ICE: cannot relate bound region #144033
Description
auto-reduced (treereduce-rust):
trait FooMut { type Baz: 'static; fn bar<'a, I>(self, iterator: &'a I) where for<'b> &'b I: IntoIterator<Item = &'b &'a Self::Baz>; } struct DelegatingFooMut<T> {} impl<T> FooMut for DelegatingFooMut<T> where T: FooMut, { type Baz = DelegatingBaz<T::Baz>; fn bar<'a, I>(self, collection: &'a I) where for<'b> &'b I: IntoIterator, { let collection = collection.into_iter().map(|b| &b); self.bar(collection) } } struct DelegatingBaz<T>;original:
trait FooMut { type Baz: 'static; fn bar<'a, I>(self, iterator: &'a I) where for<'b> &'b I: IntoIterator<Item = &'b &'a Self::Baz>; } struct DelegatingFooMut<T> where T: FooMut, {} impl<T> FooMut for DelegatingFooMut<T> where T: FooMut, { type Baz = DelegatingBaz<T::Baz>; fn bar<'a, I>(self, collection: &'a I) where for<'b> &'b I: IntoIterator, { let collection = collection.into_iter().map(|b| &b); self.bar(collection) } } struct DelegatingBaz<T>; pub fn main() {}Version information
rustc 1.90.0-nightly (1c6de2150 2025-07-16) binary: rustc commit-hash: 1c6de215099bbe33668de762f9591187f6c25eef commit-date: 2025-07-16 host: x86_64-unknown-linux-gnu release: 1.90.0-nightly LLVM version: 20.1.8 Possibly related line of code:
rust/compiler/rustc_infer/src/infer/region_constraints/mod.rs
Lines 462 to 474 in 1c6de21
Command:
/home/matthias/.rustup/toolchains/master/bin/rustc
Program output
error[E0601]: `main` function not found in crate `mvce` --> /tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs:22:25 | 22 | struct DelegatingBaz<T>; | ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs` error[E0392]: type parameter `T` is never used --> /tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs:7:25 | 7 | struct DelegatingFooMut<T> {} | ^ unused type parameter | = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData` = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead error[E0195]: lifetime parameters do not match the trait definition --> /tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs:14:12 | 14 | fn bar<'a, I>(self, collection: &'a I) | ^^ | = note: lifetime parameters differ in whether they are early- or late-bound note: `'a` differs between the trait and impl --> /tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs:3:12 | 1 | trait FooMut { | ------------ in this trait... 2 | type Baz: 'static; 3 | fn bar<'a, I>(self, iterator: &'a I) | ^^ `'a` is early-bound 4 | where 5 | for<'b> &'b I: IntoIterator<Item = &'b &'a Self::Baz>; | ------------------------ this lifetime bound makes `'a` early-bound ... 9 | / impl<T> FooMut for DelegatingFooMut<T> 10 | | where 11 | | T: FooMut, | |______________- in this impl... ... 14 | fn bar<'a, I>(self, collection: &'a I) | ^^ `'a` is late-bound error[E0392]: type parameter `T` is never used --> /tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs:22:22 | 22 | struct DelegatingBaz<T>; | ^ unused type parameter | = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData` = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead error: internal compiler error: compiler/rustc_infer/src/infer/region_constraints/mod.rs:468:17: cannot relate bound region: '^0.Named(DefId(0:8 ~ mvce[9174]::FooMut::bar::'b)) <= '?5 thread 'rustc' panicked at compiler/rustc_infer/src/infer/region_constraints/mod.rs:468:17: Box<dyn Any> stack backtrace: 0: 0x7b4d45ff9403 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hfecc64209d1f083d 1: 0x7b4d46802877 - core::fmt::write::h2a210ef2ee328422 2: 0x7b4d45feef33 - std::io::Write::write_fmt::h958669e99a2dcc1b 3: 0x7b4d45ff9262 - std::sys::backtrace::BacktraceLock::print::hd76a629e9c354d1a 4: 0x7b4d45ffcd07 - std::panicking::default_hook::{{closure}}::ha5ca805082f016b7 5: 0x7b4d45ffc86b - std::panicking::default_hook::h954991efcc4f3cec 6: 0x7b4d45094523 - std[5063006013ba73a3]::panicking::update_hook::<alloc[31decb083fcbf252]::boxed::Box<rustc_driver_impl[d0e6b8b9dcfdbcef]::install_ice_hook::{closure#1}>>::{closure#0} 7: 0x7b4d45ffd54e - std::panicking::rust_panic_with_hook::h1c54f234944551f2 8: 0x7b4d450ce111 - std[5063006013ba73a3]::panicking::begin_panic::<rustc_errors[f6bd045b92c5704b]::ExplicitBug>::{closure#0} 9: 0x7b4d450c30a6 - std[5063006013ba73a3]::sys::backtrace::__rust_end_short_backtrace::<std[5063006013ba73a3]::panicking::begin_panic<rustc_errors[f6bd045b92c5704b]::ExplicitBug>::{closure#0}, !> 10: 0x7b4d450c2f35 - std[5063006013ba73a3]::panicking::begin_panic::<rustc_errors[f6bd045b92c5704b]::ExplicitBug> 11: 0x7b4d450d7bf1 - <rustc_errors[f6bd045b92c5704b]::diagnostic::BugAbort as rustc_errors[f6bd045b92c5704b]::diagnostic::EmissionGuarantee>::emit_producing_guarantee 12: 0x7b4d4564208c - <rustc_errors[f6bd045b92c5704b]::DiagCtxtHandle>::span_bug::<rustc_span[21ad9ac73572669a]::span_encoding::Span, alloc[31decb083fcbf252]::string::String> 13: 0x7b4d456d65b7 - rustc_middle[2691867c5197ffb4]::util::bug::opt_span_bug_fmt::<rustc_span[21ad9ac73572669a]::span_encoding::Span>::{closure#0} 14: 0x7b4d456b6ada - rustc_middle[2691867c5197ffb4]::ty::context::tls::with_opt::<rustc_middle[2691867c5197ffb4]::util::bug::opt_span_bug_fmt<rustc_span[21ad9ac73572669a]::span_encoding::Span>::{closure#0}, !>::{closure#0} 15: 0x7b4d456b694b - rustc_middle[2691867c5197ffb4]::ty::context::tls::with_context_opt::<rustc_middle[2691867c5197ffb4]::ty::context::tls::with_opt<rustc_middle[2691867c5197ffb4]::util::bug::opt_span_bug_fmt<rustc_span[21ad9ac73572669a]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !> 16: 0x7b4d42d44767 - rustc_middle[2691867c5197ffb4]::util::bug::span_bug_fmt::<rustc_span[21ad9ac73572669a]::span_encoding::Span> 17: 0x7b4d469125f4 - rustc_type_ir[e2a9117d91bef9a6]::relate::structurally_relate_tys::<rustc_middle[2691867c5197ffb4]::ty::context::TyCtxt, rustc_infer[6a9be856b777fd19]::infer::relate::type_relating::TypeRelating>::{closure#0} 18: 0x7b4d46906ea6 - <rustc_infer[6a9be856b777fd19]::infer::relate::type_relating::TypeRelating as rustc_type_ir[e2a9117d91bef9a6]::relate::TypeRelation<rustc_middle[2691867c5197ffb4]::ty::context::TyCtxt>>::tys 19: 0x7b4d46fce23b - <rustc_trait_selection[b677d31ba289951a]::traits::engine::ObligationCtxt>::eq::<rustc_middle[2691867c5197ffb4]::ty::Ty> 20: 0x7b4d45e6d9be - <rustc_trait_selection[b677d31ba289951a]::error_reporting::TypeErrCtxt>::point_at_chain::<rustc_span[21ad9ac73572669a]::ErrorGuaranteed> 21: 0x7b4d45e6ab1b - <rustc_trait_selection[b677d31ba289951a]::error_reporting::TypeErrCtxt>::note_function_argument_obligation::<rustc_span[21ad9ac73572669a]::ErrorGuaranteed> 22: 0x7b4d45e60567 - <rustc_trait_selection[b677d31ba289951a]::error_reporting::TypeErrCtxt>::note_obligation_cause_code::<rustc_span[21ad9ac73572669a]::ErrorGuaranteed, rustc_middle[2691867c5197ffb4]::ty::predicate::Predicate> 23: 0x7b4d45e2a0d5 - <rustc_trait_selection[b677d31ba289951a]::error_reporting::TypeErrCtxt>::note_obligation_cause 24: 0x7b4d45e7892d - <rustc_trait_selection[b677d31ba289951a]::error_reporting::TypeErrCtxt>::report_fulfillment_errors 25: 0x7b4d46a99f41 - <rustc_hir_typeck[265d0d08d07618d]::fn_ctxt::FnCtxt>::try_structurally_resolve_type 26: 0x7b4d47566610 - <rustc_hir_typeck[265d0d08d07618d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args 27: 0x7b4d4755f7ab - <rustc_hir_typeck[265d0d08d07618d]::fn_ctxt::FnCtxt>::check_argument_types 28: 0x7b4d47568e78 - <rustc_hir_typeck[265d0d08d07618d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args 29: 0x7b4d4754d54c - <rustc_hir_typeck[265d0d08d07618d]::fn_ctxt::FnCtxt>::check_expr_block 30: 0x7b4d4756793b - <rustc_hir_typeck[265d0d08d07618d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args 31: 0x7b4d475583bb - rustc_hir_typeck[265d0d08d07618d]::check::check_fn 32: 0x7b4d47a3f1b7 - rustc_hir_typeck[265d0d08d07618d]::typeck_with_inspect::{closure#0} 33: 0x7b4d47a2bbb0 - rustc_query_impl[876323bf6c893e3a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[876323bf6c893e3a]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2691867c5197ffb4]::query::erase::Erased<[u8; 8usize]>> 34: 0x7b4d46a50e2e - rustc_query_system[5227141d7cc7c8f2]::query::plumbing::try_execute_query::<rustc_query_impl[876323bf6c893e3a]::DynamicConfig<rustc_data_structures[cbda6e031a2b752d]::vec_cache::VecCache<rustc_span[21ad9ac73572669a]::def_id::LocalDefId, rustc_middle[2691867c5197ffb4]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[5227141d7cc7c8f2]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[876323bf6c893e3a]::plumbing::QueryCtxt, false> 35: 0x7b4d46a507c9 - rustc_query_impl[876323bf6c893e3a]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace 36: 0x7b4d46df94db - rustc_hir_analysis[ebd647d899a7c63b]::check_crate 37: 0x7b4d471f431d - rustc_interface[f65689421b54b96b]::passes::analysis 38: 0x7b4d471f3f2f - rustc_query_impl[876323bf6c893e3a]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[876323bf6c893e3a]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[2691867c5197ffb4]::query::erase::Erased<[u8; 0usize]>> 39: 0x7b4d478a117c - rustc_query_system[5227141d7cc7c8f2]::query::plumbing::try_execute_query::<rustc_query_impl[876323bf6c893e3a]::DynamicConfig<rustc_query_system[5227141d7cc7c8f2]::query::caches::SingleCache<rustc_middle[2691867c5197ffb4]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[876323bf6c893e3a]::plumbing::QueryCtxt, false> 40: 0x7b4d478a0d44 - rustc_query_impl[876323bf6c893e3a]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace 41: 0x7b4d47b136cb - rustc_interface[f65689421b54b96b]::passes::create_and_enter_global_ctxt::<core[1f172d27a6a395fa]::option::Option<rustc_interface[f65689421b54b96b]::queries::Linker>, rustc_driver_impl[d0e6b8b9dcfdbcef]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0} 42: 0x7b4d47b01594 - rustc_interface[f65689421b54b96b]::interface::run_compiler::<(), rustc_driver_impl[d0e6b8b9dcfdbcef]::run_compiler::{closure#0}>::{closure#1} 43: 0x7b4d479d77f8 - std[5063006013ba73a3]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[f65689421b54b96b]::util::run_in_thread_with_globals<rustc_interface[f65689421b54b96b]::util::run_in_thread_pool_with_globals<rustc_interface[f65689421b54b96b]::interface::run_compiler<(), rustc_driver_impl[d0e6b8b9dcfdbcef]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()> 44: 0x7b4d479d74d6 - <<std[5063006013ba73a3]::thread::Builder>::spawn_unchecked_<rustc_interface[f65689421b54b96b]::util::run_in_thread_with_globals<rustc_interface[f65689421b54b96b]::util::run_in_thread_pool_with_globals<rustc_interface[f65689421b54b96b]::interface::run_compiler<(), rustc_driver_impl[d0e6b8b9dcfdbcef]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[1f172d27a6a395fa]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 45: 0x7b4d479dd57d - std::sys::pal::unix::thread::Thread::new::thread_start::he4bc8e8616f31d56 46: 0x7b4d412a57eb - <unknown> 47: 0x7b4d4132918c - <unknown> 48: 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: rustc 1.90.0-nightly (1c6de2150 2025-07-16) running on x86_64-unknown-linux-gnu query stack during panic: #0 [typeck] type-checking `<impl at /tmp/icemaker_global_tempdir.TMRK74peGta5/rustc_testrunner_tmpdir_reporting.ceno8eeAjDuO/mvce.rs:9:1: 11:15>::bar` #1 [analysis] running analysis passes on this crate end of query stack error: aborting due to 5 previous errors Some errors have detailed explanations: E0195, E0392, E0601. For more information about an error, try `rustc --explain E0195`.