regression: thread 'rustc' panicked, assertion `left != right` failed

[BoxyUwU]

• https://crater-reports.s3.amazonaws.com/beta-1.88-1/beta-2025-05-26/gh/andhieSetyabudi.mcuboot/log.txt

[INFO] [stderr] thread 'rustc' panicked at compiler/rustc_span/src/symbol.rs:2356:9:
[INFO] [stderr] assertion `left != right` failed
[INFO] [stderr]   left: ""
[INFO] [stderr]  right: ""
[INFO] [stderr] stack backtrace:
[INFO] [stderr]    0:     0x752bb8549f33 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h6bed9dc66a5cec52
[INFO] [stderr]    1:     0x752bb8c05947 - core::fmt::write::h7d74dd6e449cae1f
[INFO] [stderr]    2:     0x752bb9cd7791 - std::io::Write::write_fmt::h68b3bc9d54a39d7f
[INFO] [stderr]    3:     0x752bb8549d92 - std::sys::backtrace::BacktraceLock::print::h6b5cffc33d0e9592
[INFO] [stderr]    4:     0x752bb854d98a - std::panicking::default_hook::{{closure}}::h5fc51e281b0877ca
[INFO] [stderr]    5:     0x752bb854d50f - std::panicking::default_hook::h03c499ee84a534f3
[INFO] [stderr]    6:     0x752bb75787b3 - std[4ece947bc34e96db]::panicking::update_hook::<alloc[fd9347d1b2560651]::boxed::Box<rustc_driver_impl[994997776c209ede]::install_ice_hook::{closure#1}>>::{closure#0}
[INFO] [stderr]    7:     0x752bb854e203 - std::panicking::rust_panic_with_hook::ha891520ba817caf1
[INFO] [stderr]    8:     0x752bb854defa - std::panicking::begin_panic_handler::{{closure}}::ha3354180cd64890f
[INFO] [stderr]    9:     0x752bb854a3f9 - std::sys::backtrace::__rust_end_short_backtrace::h3bc1bfbcac42a3a6
[INFO] [stderr]   10:     0x752bb854dbbd - __rustc[e3a6421a38efca84]::rust_begin_unwind
[INFO] [stderr]   11:     0x752bb4e85de0 - core::panicking::panic_fmt::h6ea58fee8777a3d1
[INFO] [stderr]   12:     0x752bb6efa17a - core::panicking::assert_failed_inner::h3da719a85b51b663
[INFO] [stderr]   13:     0x752bb6e30670 - core[bdde32e857371a49]::panicking::assert_failed::<rustc_span[ade2e571dc313a2f]::symbol::Symbol, rustc_span[ade2e571dc313a2f]::symbol::Symbol>
[INFO] [stderr]   14:     0x752bb95499da - <rustc_span[ade2e571dc313a2f]::symbol::Symbol>::to_ident_string
[INFO] [stderr]   15:     0x752bb9ad5438 - <rustc_errors[3e37cc015d94a130]::diagnostic::DiagInner>::arg::<&str, rustc_span[ade2e571dc313a2f]::symbol::Symbol>
[INFO] [stderr]   16:     0x752bb9ad4a56 - <rustc_lint[809156708517efa4]::lints::UnexpectedCfgValue as rustc_errors[3e37cc015d94a130]::diagnostic::LintDiagnostic<()>>::decorate_lint
[INFO] [stderr]   17:     0x752bb9ad56e6 - rustc_lint[809156708517efa4]::early::diagnostics::decorate_lint
[INFO] [stderr]   18:     0x752bb9ad55cc - <<rustc_lint[809156708517efa4]::early::EarlyContextAndPass<rustc_lint[809156708517efa4]::BuiltinCombinedEarlyLintPass>>::inlined_check_id::{closure#0} as core[bdde32e857371a49]::ops::function::FnOnce<(&mut rustc_errors[3e37cc015d94a130]::diagnostic::Diag<()>,)>>::call_once::{shim:vtable#0}
[INFO] [stderr]   19:     0x752bb939d210 - rustc_middle[78f1cb797b32985a]::lint::lint_level::lint_level_impl
[INFO] [stderr]   20:     0x752bb984dc7c - rustc_interface[debe5311a742862e]::passes::early_lint_checks
[INFO] [stderr]   21:     0x752bb984d38d - rustc_query_impl[5215c5451aacabe]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[5215c5451aacabe]::query_impl::early_lint_checks::dynamic_query::{closure#2}::{closure#0}, rustc_middle[78f1cb797b32985a]::query::erase::Erased<[u8; 0usize]>>
[INFO] [stderr]   22:     0x752bb9b1253a - rustc_query_system[3588958cd15a526e]::query::plumbing::try_execute_query::<rustc_query_impl[5215c5451aacabe]::DynamicConfig<rustc_query_system[3588958cd15a526e]::query::caches::SingleCache<rustc_middle[78f1cb797b32985a]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[5215c5451aacabe]::plumbing::QueryCtxt, false>
[INFO] [stderr]   23:     0x752bb9b12299 - rustc_query_impl[5215c5451aacabe]::query_impl::early_lint_checks::get_query_non_incr::__rust_end_short_backtrace
[INFO] [stderr]   24:     0x752bb90c0e6a - rustc_ast_lowering[db5f2990f914eadc]::lower_to_hir
[INFO] [stderr]   25:     0x752bb9acbb2a - rustc_query_impl[5215c5451aacabe]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[5215c5451aacabe]::query_impl::hir_crate::dynamic_query::{closure#2}::{closure#0}, rustc_middle[78f1cb797b32985a]::query::erase::Erased<[u8; 8usize]>>
[INFO] [stderr]   26:     0x752bb9b14901 - rustc_query_system[3588958cd15a526e]::query::plumbing::try_execute_query::<rustc_query_impl[5215c5451aacabe]::DynamicConfig<rustc_query_system[3588958cd15a526e]::query::caches::SingleCache<rustc_middle[78f1cb797b32985a]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[5215c5451aacabe]::plumbing::QueryCtxt, false>
[INFO] [stderr]   27:     0x752bb9b13d88 - rustc_query_impl[5215c5451aacabe]::query_impl::hir_crate::get_query_non_incr::__rust_end_short_backtrace
[INFO] [stderr]   28:     0x752bb974215c - rustc_interface[debe5311a742862e]::passes::run_required_analyses
[INFO] [stderr]   29:     0x752bb9b1045e - rustc_interface[debe5311a742862e]::passes::analysis
[INFO] [stderr]   30:     0x752bb9b10435 - rustc_query_impl[5215c5451aacabe]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[5215c5451aacabe]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[78f1cb797b32985a]::query::erase::Erased<[u8; 0usize]>>
[INFO] [stderr]   31:     0x752bb9b1253a - rustc_query_system[3588958cd15a526e]::query::plumbing::try_execute_query::<rustc_query_impl[5215c5451aacabe]::DynamicConfig<rustc_query_system[3588958cd15a526e]::query::caches::SingleCache<rustc_middle[78f1cb797b32985a]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[5215c5451aacabe]::plumbing::QueryCtxt, false>
[INFO] [stderr]   32:     0x752bb9b1220f - rustc_query_impl[5215c5451aacabe]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
[INFO] [stderr]   33:     0x752bb9de1447 - rustc_interface[debe5311a742862e]::passes::create_and_enter_global_ctxt::<core[bdde32e857371a49]::option::Option<rustc_interface[debe5311a742862e]::queries::Linker>, rustc_driver_impl[994997776c209ede]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
[INFO] [stderr]   34:     0x752bb9d26566 - rustc_interface[debe5311a742862e]::interface::run_compiler::<(), rustc_driver_impl[994997776c209ede]::run_compiler::{closure#0}>::{closure#1}
[INFO] [stderr]   35:     0x752bb9ccb3be - std[4ece947bc34e96db]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[debe5311a742862e]::util::run_in_thread_with_globals<rustc_interface[debe5311a742862e]::util::run_in_thread_pool_with_globals<rustc_interface[debe5311a742862e]::interface::run_compiler<(), rustc_driver_impl[994997776c209ede]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
[INFO] [stderr]   36:     0x752bb9ccb834 - <<std[4ece947bc34e96db]::thread::Builder>::spawn_unchecked_<rustc_interface[debe5311a742862e]::util::run_in_thread_with_globals<rustc_interface[debe5311a742862e]::util::run_in_thread_pool_with_globals<rustc_interface[debe5311a742862e]::interface::run_compiler<(), rustc_driver_impl[994997776c209ede]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[bdde32e857371a49]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
[INFO] [stderr]   37:     0x752bb9cccc2b - std::sys::pal::unix::thread::Thread::new::thread_start::hd325dd57d8c72c6b
[INFO] [stderr]   38:     0x752bb3a8aaa4 - <unknown>
[INFO] [stderr]   39:     0x752bb3b17a34 - clone
[INFO] [stderr]   40:                0x0 - <unknown>
[INFO] [stderr] 
[INFO] [stderr] error: the compiler unexpectedly panicked. this is a bug.
[INFO] [stderr] 
[INFO] [stderr] 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
[INFO] [stderr] 
[INFO] [stderr] note: rustc 1.88.0-beta.4 (95597e848 2025-05-25) running on x86_64-unknown-linux-gnu
[INFO] [stderr] 
[INFO] [stderr] note: compiler flags: -C opt-level=2 -C embed-bitcode=no -C debuginfo=2 -C debug-assertions=on
[INFO] [stderr] 
[INFO] [stderr] note: some of the compiler flags provided by cargo are hidden
[INFO] [stderr] 
[INFO] [stderr] query stack during panic:
[INFO] [stderr] #0 [early_lint_checks] perform lints prior to AST lowering
[INFO] [stderr] #1 [hir_crate] getting the crate HIR
[INFO] [stderr] #2 [analysis] running analysis passes on this crate
[INFO] [stderr] end of query stack

[bjorn3]

Likely caused by the #137978 refactorings. cc @nnethercote

[matthiaskrgr]

this is probably #140884 which was fixed via #141318

[apiraino]

I am not clear why I can't reproduce this (cargo +beta build on the mcuboot crate). If it's because the fix #141318 merged ~3 weeks ago in already in the latest beta, why can't I reproduce with the previous 2025-04-13 beta?

[cuviper]

I am not clear why I can't reproduce this (cargo +beta build on the mcuboot crate).

The crater log succeeded at cargo build, but failed at cargo test, and I can reproduce this myself, even just cargo check --tests.

It looks like this just barely snuck into beta. The first 1.88.0-beta.1 is beta-2025-05-09, which does reproduce the assertion. On the nightly side, nightly-2025-05-09 passes and nightly-2025-05-10 fails. Bisected:

searched nightlies: from nightly-2025-05-09 to nightly-2025-05-10
regressed nightly: nightly-2025-05-10
searched commit range: 50aa041...dcecb99
regressed commit: a7b1b24

bisected with cargo-bisect-rustc v0.6.10

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

cargo bisect-rustc --start 2025-05-09 --end 2025-05-10 -- check --tests

And then bisecting for the fix:

searched nightlies: from nightly-2025-05-10 to nightly-2025-06-13
regressed nightly: nightly-2025-05-11
searched commit range: dcecb99...7b84c9e
regressed commit: 7e432c4

bisected with cargo-bisect-rustc v0.6.10

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

cargo bisect-rustc --regress success --start 2025-05-10 -- check --tests

But that just changed it to a debug-assertion -- #141318 is probably still the better fix.