ICE: inference variables in normalized parameter environment: unconstrained type #150091
Description
Code
The only similar issue I found is #120033, but it can no longer trigger the ICE in the latest version of the Rust compiler. I'm not sure if this is a duplicate.
#![feature(sized_hierarchy)]
#![feature(non_lifetime_binders)]
use std::marker::PointeeSized;
pub trait Foo<T: PointeeSized> {
type Bar<K: PointeeSized>: PointeeSized;
}
pub fn f<T1, T2>(a: T1, b: T2)
where
T1: for<K, T> Foo<usize, Bar<K> = T>,
T2: for<K, T> Foo<usize, Bar<K> = <T1 as Foo<usize>>::Bar<T>>,
{
}Meta
rustc --version --verbose:
rustc 1.94.0-nightly (21ff67df1 2025-12-15)
binary: rustc
commit-hash: 21ff67df15329dd7548ccba54b6c6ae9a562124f
commit-date: 2025-12-15
host: x86_64-unknown-linux-gnu
release: 1.94.0-nightly
LLVM version: 21.1.8
Program Output
warning: the feature `non_lifetime_binders` is incomplete and may not be safe to use and/or cause compiler crashes
--> <source>:2:12
|
2 | #![feature(non_lifetime_binders)]
| ^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
= note: `#[warn(incomplete_features)]` on by default
error[E0601]: `main` function not found in crate `example`
--> <source>:15:2
|
15 | }
| ^ consider adding a `main` function to `<source>`
error: internal compiler error: compiler/rustc_trait_selection/src/traits/mod.rs:311:13: inference variables in normalized parameter environment: unconstrained type
--> <source>:10:1
|
10 | / pub fn f<T1, T2>(a: T1, b: T2)
11 | | where
12 | | T1: for<K, T> Foo<usize, Bar<K> = T>,
13 | | T2: for<K, T> Foo<usize, Bar<K> = <T1 as Foo<usize>>::Bar<T>>,
| |__________________________________________________________________^
thread 'rustc' (3) panicked at compiler/rustc_trait_selection/src/traits/mod.rs:311:13:
Box<dyn Any>
stack backtrace:
0: 0x71ded458a253 - <<std[5ec89fed4875b12f]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[26a7a51be8c9f870]::fmt::Display>::fmt
1: 0x71ded4c10708 - core[26a7a51be8c9f870]::fmt::write
2: 0x71ded45a08a6 - <std[5ec89fed4875b12f]::sys::stdio::unix::Stderr as std[5ec89fed4875b12f]::io::Write>::write_fmt
3: 0x71ded4560a18 - std[5ec89fed4875b12f]::panicking::default_hook::{closure#0}
4: 0x71ded457e123 - std[5ec89fed4875b12f]::panicking::default_hook
5: 0x71ded356ffb7 - std[5ec89fed4875b12f]::panicking::update_hook::<alloc[673ccbb8a4c5d329]::boxed::Box<rustc_driver_impl[50f6efb3f18c5e4b]::install_ice_hook::{closure#1}>>::{closure#0}
6: 0x71ded457e402 - std[5ec89fed4875b12f]::panicking::panic_with_hook
7: 0x71ded35ad101 - std[5ec89fed4875b12f]::panicking::begin_panic::<rustc_errors[d468dc7f6b98c50]::ExplicitBug>::{closure#0}
8: 0x71ded359d516 - std[5ec89fed4875b12f]::sys::backtrace::__rust_end_short_backtrace::<std[5ec89fed4875b12f]::panicking::begin_panic<rustc_errors[d468dc7f6b98c50]::ExplicitBug>::{closure#0}, !>
9: 0x71ded359d1af - std[5ec89fed4875b12f]::panicking::begin_panic::<rustc_errors[d468dc7f6b98c50]::ExplicitBug>
10: 0x71ded35ca7f1 - <rustc_errors[d468dc7f6b98c50]::diagnostic::BugAbort as rustc_errors[d468dc7f6b98c50]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
11: 0x71ded3b4a2ec - <rustc_errors[d468dc7f6b98c50]::DiagCtxtHandle>::span_bug::<rustc_span[ae684922c33956fd]::span_encoding::Span, alloc[673ccbb8a4c5d329]::string::String>
12: 0x71ded3b6d6c6 - rustc_middle[7d117b0519601dc6]::util::bug::opt_span_bug_fmt::<rustc_span[ae684922c33956fd]::span_encoding::Span>::{closure#0}
13: 0x71ded3b6d872 - rustc_middle[7d117b0519601dc6]::ty::context::tls::with_opt::<rustc_middle[7d117b0519601dc6]::util::bug::opt_span_bug_fmt<rustc_span[ae684922c33956fd]::span_encoding::Span>::{closure#0}, !>::{closure#0}
14: 0x71ded3b5f04b - rustc_middle[7d117b0519601dc6]::ty::context::tls::with_context_opt::<rustc_middle[7d117b0519601dc6]::ty::context::tls::with_opt<rustc_middle[7d117b0519601dc6]::util::bug::opt_span_bug_fmt<rustc_span[ae684922c33956fd]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
15: 0x71ded230fa78 - rustc_middle[7d117b0519601dc6]::util::bug::span_bug_fmt::<rustc_span[ae684922c33956fd]::span_encoding::Span>
16: 0x71ded55068d2 - rustc_trait_selection[f518b5b75a7ddddf]::traits::do_normalize_predicates
17: 0x71ded53fb05f - rustc_trait_selection[f518b5b75a7ddddf]::traits::normalize_param_env_or_error
18: 0x71ded5400449 - rustc_ty_utils[5e92cc0cb70ef2cf]::ty::param_env
19: 0x71ded53ffecd - rustc_query_impl[27139b72c8912d2b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[27139b72c8912d2b]::query_impl::param_env::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 8usize]>>
20: 0x71ded4c19c86 - rustc_query_system[5d3859f1d59bc7f3]::query::plumbing::try_execute_query::<rustc_query_impl[27139b72c8912d2b]::DynamicConfig<rustc_query_system[5d3859f1d59bc7f3]::query::caches::DefIdCache<rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[27139b72c8912d2b]::plumbing::QueryCtxt, false>
21: 0x71ded4c19771 - rustc_query_impl[27139b72c8912d2b]::query_impl::param_env::get_query_non_incr::__rust_end_short_backtrace
22: 0x71ded54fc7c0 - rustc_hir_analysis[786560d794dfc663]::check::wfcheck::check_item_fn
23: 0x71ded53628dd - rustc_hir_analysis[786560d794dfc663]::check::check::check_item_type
24: 0x71ded535e936 - rustc_hir_analysis[786560d794dfc663]::check::wfcheck::check_well_formed
25: 0x71ded535e917 - rustc_query_impl[27139b72c8912d2b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[27139b72c8912d2b]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 1usize]>>
26: 0x71ded535e18d - rustc_query_system[5d3859f1d59bc7f3]::query::plumbing::try_execute_query::<rustc_query_impl[27139b72c8912d2b]::DynamicConfig<rustc_data_structures[32d4a3d751e78af5]::vec_cache::VecCache<rustc_span[ae684922c33956fd]::def_id::LocalDefId, rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[5d3859f1d59bc7f3]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[27139b72c8912d2b]::plumbing::QueryCtxt, false>
27: 0x71ded535dc96 - rustc_query_impl[27139b72c8912d2b]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
28: 0x71ded535b430 - rustc_hir_analysis[786560d794dfc663]::check::wfcheck::check_type_wf
29: 0x71ded535b321 - rustc_query_impl[27139b72c8912d2b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[27139b72c8912d2b]::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 1usize]>>
30: 0x71ded5dafd54 - rustc_query_system[5d3859f1d59bc7f3]::query::plumbing::try_execute_query::<rustc_query_impl[27139b72c8912d2b]::DynamicConfig<rustc_query_system[5d3859f1d59bc7f3]::query::caches::SingleCache<rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[27139b72c8912d2b]::plumbing::QueryCtxt, false>
31: 0x71ded5dafb36 - rustc_query_impl[27139b72c8912d2b]::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
32: 0x71ded569f834 - rustc_hir_analysis[786560d794dfc663]::check_crate
33: 0x71ded4ea9bdb - rustc_interface[b41716356610a9ea]::passes::analysis
34: 0x71ded4ea9825 - rustc_query_impl[27139b72c8912d2b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[27139b72c8912d2b]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 0usize]>>
35: 0x71ded5db1526 - rustc_query_system[5d3859f1d59bc7f3]::query::plumbing::try_execute_query::<rustc_query_impl[27139b72c8912d2b]::DynamicConfig<rustc_query_system[5d3859f1d59bc7f3]::query::caches::SingleCache<rustc_middle[7d117b0519601dc6]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[27139b72c8912d2b]::plumbing::QueryCtxt, false>
36: 0x71ded5db10f6 - rustc_query_impl[27139b72c8912d2b]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
37: 0x71ded5f5fc51 - <rustc_interface[b41716356610a9ea]::passes::create_and_enter_global_ctxt<core[26a7a51be8c9f870]::option::Option<rustc_interface[b41716356610a9ea]::queries::Linker>, rustc_driver_impl[50f6efb3f18c5e4b]::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core[26a7a51be8c9f870]::ops::function::FnOnce<(&rustc_session[276d18328e744fa4]::session::Session, rustc_middle[7d117b0519601dc6]::ty::context::CurrentGcx, alloc[673ccbb8a4c5d329]::sync::Arc<rustc_data_structures[32d4a3d751e78af5]::jobserver::Proxy>, &std[5ec89fed4875b12f]::sync::once_lock::OnceLock<rustc_middle[7d117b0519601dc6]::ty::context::GlobalCtxt>, &rustc_data_structures[32d4a3d751e78af5]::sync::worker_local::WorkerLocal<rustc_middle[7d117b0519601dc6]::arena::Arena>, &rustc_data_structures[32d4a3d751e78af5]::sync::worker_local::WorkerLocal<rustc_hir[6a9da475a5f9b785]::Arena>, rustc_driver_impl[50f6efb3f18c5e4b]::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
38: 0x71ded5ded2da - rustc_interface[b41716356610a9ea]::interface::run_compiler::<(), rustc_driver_impl[50f6efb3f18c5e4b]::run_compiler::{closure#0}>::{closure#1}
39: 0x71ded5d5f7ce - std[5ec89fed4875b12f]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[b41716356610a9ea]::util::run_in_thread_with_globals<rustc_interface[b41716356610a9ea]::util::run_in_thread_pool_with_globals<rustc_interface[b41716356610a9ea]::interface::run_compiler<(), rustc_driver_impl[50f6efb3f18c5e4b]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
40: 0x71ded5d5f5a0 - <std[5ec89fed4875b12f]::thread::lifecycle::spawn_unchecked<rustc_interface[b41716356610a9ea]::util::run_in_thread_with_globals<rustc_interface[b41716356610a9ea]::util::run_in_thread_pool_with_globals<rustc_interface[b41716356610a9ea]::interface::run_compiler<(), rustc_driver_impl[50f6efb3f18c5e4b]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[26a7a51be8c9f870]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
41: 0x71ded5d5d978 - <std[5ec89fed4875b12f]::sys::thread::unix::Thread>::new::thread_start
42: 0x71decf694ac3 - <unknown>
43: 0x71decf7268c0 - <unknown>
44: 0x0 - <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: please attach the file at `/app/rustc-ice-2025-12-17T11_56_25-1.txt` to your bug report
note: compiler flags: -C debuginfo=2 --crate-type bin -C linker=/opt/compiler-explorer/gcc-15.2.0/bin/gcc
query stack during panic:
#0 [param_env] computing normalized predicates of `f`
#1 [check_well_formed] checking that `f` is well-formed
#2 [check_type_wf] checking that types are well-formed
#3 [analysis] running analysis passes on crate `example`
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted
For more information about this error, try `rustc --explain E0601`.