Closed
Description
Code
trait Output<T> {
type Output;
}
trait X {
fn a() -> impl Sized<(), Output = impl Sized<Vec<[u8]>>>;
fn a() -> impl Sized<(), Output = impl Sized<Vec<[u8]>>>;
fn a() -> impl Sized<(), Display = impl Sized<Output<u8>>>;
}
fn main() {}Meta
rustc --version --verbose:
rustc 1.90.0-nightly (6b3ae3f6e 2025-07-09)
binary: rustc
commit-hash: 6b3ae3f6e45a33c2d95fa0362c9b2593e567fd34
commit-date: 2025-07-09
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.7
Error output
error[E0428]: the name `a` is defined multiple times
--> a.rs:9:5
|
7 | fn a() -> impl Sized<(), Output = impl Sized<Vec<[u8]>>>;
| --------------------------------------------------------- previous definition of the value `a` here
8 |
9 | fn a() -> impl Sized<(), Output = impl Sized<Vec<[u8]>>>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `a` redefined here
|
= note: `a` must be defined only once in the value namespace of this trait
error[E0428]: the name `a` is defined multiple times
--> a.rs:11:5
|
7 | fn a() -> impl Sized<(), Output = impl Sized<Vec<[u8]>>>;
| --------------------------------------------------------- previous definition of the value `a` here
...
11 | fn a() -> impl Sized<(), Display = impl Sized<Output<u8>>>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `a` redefined here
|
= note: `a` must be defined only once in the value namespace of this trait
Backtrace
thread 'rustc' panicked at compiler/rustc_hir/src/definitions.rs:70:13:
found DefPathHash collision between DefPath {
data: [
DisambiguatedDefPathData {
data: TypeNs(
"X",
),
disambiguator: 0,
},
DisambiguatedDefPathData {
data: AnonAssocTy(
"a",
),
disambiguator: 3,
},
],
krate: crate0,
} and DefPath {
data: [
DisambiguatedDefPathData {
data: TypeNs(
"X",
),
disambiguator: 0,
},
DisambiguatedDefPathData {
data: AnonAssocTy(
"a",
),
disambiguator: 3,
},
],
krate: crate0,
}. Compilation cannot continue.
stack backtrace:
0: 0x7543cc9af6f3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h8ccd6d637109b1d3
1: 0x7543cd2025f7 - core::fmt::write::hc53026627f361f4c
2: 0x7543cc9a5223 - std::io::Write::write_fmt::he0604e7c2e9707b7
3: 0x7543cc9af552 - std::sys::backtrace::BacktraceLock::print::h3189b00c9fe2c48c
4: 0x7543cc9b2ff7 - std::panicking::default_hook::{{closure}}::h534f1f9ab42146dc
5: 0x7543cc9b2b5b - std::panicking::default_hook::h0285f28ab2202ac2
6: 0x7543cba51393 - std[26476b4b5e24f03f]::panicking::update_hook::<alloc[349ed8f87288922e]::boxed::Box<rustc_driver_impl[a26212666416ae3c]::install_ice_hook::{closure#1}>>::{closure#0}
7: 0x7543cc9b383b - std::panicking::rust_panic_with_hook::hceb7d360e287ad47
8: 0x7543cc9b353a - std::panicking::begin_panic_handler::{{closure}}::h977564ccd46b86ab
9: 0x7543cc9afbc9 - std::sys::backtrace::__rust_end_short_backtrace::h68051c399ed9ae5d
10: 0x7543cc9b321d - __rustc[365f28b82031a682]::rust_begin_unwind
11: 0x7543c90e07d0 - core::panicking::panic_fmt::heb2d3b3aec3bb6b8
12: 0x7543cd95a1ef - <rustc_middle[e68d91ead2495186]::ty::context::TyCtxt>::create_def
13: 0x7543cd9564e8 - <rustc_middle[e68d91ead2495186]::query::plumbing::TyCtxtAt>::create_def
14: 0x7543cc8f6c03 - rustc_ty_utils[d2e8b753067980c7]::assoc::associated_type_for_impl_trait_in_trait
15: 0x7543cc8f6943 - <rustc_ty_utils[d2e8b753067980c7]::assoc::RPITVisitor as rustc_hir[27857c4ec092326d]::intravisit::Visitor>::visit_opaque_ty
16: 0x7543cdcb54ec - rustc_ty_utils[d2e8b753067980c7]::assoc::associated_types_for_impl_traits_in_associated_fn
17: 0x7543cdcb4eec - rustc_query_impl[8ffce37a6b3e6334]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_types_for_impl_traits_in_associated_fn::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 16usize]>>
18: 0x7543cdcb4eb7 - <rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_types_for_impl_traits_in_associated_fn::dynamic_query::{closure#2} as core[a0c6e5e304bc8aad]::ops::function::FnOnce<(rustc_middle[e68d91ead2495186]::ty::context::TyCtxt, rustc_span[baae63ed02fe6a15]::def_id::DefId)>>::call_once
19: 0x7543cd3779fb - rustc_query_system[8d81dc6dab7459d8]::query::plumbing::try_execute_query::<rustc_query_impl[8ffce37a6b3e6334]::DynamicConfig<rustc_query_system[8d81dc6dab7459d8]::query::caches::DefIdCache<rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[8ffce37a6b3e6334]::plumbing::QueryCtxt, false>
20: 0x7543cd377228 - rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_types_for_impl_traits_in_associated_fn::get_query_non_incr::__rust_end_short_backtrace
21: 0x7543ce3261f6 - <core[a0c6e5e304bc8aad]::iter::adapters::GenericShunt<core[a0c6e5e304bc8aad]::iter::adapters::map::Map<core[a0c6e5e304bc8aad]::iter::adapters::chain::Chain<core[a0c6e5e304bc8aad]::iter::adapters::map::Map<core[a0c6e5e304bc8aad]::slice::iter::Iter<rustc_hir[27857c4ec092326d]::hir::TraitItemRef>, rustc_ty_utils[d2e8b753067980c7]::assoc::associated_item_def_ids::{closure#0}>, core[a0c6e5e304bc8aad]::iter::adapters::copied::Copied<core[a0c6e5e304bc8aad]::iter::adapters::flatten::FlatMap<core[a0c6e5e304bc8aad]::iter::adapters::filter::Filter<core[a0c6e5e304bc8aad]::slice::iter::Iter<rustc_hir[27857c4ec092326d]::hir::TraitItemRef>, rustc_ty_utils[d2e8b753067980c7]::assoc::associated_item_def_ids::{closure#1}>, &[rustc_span[baae63ed02fe6a15]::def_id::DefId], rustc_ty_utils[d2e8b753067980c7]::assoc::associated_item_def_ids::{closure#2}>>>, core[a0c6e5e304bc8aad]::result::Result<rustc_span[baae63ed02fe6a15]::def_id::DefId, !>::Ok>, core[a0c6e5e304bc8aad]::result::Result<core[a0c6e5e304bc8aad]::convert::Infallible, !>> as core[a0c6e5e304bc8aad]::iter::traits::iterator::Iterator>::next
22: 0x7543ce325efc - rustc_arena[5fe13a6180bd3d26]::outline::<<rustc_arena[5fe13a6180bd3d26]::DroplessArena>::alloc_from_iter<rustc_span[baae63ed02fe6a15]::def_id::DefId, core[a0c6e5e304bc8aad]::iter::adapters::chain::Chain<core[a0c6e5e304bc8aad]::iter::adapters::map::Map<core[a0c6e5e304bc8aad]::slice::iter::Iter<rustc_hir[27857c4ec092326d]::hir::TraitItemRef>, rustc_ty_utils[d2e8b753067980c7]::assoc::associated_item_def_ids::{closure#0}>, core[a0c6e5e304bc8aad]::iter::adapters::copied::Copied<core[a0c6e5e304bc8aad]::iter::adapters::flatten::FlatMap<core[a0c6e5e304bc8aad]::iter::adapters::filter::Filter<core[a0c6e5e304bc8aad]::slice::iter::Iter<rustc_hir[27857c4ec092326d]::hir::TraitItemRef>, rustc_ty_utils[d2e8b753067980c7]::assoc::associated_item_def_ids::{closure#1}>, &[rustc_span[baae63ed02fe6a15]::def_id::DefId], rustc_ty_utils[d2e8b753067980c7]::assoc::associated_item_def_ids::{closure#2}>>>>::{closure#0}, &mut [rustc_span[baae63ed02fe6a15]::def_id::DefId]>
23: 0x7543cd37709f - rustc_query_impl[8ffce37a6b3e6334]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_item_def_ids::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 16usize]>>
24: 0x7543cd376e27 - <rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_item_def_ids::dynamic_query::{closure#2} as core[a0c6e5e304bc8aad]::ops::function::FnOnce<(rustc_middle[e68d91ead2495186]::ty::context::TyCtxt, rustc_span[baae63ed02fe6a15]::def_id::DefId)>>::call_once
25: 0x7543cd3779fb - rustc_query_system[8d81dc6dab7459d8]::query::plumbing::try_execute_query::<rustc_query_impl[8ffce37a6b3e6334]::DynamicConfig<rustc_query_system[8d81dc6dab7459d8]::query::caches::DefIdCache<rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[8ffce37a6b3e6334]::plumbing::QueryCtxt, false>
26: 0x7543cd37749e - rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_item_def_ids::get_query_non_incr::__rust_end_short_backtrace
27: 0x7543cd38d1f7 - rustc_ty_utils[d2e8b753067980c7]::assoc::associated_items
28: 0x7543cd38ce8c - rustc_query_impl[8ffce37a6b3e6334]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_items::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 8usize]>>
29: 0x7543cd216ee5 - rustc_query_system[8d81dc6dab7459d8]::query::plumbing::try_execute_query::<rustc_query_impl[8ffce37a6b3e6334]::DynamicConfig<rustc_query_system[8d81dc6dab7459d8]::query::caches::DefIdCache<rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[8ffce37a6b3e6334]::plumbing::QueryCtxt, false>
30: 0x7543cd216321 - rustc_query_impl[8ffce37a6b3e6334]::query_impl::associated_items::get_query_non_incr::__rust_end_short_backtrace
31: 0x7543cdaba8b0 - rustc_hir_analysis[5870297b7aedcd8f]::check::check::check_item_type
32: 0x7543cdaafd35 - rustc_hir_analysis[5870297b7aedcd8f]::check::wfcheck::check_well_formed
33: 0x7543cdaafd17 - rustc_query_impl[8ffce37a6b3e6334]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8ffce37a6b3e6334]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 1usize]>>
34: 0x7543cdaaf54c - rustc_query_system[8d81dc6dab7459d8]::query::plumbing::try_execute_query::<rustc_query_impl[8ffce37a6b3e6334]::DynamicConfig<rustc_data_structures[33b9671b136d4fc7]::vec_cache::VecCache<rustc_span[baae63ed02fe6a15]::def_id::LocalDefId, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[8d81dc6dab7459d8]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[8ffce37a6b3e6334]::plumbing::QueryCtxt, false>
35: 0x7543cdaaf082 - rustc_query_impl[8ffce37a6b3e6334]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
36: 0x7543cdaab2a4 - rustc_hir_analysis[5870297b7aedcd8f]::check::wfcheck::check_type_wf
37: 0x7543cdaab1b3 - rustc_query_impl[8ffce37a6b3e6334]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8ffce37a6b3e6334]::query_impl::check_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 1usize]>>
38: 0x7543ce2bfe3c - rustc_query_system[8d81dc6dab7459d8]::query::plumbing::try_execute_query::<rustc_query_impl[8ffce37a6b3e6334]::DynamicConfig<rustc_query_system[8d81dc6dab7459d8]::query::caches::SingleCache<rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[8ffce37a6b3e6334]::plumbing::QueryCtxt, false>
39: 0x7543ce2bfc36 - rustc_query_impl[8ffce37a6b3e6334]::query_impl::check_type_wf::get_query_non_incr::__rust_end_short_backtrace
40: 0x7543cd9a71e0 - rustc_hir_analysis[5870297b7aedcd8f]::check_crate
41: 0x7543cdb3a5a3 - rustc_interface[755e80e928d14199]::passes::analysis
42: 0x7543cdb3a1b5 - rustc_query_impl[8ffce37a6b3e6334]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8ffce37a6b3e6334]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 0usize]>>
43: 0x7543ce2c15bc - rustc_query_system[8d81dc6dab7459d8]::query::plumbing::try_execute_query::<rustc_query_impl[8ffce37a6b3e6334]::DynamicConfig<rustc_query_system[8d81dc6dab7459d8]::query::caches::SingleCache<rustc_middle[e68d91ead2495186]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[8ffce37a6b3e6334]::plumbing::QueryCtxt, false>
44: 0x7543ce2c1186 - rustc_query_impl[8ffce37a6b3e6334]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
45: 0x7543ce4fab96 - rustc_interface[755e80e928d14199]::passes::create_and_enter_global_ctxt::<core[a0c6e5e304bc8aad]::option::Option<rustc_interface[755e80e928d14199]::queries::Linker>, rustc_driver_impl[a26212666416ae3c]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
46: 0x7543ce51a657 - rustc_interface[755e80e928d14199]::interface::run_compiler::<(), rustc_driver_impl[a26212666416ae3c]::run_compiler::{closure#0}>::{closure#1}
47: 0x7543ce3ed8b8 - std[26476b4b5e24f03f]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[755e80e928d14199]::util::run_in_thread_with_globals<rustc_interface[755e80e928d14199]::util::run_in_thread_pool_with_globals<rustc_interface[755e80e928d14199]::interface::run_compiler<(), rustc_driver_impl[a26212666416ae3c]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
48: 0x7543ce3ed596 - <<std[26476b4b5e24f03f]::thread::Builder>::spawn_unchecked_<rustc_interface[755e80e928d14199]::util::run_in_thread_with_globals<rustc_interface[755e80e928d14199]::util::run_in_thread_pool_with_globals<rustc_interface[755e80e928d14199]::interface::run_compiler<(), rustc_driver_impl[a26212666416ae3c]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[a0c6e5e304bc8aad]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
49: 0x7543ce3f34bd - std::sys::pal::unix::thread::Thread::new::thread_start::h73b3408c330049d3
50: 0x7543c7ca57eb - <unknown>
51: 0x7543c7d2918c - <unknown>
52: 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: please make sure that you have updated to the latest nightly
note: please attach the file at `/tmp/im/rustc-ice-2025-07-09T16_45_12-2537805.txt` to your bug report
query stack during panic: