std::panicking::begin_panic_handler::{{closure}}::hda4612fe3861e9e3
   5:     0x70fd175b9819 - std::sys::backtrace::__rust_end_short_backtrace::h967b627aba554184
   6:     0x70fd175bce7d - __rustc[acf2af34d2fb84a0]::rust_begin_unwind
   7:     0x70fd13ce59f0 - core::panicking::panic_fmt::hc884facc23b44f92
   8:     0x70fd15b70d3d - core::panicking::panic_bounds_check::hbf39af2a8c59853b
   9:     0x70fd19633a15 - <ena[b0fac6750ea13b73]::unify::UnificationTable<ena[b0fac6750ea13b73]::unify::backing_vec::InPlace<rustc_infer[2930c2a7f4cb6102]::infer::type_variable::TyVidEqKey, &mut alloc[7bbc98ec2376e8c9]::vec::Vec<ena[b0fac6750ea13b73]::unify::VarValue<rustc_infer[2930c2a7f4cb6102]::infer::type_variable::TyVidEqKey>>, &mut rustc_infer[2930c2a7f4cb6102]::infer::snapshot::undo_log::InferCtxtUndoLogs>>>::uninlined_get_root_key.cold
  10:     0x70fd18429e8f - <rustc_infer[2930c2a7f4cb6102]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[9ccf4b997baa19a]::fold::TypeFolder<rustc_middle[b8ff1d89356f2e34]::ty::context::TyCtxt>>::fold_ty
  11:     0x70fd1842a88c - <rustc_infer[2930c2a7f4cb6102]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[9ccf4b997baa19a]::fold::TypeFolder<rustc_middle[b8ff1d89356f2e34]::ty::context::TyCtxt>>::fold_ty
  12:     0x70fd1842c143 - <rustc_infer[2930c2a7f4cb6102]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[9ccf4b997baa19a]::fold::TypeFolder<rustc_middle[b8ff1d89356f2e34]::ty::context::TyCtxt>>::fold_ty
  13:     0x70fd18428f0c - <rustc_infer[2930c2a7f4cb6102]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[9ccf4b997baa19a]::fold::TypeFolder<rustc_middle[b8ff1d89356f2e34]::ty::context::TyCtxt>>::fold_predicate
  14:     0x70fd18421606 - <rustc_infer[2930c2a7f4cb6102]::infer::InferCtxt as rustc_trait_selection[f5828d9d7a160177]::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
  15:     0x70fd168c0253 - <rustc_infer[2930c2a7f4cb6102]::infer::InferCtxt as rustc_trait_selection[f5828d9d7a160177]::infer::InferCtxtExt>::type_implements_trait::<&rustc_middle[b8ff1d89356f2e34]::ty::list::RawList<(), rustc_middle[b8ff1d89356f2e34]::ty::generic_args::GenericArg>>
  16:     0x70fd16994379 - <rustc_hir_typeck[ab14d4b50192b6cc]::fn_ctxt::FnCtxt>::report_no_match_method_error
  17:     0x70fd169d5c6c - <rustc_hir_typeck[ab14d4b50192b6cc]::fn_ctxt::FnCtxt>::report_method_error
  18:     0x70fd18bd2ad7 - <rustc_hir_typeck[ab14d4b50192b6cc]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  19:     0x70fd18ba9c4c - <rustc_hir_typeck[ab14d4b50192b6cc]::fn_ctxt::FnCtxt>::check_expr_block
  20:     0x70fd18bc423c - <rustc_hir_typeck[ab14d4b50192b6cc]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  21:     0x70fd18bb463a - rustc_hir_typeck[ab14d4b50192b6cc]::check::check_fn
  22:     0x70fd18fe43c8 - rustc_hir_typeck[ab14d4b50192b6cc]::typeck_with_inspect::{closure#0}
  23:     0x70fd18fd0db0 - rustc_query_impl[c494d85a0db2d964]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c494d85a0db2d964]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b8ff1d89356f2e34]::query::erase::Erased<[u8; 8usize]>>
  24:     0x70fd17f7f579 - rustc_query_system[5b0e4c71bbae79fa]::query::plumbing::try_execute_query::<rustc_query_impl[c494d85a0db2d964]::DynamicConfig<rustc_data_structures[a5a6da643927d733]::vec_cache::VecCache<rustc_span[9d5e1a90c38b9a5b]::def_id::LocalDefId, rustc_middle[b8ff1d89356f2e34]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[5b0e4c71bbae79fa]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[c494d85a0db2d964]::plumbing::QueryCtxt, true>
  25:     0x70fd17f48240 - rustc_query_impl[c494d85a0db2d964]::query_impl::typeck::get_query_incr::__rust_end_short_backtrace
  26:     0x70fd184cd184 - rustc_hir_analysis[cee1fc65ba31447b]::check_crate
  27:     0x70fd1876f1a3 - rustc_interface[415067217794e818]::passes::analysis
  28:     0x70fd1876edb3 - rustc_query_impl[c494d85a0db2d964]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c494d85a0db2d964]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b8ff1d89356f2e34]::query::erase::Erased<[u8; 0usize]>>
  29:     0x70fd190ae402 - rustc_query_system[5b0e4c71bbae79fa]::query::plumbing::try_execute_query::<rustc_query_impl[c494d85a0db2d964]::DynamicConfig<rustc_query_system[5b0e4c71bbae79fa]::query::caches::SingleCache<rustc_middle[b8ff1d89356f2e34]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[c494d85a0db2d964]::plumbing::QueryCtxt, true>
  30:     0x70fd190add23 - rustc_query_impl[c494d85a0db2d964]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  31:     0x70fd190e0e16 - rustc_interface[415067217794e818]::passes::create_and_enter_global_ctxt::<core[21e84e4d8dde3a3c]::option::Option<rustc_interface[415067217794e818]::queries::Linker>, rustc_driver_impl[f0d37e15138f6367]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  32:     0x70fd190d2e57 - rustc_interface[415067217794e818]::interface::run_compiler::<(), rustc_driver_impl[f0d37e15138f6367]::run_compiler::{closure#0}>::{closure#1}
  33:     0x70fd18fac2f8 - std[34cb40b60ac2ba15]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[415067217794e818]::util::run_in_thread_with_globals<rustc_interface[415067217794e818]::util::run_in_thread_pool_with_globals<rustc_interface[415067217794e818]::interface::run_compiler<(), rustc_driver_impl[f0d37e15138f6367]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  34:     0x70fd18fabfd6 - <<std[34cb40b60ac2ba15]::thread::Builder>::spawn_unchecked_<rustc_interface[415067217794e818]::util::run_in_thread_with_globals<rustc_interface[415067217794e818]::util::run_in_thread_pool_with_globals<rustc_interface[415067217794e818]::interface::run_compiler<(), rustc_driver_impl[f0d37e15138f6367]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[21e84e4d8dde3a3c]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  35:     0x70fd18fada3d - std::sys::pal::unix::thread::Thread::new::thread_start::h149e058f4fe6a285
  36:     0x70fd12694ac3 - start_thread
                               at ./nptl/pthread_create.c:442:8
  37:     0x70fd12726850 - __GI___clone3
                               at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81:0
  38:                0x0 - <unknown>


rustc version: 1.90.0-nightly (bfc046a4b 2025-07-12)
platform: x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `login::<impl at server/src/login.rs:57:1: 57:45>::into_response`
#1 [analysis] running analysis passes on this crate
end of query stack

rustc-ice-2025-07-13T02_58_45-451205.txt

[fmease]

I'm having trouble trying to minimize it and I'll work on it if I can get my actual task done first.

Makes sense. If your code base isn't proprietary, you could also simply post a link to a public repository + git commit + reproduction steps and we'll do the minimization for you.

Mentioning it anyways though.

Thanks!

[AlterionX]

https://github.com/AlterionX/icebug-2025-07-12 managed to grab the relevant bits out, also managed to minimize it (isolating it was faster than I thought; relevant code was actually isolated to a specific commit I had on my end and I had to fix it when doing what I was doing anyways)

[fmease]

Smaller:

fn basic() -> Response {
    ((), std::collections::HashMap::new()).into_response()
}

fn main() {}

struct Response;

trait IntoResponse {
    fn into_response(self) -> Response;
}

impl<T, U> IntoResponse for (T, U)
where
    U: IntoResponse,
{
    fn into_response(self) -> Response {
        loop {}
    }
}

[fmease]

Even smaller:

trait Trait {
    fn meth(self);
}

impl<T, U: Trait> Trait for (T, U) {
    fn meth(self) {}
}

fn main() {
    ((), std::collections::HashMap::new()).meth()
}

[cyrgani]

duplicate of #142488?