ICE: `overflow expanding free alias type`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(lazy_type_alias)]
type A = (i32, i32, i32, i32);
type B = (A, A, A, A);
type C = (B, B, B, (B, B, B, B));
type D = (C, C, C, C);

fn foo(x: D) {}

fn main() {}

original:

type A = (i32, i32, i32, i32);
type B = (A, A, A, A);
type C = (B, B, B, (B, B, B, B));
type D = (C, C, C, C);

fn foo(x: D) { //~ NOTE `x` has type `(...
    Some(Some(Some(Some(Some(Some(Some(Some("")))))))); //~ ERROR expected function, found `(...
}

fn main() {}

Version information

rustc 1.89.0-nightly (6c8138de8 2025-06-12)
binary: rustc
commit-hash: 6c8138de8f1c96b2f66adbbc0e37c73525444750
commit-date: 2025-06-12
host: x86_64-unknown-linux-gnu
release: 1.89.0-nightly
LLVM version: 20.1.5

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zcrate-attr=feature(lazy_type_alias)

Program output

warning: the feature `lazy_type_alias` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:12
  |
1 | #![feature(lazy_type_alias)]
  |            ^^^^^^^^^^^^^^^
  |
  = note: see issue #112792 <https://github.com/rust-lang/rust/issues/112792> for more information
  = note: `#[warn(incomplete_features)]` on by default

warning: unused variable: `x`
 --> /tmp/icemaker_global_tempdir.KwqqEbbkwvG6/rustc_testrunner_tmpdir_reporting.KLV1phiERj3d/mvce.rs:6:8
  |
6 | fn foo(x: D) {}
  |        ^ help: if this is intentional, prefix it with an underscore: `_x`
  |
  = note: `#[warn(unused_variables)]` on by default

warning: type alias `A` is never used
 --> /tmp/icemaker_global_tempdir.KwqqEbbkwvG6/rustc_testrunner_tmpdir_reporting.KLV1phiERj3d/mvce.rs:1:6
  |
1 | type A = (i32, i32, i32, i32);
  |      ^
  |
  = note: `#[warn(dead_code)]` on by default

warning: type alias `B` is never used
 --> /tmp/icemaker_global_tempdir.KwqqEbbkwvG6/rustc_testrunner_tmpdir_reporting.KLV1phiERj3d/mvce.rs:2:6
  |
2 | type B = (A, A, A, A);
  |      ^

warning: type alias `C` is never used
 --> /tmp/icemaker_global_tempdir.KwqqEbbkwvG6/rustc_testrunner_tmpdir_reporting.KLV1phiERj3d/mvce.rs:3:6
  |
3 | type C = (B, B, B, (B, B, B, B));
  |      ^

warning: type alias `D` is never used
 --> /tmp/icemaker_global_tempdir.KwqqEbbkwvG6/rustc_testrunner_tmpdir_reporting.KLV1phiERj3d/mvce.rs:4:6
  |
4 | type D = (C, C, C, C);
  |      ^

warning: function `foo` is never used
 --> /tmp/icemaker_global_tempdir.KwqqEbbkwvG6/rustc_testrunner_tmpdir_reporting.KLV1phiERj3d/mvce.rs:6:4
  |
6 | fn foo(x: D) {}
  |    ^^^

warning: 7 warnings emitted

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: overflow expanding free alias type
  |
  = note: delayed at compiler/rustc_middle/src/ty/util.rs:1048:39
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
             3: <rustc_errors::DiagCtxtHandle>::delayed_bug::<&str>
             4: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
             5: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
             6: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
             7: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty::{closure#0}
             8: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
             9: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
            10: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
            11: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
            12: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty::{closure#0}
            13: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
            14: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
            15: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty::{closure#0}
            16: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_fn_ty
            17: rustc_hir_analysis::collect::lower_fn_sig_recovering_infer_ret_ty
            18: rustc_hir_analysis::collect::fn_sig
            19: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::fn_sig::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 24]>>
            20: <rustc_query_impl::query_impl::fn_sig::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
            21: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 24]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            22: rustc_query_impl::query_impl::fn_sig::get_query_non_incr::__rust_end_short_backtrace
            23: rustc_hir_analysis::check::wfcheck::check_item
            24: rustc_hir_analysis::check::wfcheck::check_well_formed
            25: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
            26: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 1]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            27: rustc_query_impl::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
            28: rustc_hir_analysis::check::wfcheck::check_type_wf
            29: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
            30: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            31: rustc_query_impl::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
            32: rustc_hir_analysis::check_crate
            33: rustc_interface::passes::analysis
            34: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
            35: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            36: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
            37: 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}
            38: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
            39: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            40: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            41: std::sys::pal::unix::thread::Thread::new::thread_start
            42: <unknown>
            43: <unknown>
          

error: internal compiler error: overflow expanding free alias type
  |
  = note: delayed at compiler/rustc_middle/src/ty/util.rs:1048:39
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
             3: <rustc_errors::DiagCtxtHandle>::delayed_bug::<&str>
             4: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
             5: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
             6: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
             7: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
             8: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
             9: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty::{closure#0}
            10: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::Ty> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::fold_with::<rustc_middle::ty::util::FreeAliasTypeExpander>
            11: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty.cold
            12: <rustc_middle::ty::util::FreeAliasTypeExpander as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_ty::{closure#0}
            13: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_fn_ty
            14: rustc_hir_analysis::collect::lower_fn_sig_recovering_infer_ret_ty
            15: rustc_hir_analysis::collect::fn_sig
            16: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::fn_sig::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 24]>>
            17: <rustc_query_impl::query_impl::fn_sig::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
            18: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 24]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            19: rustc_query_impl::query_impl::fn_sig::get_query_non_incr::__rust_end_short_backtrace
            20: rustc_hir_analysis::check::wfcheck::check_item
            21: rustc_hir_analysis::check::wfcheck::check_well_formed
            22: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
            23: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 1]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            24: rustc_query_impl::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
            25: rustc_hir_analysis::check::wfcheck::check_type_wf
            26: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
            27: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            28: rustc_query_impl::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
            29: rustc_hir_analysis::check_crate
            30: rustc_interface::passes::analysis
            31: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
            32: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
            33: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
            34: 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}
            35: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
            36: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            37: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            38: std::sys::pal::unix::thread::Thread::new::thread_start
            39: <unknown>
            40: <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 1.89.0-nightly (6c8138de8 2025-06-12) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=feature(lazy_type_alias) -Z dump-mir-dir=dir

query stack during panic:
end of query stack

@rustbot label +F-lazy_type_alias

[matthiaskrgr]

smaller 🤷

#![feature(lazy_type_alias)]
type A = ();
type B = (A, A, A, A);
type C = (B, B, B, B, B, B, B);
type D = (C, C, C, C);
fn foo(x: D) {}
fn main() {}

bisects to nightly-2024-11-25

  commit[0] 2024-11-22: Auto merge of #133339 - jieyouxu:rollup-gav0nvr, r=jieyouxu
  commit[1] 2024-11-22: Auto merge of #133349 - ehuss:stabilize-2024, r=traviscross,compiler-errors
  commit[2] 2024-11-23: Auto merge of #132329 - compiler-errors:fn-and-destruct, r=lcnr
  commit[3] 2024-11-23: Auto merge of #133360 - compiler-errors:rollup-a2o38tq, r=compiler-errors
  commit[4] 2024-11-23: Auto merge of #132915 - veluca93:unsafe-fields, r=jswrenn
  commit[5] 2024-11-23: Auto merge of #132994 - clubby789:cc-bisect, r=Kobzol
  commit[6] 2024-11-23: Auto merge of #133377 - jieyouxu:rollup-n536hzq, r=jieyouxu
  commit[7] 2024-11-23: Auto merge of #133242 - lcnr:questionable-uwu, r=compiler-errors,BoxyUwU
  commit[8] 2024-11-23: Auto merge of #133379 - jieyouxu:rollup-00jxo71, r=jieyouxu
  commit[9] 2024-11-23: Auto merge of #131859 - chriskrycho:update-trpl, r=onur-ozkan
  commit[10] 2024-11-24: Auto merge of #132597 - lukas-code:btree-plug-leak, r=jhpratt
  commit[11] 2024-11-24: Auto merge of #132611 - compiler-errors:async-prelude, r=ibraheemdev
  commit[12] 2024-11-24: Auto merge of #132791 - tyilo:big-file-fail-fast, r=compiler-errors
  commit[13] 2024-11-24: Auto merge of #133415 - matthiaskrgr:rollup-n1ivyd5, r=matthiaskrgr
  commit[14] 2024-11-24: Auto merge of #133068 - jieyouxu:download-rustc-default-only-for-tools, r=clubby789
  commit[15] 2024-11-24: Auto merge of #133423 - jieyouxu:rollup-m3gyoz6, r=jieyouxu

[moxian]

bisects to nightly-2024-11-25

I cannot reproduce?
For me the output of nightly-2024-11-25 and nightly-2024-11-23 (the nightly-2024-11-24 does not exit) is exactly the same (modulo timestamps)

output..

PS H:\work\my\trash\rust-mini\thing> cargo +nightly-2024-11-25 build 2> a.txt
PS H:\work\my\trash\rust-mini\thing> cargo +nightly-2024-11-23 build 2> out-23.txt
PS H:\work\my\trash\rust-mini\thing> cargo +nightly-2024-11-25 build 2> out-25.txt
PS H:\work\my\trash\rust-mini\thing> diff (cat out-23.txt)  (cat out-25.txt)

InputObject
-----------
note: please attach the file at `H:\work\my\trash\rust-mini\thing\rustc-ice-2025-06-15T01_32_39-5660.txt` to your bug …
  process didn't exit successfully: `H:\_sys\rustup\toolchains\nightly-2024-11-25-x86_64-pc-windows-msvc\bin\rustc.exe…
note: please attach the file at `H:\work\my\trash\rust-mini\thing\rustc-ice-2025-06-15T01_32_34-6212.txt` to your bug …
  process didn't exit successfully: `H:\_sys\rustup\toolchains\nightly-2024-11-23-x86_64-pc-windows-msvc\bin\rustc.exe…

PS H:\work\my\trash\rust-mini\thing> cargo +nightly-2024-11-23 build
   Compiling mycrate v0.1.0 (H:\work\my\trash\rust-mini\thing)
warning: the feature `lazy_type_alias` is incomplete and may not be safe to use and/or cause compiler crashes
 --> src\lib.rs:1:12
  |
1 | #![feature(lazy_type_alias)]
  |            ^^^^^^^^^^^^^^^
  |
  = note: see issue #112792 <https://github.com/rust-lang/rust/issues/112792> for more information
  = note: `#[warn(incomplete_features)]` on by default

warning: unused variable: `x`
 --> src\lib.rs:6:8
  |
6 | fn foo(x: D) {}
  |        ^ help: if this is intentional, prefix it with an underscore: `_x`
  |
  = note: `#[warn(unused_variables)]` on by default

warning: type alias `A` is never used
 --> src\lib.rs:2:6
  |
2 | type A = ();
  |      ^
  |
  = note: `#[warn(dead_code)]` on by default

warning: type alias `B` is never used
 --> src\lib.rs:3:6
  |
3 | type B = (A, A, A, A);
  |      ^

warning: type alias `C` is never used
 --> src\lib.rs:4:6
  |
4 | type C = (B, B, B, B, B, B, B);
  |      ^

warning: type alias `D` is never used
 --> src\lib.rs:5:6
  |
5 | type D = (C, C, C, C);
  |      ^

warning: function `foo` is never used
 --> src\lib.rs:6:4
  |
6 | fn foo(x: D) {}
  |    ^^^

warning: function `main` is never used
 --> src\lib.rs:7:4
  |
7 | fn main() {}
  |    ^^^^

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: overflow expanding weak alias type
  |
  = note: delayed at compiler\rustc_middle\src\ty\util.rs:1084:39 - disabled backtrace

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 `H:\work\my\trash\rust-mini\thing\rustc-ice-2025-06-15T01_42_09-17080.txt` to your bug report

note: compiler flags: --crate-type lib -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:
end of query stack
warning: `mycrate` (lib) generated 8 warnings
error: could not compile `mycrate` (lib); 8 warnings emitted

Caused by:
  process didn't exit successfully: `H:\_sys\rustup\toolchains\nightly-2024-11-23-x86_64-pc-windows-msvc\bin\rustc.exe --crate-name mycrate --edition=2018 src\lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=119 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --check-cfg cfg(docsrs) --check-cfg "cfg(feature, values())" -C metadata=1dd29243f942af68 -C extra-filename=-1dd29243f942af68 --out-dir H:\work\my\trash\rust-mini\thing\target\debug\deps -C incremental=H:\work\my\trash\rust-mini\thing\target\debug\incremental -L dependency=H:\work\my\trash\rust-mini\thing\target\debug\deps` (exit code: 101)

For me bisecting the error message points first to #140249 (which is obviously not the root cause);
and then later to nightly-2024-02-22, and most likely #121344

PRs in nightly-2024-02-22:

 - #121345 (Rollup of 8 pull requests) by Nilstrieb
   - #121167 (resolve: Scale back unloading of speculatively loaded crates)
   - #121196 (Always inline check in `assert_unsafe_precondition` with cfg(debug_assertions))
   - #121241 (Implement `NonZero` traits generically.)
   - #121278 (Remove the "codegen" profile from bootstrap)
   - #121286 (Rename `ConstPropLint` to `KnownPanicsLint`)
   - #121291 (target: Revert default to the medium code model on LoongArch targets)
   - #121302 (Remove `RefMutL` hack in `proc_macro::bridge`)
   - #121318 (Trigger `unsafe_code` lint on invocations of `global_asm`)
 - #121356 (Rollup of 7 pull requests) by matthiaskrgr
   - #119203 (Correct the simd_masked_{load,store} intrinsic docs)
   - #121277 (Refactor trait implementations in `core::convert::num`.)
   - #121322 (Don't ICE when hitting overflow limit in fulfillment loop in next solver)
   - #121323 (Don't use raw parameter types in `find_builder_fn`)
   - #121344 (Expand weak alias types before collecting constrained/referenced late bound regions + refactorings)
   - #121350 (Fix stray trait mismatch in `resolve_associated_item` for `AsyncFn`)
   - #121352 (docs: add missing "the" to `str::strip_prefix` doc)
 - #120904 (match lowering: eagerly simplify match pairs) by Nadrieril
 - #121172 (match lowering: simplify empty candidate selection) by Nadrieril
 - #121380 (Update cargo) by weihanglo
 - #120588 (wasm: Store rlib metadata in wasm object files) by alexcrichton
 - #120718 (Add "algebraic" fast-math intrinsics, based on fast-math ops that cannot return poison) by saethlin
 - #121383 (Rollup of 7 pull requests) by Dylan-DPC
   - #121208 (Convert `delayed_bug`s to `bug`s.)
   - #121288 (make rustc_expand translatable)
   - #121304 (Add docs for extension proc-macro)
   - #121328 (Make --verbose imply -Z write-long-types-to-disk=no)
   - #121338 (Downgrade ambiguous_wide_pointer_comparisons suggestions to MaybeIncorrect)
   - #121361 (diagnostic items for legacy numeric modules)
   - #121375 (Print proper relative path for descriptive name check)
 - #121400 (Rollup of 8 pull requests) by fmease
   - #121044 (Support async trait bounds in macros)
   - #121175 (match lowering: test one or pattern at a time)
   - #121340 (bootstrap: apply most of clippy's suggestions)
   - #121347 (compiletest: support auxiliaries with auxiliaries)
   - #121359 (miscellaneous type system improvements)
   - #121366 (Remove `diagnostic_builder.rs`)
   - #121379 (Remove an `unchecked_error_guaranteed` call.)
   - #121396 (make it possible for outside crates to inspect a mir::ConstValue with the interpreter)
 - #121321 (Yeet `QueryTypeRelatingDelegate`, move `NllTypeRelating` into borrowck crate) by compiler-errors
 - #117658 (rename ptr::invalid -> ptr::without_provenance) by RalfJung