ICE while compiling diesel

Hello everyone, I got this ICE today, but unfortunately I cannot reproduce the error. It just worked on the second try.

rustc --version --verbose:

rustc 1.91.0 (f8297e351 2025-10-28)
binary: rustc
commit-hash: f8297e351a40c1439a467bbbb6879088047f50b3
commit-date: 2025-10-28
host: x86_64-unknown-linux-gnu
release: 1.91.0
LLVM version: 21.1.2

Error output

thread 'rustc' (104872) panicked at compiler/rustc_metadata/src/creader.rs:242:31:
index out of bounds: the len is 29 but the index is 3233284272
stack backtrace:
   0:     0x7f8c76650a23 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h4e0a3aeea0f9c085
   1:     0x7f8c76e01bd8 - core::fmt::write::hecf68a131630c74d
   2:     0x7f8c784b57af - std::io::Write::write_fmt::h93c9a261259c931a
   3:     0x7f8c76615ee2 - std::sys::backtrace::BacktraceLock::print::h75160192768e5621
   4:     0x7f8c7661be39 - std::panicking::default_hook::{{closure}}::h14d82797cfb1ddcb
   5:     0x7f8c7661b963 - std::panicking::default_hook::h63f9bf8161c5d325
   6:     0x7f8c756024e7 - std[752e03a6421f8218]::panicking::update_hook::<alloc[cb649fc9a76fa509]::boxed::Box<rustc_driver_impl[7060c14ee153e4be]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7f8c7661c25f - std::panicking::panic_with_hook::h3173740e06bd0752
   8:     0x7f8c7661c01a - std::panicking::panic_handler::{{closure}}::hbac492c61eb56a87
   9:     0x7f8c76616029 - std::sys::backtrace::__rust_end_short_backtrace::haa3eac3df9535320
  10:     0x7f8c765f698d - __rustc[de0091b922c53d7e]::rust_begin_unwind
  11:     0x7f8c72ce7940 - core::panicking::panic_fmt::h5138da2ef87be35b
  12:     0x7f8c74cdbab3 - core::panicking::panic_bounds_check::h9bbcb0758914da05
  13:     0x7f8c77a85925 - rustc_metadata[49038a60e10b3943]::rmeta::decoder::cstore_impl::provide_extern::const_conditions
  14:     0x7f8c77a85357 - rustc_query_impl[105cc161e39911be]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[105cc161e39911be]::query_impl::const_conditions::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 24usize]>>
  15:     0x7f8c77a85321 - <rustc_query_impl[105cc161e39911be]::query_impl::const_conditions::dynamic_query::{closure#2} as core[23fa5c620bd8b707]::ops::function::FnOnce<(rustc_middle[d4b0c03c541beb2b]::ty::context::TyCtxt, rustc_span[56f068732132fb52]::def_id::DefId)>>::call_once
  16:     0x7f8c76fafa78 - rustc_query_system[eecf37c567c7c9f0]::query::plumbing::try_execute_query::<rustc_query_impl[105cc161e39911be]::DynamicConfig<rustc_query_system[eecf37c567c7c9f0]::query::caches::DefIdCache<rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[105cc161e39911be]::plumbing::QueryCtxt, false>
  17:     0x7f8c77640970 - rustc_query_impl[105cc161e39911be]::query_impl::const_conditions::get_query_non_incr::__rust_end_short_backtrace
  18:     0x7f8c77640baf - <rustc_middle[d4b0c03c541beb2b]::ty::generics::ConstConditions>::instantiate_identity_into
  19:     0x7f8c776400fa - rustc_ty_utils[1ab6fa071a2a29fa]::ty::param_env
  20:     0x7f8c7763ec3d - rustc_query_impl[105cc161e39911be]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[105cc161e39911be]::query_impl::param_env::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 8usize]>>
  21:     0x7f8c76e1abb9 - rustc_query_system[eecf37c567c7c9f0]::query::plumbing::try_execute_query::<rustc_query_impl[105cc161e39911be]::DynamicConfig<rustc_query_system[eecf37c567c7c9f0]::query::caches::DefIdCache<rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[105cc161e39911be]::plumbing::QueryCtxt, false>
  22:     0x7f8c76e1a69d - rustc_query_impl[105cc161e39911be]::query_impl::param_env::get_query_non_incr::__rust_end_short_backtrace
  23:     0x7f8c76fad8b6 - rustc_query_impl[105cc161e39911be]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[105cc161e39911be]::query_impl::typing_env_normalized_for_post_analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 24usize]>>
  24:     0x7f8c76fad5a9 - <rustc_query_impl[105cc161e39911be]::query_impl::typing_env_normalized_for_post_analysis::dynamic_query::{closure#2} as core[23fa5c620bd8b707]::ops::function::FnOnce<(rustc_middle[d4b0c03c541beb2b]::ty::context::TyCtxt, rustc_span[56f068732132fb52]::def_id::DefId)>>::call_once
  25:     0x7f8c76fafa78 - rustc_query_system[eecf37c567c7c9f0]::query::plumbing::try_execute_query::<rustc_query_impl[105cc161e39911be]::DynamicConfig<rustc_query_system[eecf37c567c7c9f0]::query::caches::DefIdCache<rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[105cc161e39911be]::plumbing::QueryCtxt, false>
  26:     0x7f8c76faf1a2 - rustc_query_impl[105cc161e39911be]::query_impl::typing_env_normalized_for_post_analysis::get_query_non_incr::__rust_end_short_backtrace
  27:     0x7f8c77c0442b - <rustc_middle[d4b0c03c541beb2b]::ty::TypingEnv>::post_analysis::<rustc_span[56f068732132fb52]::def_id::DefId>
  28:     0x7f8c77c02e00 - rustc_mir_transform[66c6cad113eb7cce]::shim::build_adt_ctor
  29:     0x7f8c77a66196 - rustc_mir_transform[66c6cad113eb7cce]::optimized_mir
  30:     0x7f8c77a65d5d - rustc_query_impl[105cc161e39911be]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[105cc161e39911be]::query_impl::optimized_mir::dynamic_query::{closure#2}::{closure#0}, rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 8usize]>>
  31:     0x7f8c76e1abb9 - rustc_query_system[eecf37c567c7c9f0]::query::plumbing::try_execute_query::<rustc_query_impl[105cc161e39911be]::DynamicConfig<rustc_query_system[eecf37c567c7c9f0]::query::caches::DefIdCache<rustc_middle[d4b0c03c541beb2b]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[105cc161e39911be]::plumbing::QueryCtxt, false>
  32:     0x7f8c76e1a05b - rustc_query_impl[105cc161e39911be]::query_impl::optimized_mir::get_query_non_incr::__rust_end_short_backtrace
  33:     0x7f8c7777bee0 - <rustc_metadata[49038a60e10b3943]::rmeta::encoder::EncodeContext>::encode_crate_root
  34:     0x7f8c783af494 - <rustc_metadata[49038a60e10b3943]::rmeta::encoder::encode_metadata::{closure#3} as core[23fa5c620bd8b707]::ops::function::FnOnce<(rustc_middle[d4b0c03c541beb2b]::ty::context::TyCtxt, &std[752e03a6421f8218]::path::Path)>>::call_once
  35:     0x7f8c783ac250 - rustc_metadata[49038a60e10b3943]::rmeta::encoder::encode_metadata
  36:     0x7f8c77d0f223 - rustc_metadata[49038a60e10b3943]::fs::encode_and_write_metadata
  37:     0x7f8c780c0f69 - <rustc_interface[356b87dbb86a0c69]::queries::Linker>::codegen_and_build_linker
  38:     0x7f8c780bead5 - rustc_interface[356b87dbb86a0c69]::passes::create_and_enter_global_ctxt::<core[23fa5c620bd8b707]::option::Option<rustc_interface[356b87dbb86a0c69]::queries::Linker>, rustc_driver_impl[7060c14ee153e4be]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  39:     0x7f8c780ae6be - rustc_interface[356b87dbb86a0c69]::interface::run_compiler::<(), rustc_driver_impl[7060c14ee153e4be]::run_compiler::{closure#0}>::{closure#1}
  40:     0x7f8c77fde7b8 - std[752e03a6421f8218]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[356b87dbb86a0c69]::util::run_in_thread_with_globals<rustc_interface[356b87dbb86a0c69]::util::run_in_thread_pool_with_globals<rustc_interface[356b87dbb86a0c69]::interface::run_compiler<(), rustc_driver_impl[7060c14ee153e4be]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  41:     0x7f8c77fde49c - <<std[752e03a6421f8218]::thread::Builder>::spawn_unchecked_<rustc_interface[356b87dbb86a0c69]::util::run_in_thread_with_globals<rustc_interface[356b87dbb86a0c69]::util::run_in_thread_pool_with_globals<rustc_interface[356b87dbb86a0c69]::interface::run_compiler<(), rustc_driver_impl[7060c14ee153e4be]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[23fa5c620bd8b707]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  42:     0x7f8c77fe4a6f - std::sys::thread::unix::Thread::new::thread_start::h38da0f633f090ce2
  43:     0x7f8c7169698b - <unknown>
  44:     0x7f8c7171a9cc - <unknown>
  45:                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: rustc 1.91.0 (f8297e351 2025-10-28) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C target-cpu=native

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

query stack during panic:
panicked at compiler/rustc_metadata/src/creader.rs:242:31:

thread panicked while processing panic. aborting.
error: could not compile `diesel` (lib)

Caused by:
  process didn't exit successfully: `/home/.../.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name diesel --edition=2021 /home/.../.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/diesel-2.3.2/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=257 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --cfg 'feature="32-column-tables"' --cfg 'feature="chrono"' --cfg 'feature="default"' --cfg 'feature="returning_clauses_for_sqlite_3_35"' --cfg 'feature="sqlite"' --cfg 'feature="with-deprecated"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("128-column-tables", "32-column-tables", "64-column-tables", "__with_asan_tests", "chrono", "default", "extras", "huge-tables", "i-implement-a-third-party-backend-and-opt-into-breaking-changes", "ipnet-address", "large-tables", "mysql", "mysql_backend", "mysqlclient-src", "network-address", "numeric", "postgres", "postgres_backend", "pq-src", "quickcheck", "r2d2", "returning_clauses_for_sqlite_3_35", "serde_json", "sqlite", "time", "unstable", "uuid", "with-deprecated", "without-deprecated"))' -C metadata=e23e6c90b40f543c -C extra-filename=-963123a2833e7bf7 --out-dir /home/.../target/debug/deps -L dependency=/home/.../target/debug/deps --extern chrono=/home/.../target/debug/deps/libchrono-a49e19a7472d3b8e.rmeta --extern diesel_derives=/home/.../target/debug/deps/libdiesel_derives-8a36cd024897441e.so --extern downcast_rs=/home/.../target/debug/deps/libdowncast_rs-518f2c82c51df6e9.rmeta --extern libsqlite3_sys=/home/.../target/debug/deps/liblibsqlite3_sys-52b4e39350101cc8.rmeta --cap-lints allow -C target-cpu=native -L native=/home/.../target/debug/build/libsqlite3-sys-efaf715ab56af74b/out` (signal: 6, SIGABRT: process abort signal)

Start by trying to reproduce the ICE while compiling Diesel 2.3.2 with rustc 1.91.0 on x86_64-unknown-linux-gnu and the reported flags. Inspect compiler/rustc_metadata/src/creader.rs:242:31 and the query stack around const_conditions; done means obtaining a minimal reproducible case and identifying a confirmed compiler fix or diagnostic path.