Open
Description
This one is a bit special because without coherence, it looks like rustc just hangs and with coherence, we ICE.
Not sure which is better though 😆
Code
#![feature(specialization)]
trait Foo {}
impl Foo for <u16 as Assoc>::Output {}
impl Foo for u32 {}
trait Assoc {
type Output;
}
impl Output for u32 {}
impl Assoc for <u16 as Assoc>::Output {
default type Output = bool;
}Meta
rustc --version --verbose:
rustc 1.80.0-nightly (6e1d94708 2024-05-10)
binary: rustc
commit-hash: 6e1d94708a0a4a35ca7e46c6cac98adf62fe800e
commit-date: 2024-05-10
host: x86_64-unknown-linux-gnu
release: 1.80.0-nightly
LLVM version: 18.1.4
rustc 2.rs -Znext-solver=coherence
Error output
error[E0405]: cannot find trait `Output` in this scope
--> 2.rs:12:6
|
12 | impl Output for u32 {}
| ^^^^^^ not found in this scope
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
--> 2.rs:1:12
|
1 | #![feature(specialization)]
| ^^^^^^^^^^^^^^
|
= note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
= help: consider using `min_specialization` instead, which is more stable and complete
= note: `#[warn(incomplete_features)]` on by default
error[E0601]: `main` function not found in crate `2`
--> 2.rs:15:2
|
15 | }
| ^ consider adding a `main` function to `2.rs`
error[E0119]: conflicting implementations of trait `Foo` for type `<u16 as Assoc>::Output`
--> 2.rs:7:1
|
5 | impl Foo for <u16 as Assoc>::Output {}
| ----------------------------------- first implementation here
6 |
7 | impl Foo for u32 {}
| ^^^^^^^^^^^^^^^^ conflicting implementation for `<u16 as Assoc>::Output`
Backtrace
error: internal compiler error: compiler/rustc_trait_selection/src/traits/select/mod.rs:2484:17: impl DefId(0:9 ~ 2[eac6]::{impl#3}) was matchable against Binder { value: TraitPredicate(<u16 as Assoc>, polarity:Positive), bound_vars: [] } but now is not
thread 'rustc' panicked at compiler/rustc_trait_selection/src/traits/select/mod.rs:2484:17:
Box<dyn Any>
stack backtrace:
0: 0x70d6652fec45 - std::backtrace_rs::backtrace::libunwind::trace::h076b7d335d3f5d8e
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
1: 0x70d6652fec45 - std::backtrace_rs::backtrace::trace_unsynchronized::h690cc670e4b53e26
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
2: 0x70d6652fec45 - std::sys_common::backtrace::_print_fmt::h1c4819ca31a9a7e4
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/sys_common/backtrace.rs:68:5
3: 0x70d6652fec45 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h80477bfb9d3c4c0e
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/sys_common/backtrace.rs:44:22
4: 0x70d66534de0b - core::fmt::rt::Argument::fmt::h15c65d56ade59385
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/core/src/fmt/rt.rs:165:63
5: 0x70d66534de0b - core::fmt::write::haea2d0f40af65206
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/core/src/fmt/mod.rs:1157:21
6: 0x70d6652f398f - std::io::Write::write_fmt::h3669847656ea0615
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/io/mod.rs:1835:15
7: 0x70d6652fea1e - std::sys_common::backtrace::_print::ha73eb023eb111e4d
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/sys_common/backtrace.rs:47:5
8: 0x70d6652fea1e - std::sys_common::backtrace::print::hbff52728084c2b90
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/sys_common/backtrace.rs:34:9
9: 0x70d665301389 - std::panicking::default_hook::{{closure}}::h0d17646ea03cf057
10: 0x70d6653010cd - std::panicking::default_hook::h40601e5e85aa667a
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/panicking.rs:298:9
11: 0x70d661cceab0 - std[420967f48346b39c]::panicking::update_hook::<alloc[478b9a7ca3809208]::boxed::Box<rustc_driver_impl[9e6d636adc327e66]::install_ice_hook::{closure#0}>>::{closure#0}
12: 0x70d665301a86 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hd12a80ecb6b6cfe8
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/alloc/src/boxed.rs:2036:9
13: 0x70d665301a86 - std::panicking::rust_panic_with_hook::h33d302c7fc861cff
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/panicking.rs:799:13
14: 0x70d661cfead4 - std[420967f48346b39c]::panicking::begin_panic::<rustc_errors[45d68b0688aaeb54]::ExplicitBug>::{closure#0}
15: 0x70d661cfb476 - std[420967f48346b39c]::sys_common::backtrace::__rust_end_short_backtrace::<std[420967f48346b39c]::panicking::begin_panic<rustc_errors[45d68b0688aaeb54]::ExplicitBug>::{closure#0}, !>
16: 0x70d661cf6a26 - std[420967f48346b39c]::panicking::begin_panic::<rustc_errors[45d68b0688aaeb54]::ExplicitBug>
17: 0x70d661d07c61 - <rustc_errors[45d68b0688aaeb54]::diagnostic::BugAbort as rustc_errors[45d68b0688aaeb54]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
18: 0x70d6621bee9c - rustc_middle[b29a689460622aa4]::util::bug::opt_span_bug_fmt::<rustc_span[7f36b8f4ab5c669f]::span_encoding::Span>::{closure#0}
19: 0x70d6621a387a - rustc_middle[b29a689460622aa4]::ty::context::tls::with_opt::<rustc_middle[b29a689460622aa4]::util::bug::opt_span_bug_fmt<rustc_span[7f36b8f4ab5c669f]::span_encoding::Span>::{closure#0}, !>::{closure#0}
20: 0x70d6621a371b - rustc_middle[b29a689460622aa4]::ty::context::tls::with_context_opt::<rustc_middle[b29a689460622aa4]::ty::context::tls::with_opt<rustc_middle[b29a689460622aa4]::util::bug::opt_span_bug_fmt<rustc_span[7f36b8f4ab5c669f]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
21: 0x70d660498d20 - rustc_middle[b29a689460622aa4]::util::bug::bug_fmt
22: 0x70d6637ab30e - <rustc_trait_selection[6d54a2dd8c1020d6]::traits::select::SelectionContext>::confirm_candidate
23: 0x70d66356f516 - <rustc_trait_selection[6d54a2dd8c1020d6]::traits::select::SelectionContext>::evaluate_trait_predicate_recursively
24: 0x70d663566dc0 - <rustc_trait_selection[6d54a2dd8c1020d6]::traits::select::SelectionContext>::evaluate_root_obligation
25: 0x70d66356538b - rustc_traits[8c7b2acb6abdc47]::evaluate_obligation::evaluate_obligation
26: 0x70d663564d29 - rustc_query_impl[afd3850f0842b024]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[afd3850f0842b024]::query_impl::evaluate_obligation::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 2usize]>>
27: 0x70d663564292 - rustc_query_system[6b56706b6a133fc0]::query::plumbing::try_execute_query::<rustc_query_impl[afd3850f0842b024]::DynamicConfig<rustc_query_system[6b56706b6a133fc0]::query::caches::DefaultCache<rustc_type_ir[f4c1b7e92dc1a1]::canonical::Canonical<rustc_middle[b29a689460622aa4]::ty::context::TyCtxt, rustc_middle[b29a689460622aa4]::ty::ParamEnvAnd<rustc_middle[b29a689460622aa4]::ty::predicate::Predicate>>, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 2usize]>>, false, false, false>, rustc_query_impl[afd3850f0842b024]::plumbing::QueryCtxt, false>
28: 0x70d663563eda - rustc_query_impl[afd3850f0842b024]::query_impl::evaluate_obligation::get_query_non_incr::__rust_end_short_backtrace
29: 0x70d65fc962fb - <rustc_trait_selection[6d54a2dd8c1020d6]::traits::fulfill::FulfillProcessor as rustc_data_structures[fdcc01f8f4e370e]::obligation_forest::ObligationProcessor>::process_obligation
30: 0x70d66300d6e3 - <rustc_data_structures[fdcc01f8f4e370e]::obligation_forest::ObligationForest<rustc_trait_selection[6d54a2dd8c1020d6]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[6d54a2dd8c1020d6]::traits::fulfill::FulfillProcessor>
31: 0x70d6633f7e7a - <rustc_trait_selection[6d54a2dd8c1020d6]::traits::engine::ObligationCtxt>::assumed_wf_types
32: 0x70d663654ea7 - rustc_hir_analysis[4c558df9982554fc]::check::wfcheck::check_well_formed
33: 0x70d663653b9d - rustc_query_impl[afd3850f0842b024]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[afd3850f0842b024]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 1usize]>>
34: 0x70d663653340 - rustc_query_system[6b56706b6a133fc0]::query::plumbing::try_execute_query::<rustc_query_impl[afd3850f0842b024]::DynamicConfig<rustc_query_system[6b56706b6a133fc0]::query::caches::VecCache<rustc_hir[e33a67695c771d92]::hir_id::OwnerId, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[afd3850f0842b024]::plumbing::QueryCtxt, false>
35: 0x70d6636530bf - rustc_query_impl[afd3850f0842b024]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
36: 0x70d663650ff7 - rustc_hir_analysis[4c558df9982554fc]::check::wfcheck::check_mod_type_wf
37: 0x70d663650e1f - rustc_query_impl[afd3850f0842b024]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[afd3850f0842b024]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 1usize]>>
38: 0x70d663aeda70 - rustc_query_system[6b56706b6a133fc0]::query::plumbing::try_execute_query::<rustc_query_impl[afd3850f0842b024]::DynamicConfig<rustc_query_system[6b56706b6a133fc0]::query::caches::DefaultCache<rustc_span[7f36b8f4ab5c669f]::def_id::LocalModDefId, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[afd3850f0842b024]::plumbing::QueryCtxt, false>
39: 0x70d663aed81b - rustc_query_impl[afd3850f0842b024]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
40: 0x70d66338fc46 - rustc_hir_analysis[4c558df9982554fc]::check_crate
41: 0x70d663385f07 - rustc_interface[d156b119c0ee28cb]::passes::analysis
42: 0x70d663385a55 - rustc_query_impl[afd3850f0842b024]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[afd3850f0842b024]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 1usize]>>
43: 0x70d663dcb565 - rustc_query_system[6b56706b6a133fc0]::query::plumbing::try_execute_query::<rustc_query_impl[afd3850f0842b024]::DynamicConfig<rustc_query_system[6b56706b6a133fc0]::query::caches::SingleCache<rustc_middle[b29a689460622aa4]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[afd3850f0842b024]::plumbing::QueryCtxt, false>
44: 0x70d663dcb2c9 - rustc_query_impl[afd3850f0842b024]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
45: 0x70d663c0324e - rustc_interface[d156b119c0ee28cb]::interface::run_compiler::<core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>, rustc_driver_impl[9e6d636adc327e66]::run_compiler::{closure#0}>::{closure#1}
46: 0x70d663bdfe09 - std[420967f48346b39c]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[d156b119c0ee28cb]::util::run_in_thread_with_globals<rustc_interface[d156b119c0ee28cb]::util::run_in_thread_pool_with_globals<rustc_interface[d156b119c0ee28cb]::interface::run_compiler<core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>, rustc_driver_impl[9e6d636adc327e66]::run_compiler::{closure#0}>::{closure#1}, core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>>::{closure#0}, core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>>
47: 0x70d663bdfbb6 - <<std[420967f48346b39c]::thread::Builder>::spawn_unchecked_<rustc_interface[d156b119c0ee28cb]::util::run_in_thread_with_globals<rustc_interface[d156b119c0ee28cb]::util::run_in_thread_pool_with_globals<rustc_interface[d156b119c0ee28cb]::interface::run_compiler<core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>, rustc_driver_impl[9e6d636adc327e66]::run_compiler::{closure#0}>::{closure#1}, core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>>::{closure#0}, core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[554a336f897370d5]::result::Result<(), rustc_span[7f36b8f4ab5c669f]::ErrorGuaranteed>>::{closure#2} as core[554a336f897370d5]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
48: 0x70d66530b8cb - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h56757e55bbcfa856
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/alloc/src/boxed.rs:2022:9
49: 0x70d66530b8cb - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hf230e264012c630a
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/alloc/src/boxed.rs:2022:9
50: 0x70d66530b8cb - std::sys::pal::unix::thread::Thread::new::thread_start::hfcc46c6a7fe0b042
at /rustc/6e1d94708a0a4a35ca7e46c6cac98adf62fe800e/library/std/src/sys/pal/unix/thread.rs:108:17
51: 0x70d65eaa955a - <unknown>
52: 0x70d65eb26a3c - <unknown>
53: 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 `/tmp/im/rustc-ice-2024-05-11T13_50_03-227107.txt` to your bug report
note: compiler flags: -Z next-solver=coherence
query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `u16: Assoc`
#1 [check_well_formed] checking that `<impl at 2.rs:13:1: 13:38>` is well-formed
#2 [check_mod_type_wf] checking that types are well-formed in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 4 previous errors; 1 warning emitted
Some errors have detailed explanations: E0119, E0405, E0601.
For more information about an error, try `rustc --explain E0119`.