Closed
Description
I noticed that my crate https://github.com/tavianator/acap doesn't build with the latest nightly. Here's a reduced testcase:
Code
pub trait Value: PartialOrd {}
impl<T: PartialOrd> Value for T {}
pub trait Distance
where
Self: PartialOrd<<Self as Distance>::Value>,
Self: PartialOrd,
{
type Value: Value;
}
impl<T: Value> Distance for T {
type Value = T;
}
pub trait Proximity<T = Self> {
type Distance: Distance;
}
pub type DistanceValue<K, V = K> = <<K as Proximity<V>>::Distance as Distance>::Value;
struct VpNode<T, R = DistanceValue<T>> {
item: T,
radius: R,
}Meta
rustc --version --verbose:
rustc 1.49.0-nightly (98edd1fbf 2020-10-06)
binary: rustc
commit-hash: 98edd1fbf8a68977a2a7c1312eb1ebff80515a92
commit-date: 2020-10-06
host: x86_64-unknown-linux-gnu
release: 1.49.0-nightly
LLVM version: 11.0
Error output
error: internal compiler error: compiler/rustc_trait_selection/src/traits/select/confirmation.rs:158:25: Projection bound `Binder(<<Self as Proximity<T>>::Distance as std::cmp::PartialOrd<<<Self as Proximity<T>>::Distance as Distance>::Value>>)` was applicable to `Obligation(predicate=Binder(TraitPredicate(<<Self as Proximity<T>>::Distance as std::cmp::PartialOrd>)), depth=0)` but now is not
Backtrace
error: internal compiler error: compiler/rustc_trait_selection/src/traits/select/confirmation.rs:158:25: Projection bound `Binder(<<Self as Proximity<T>>::Distance as std::cmp::PartialOrd<<<Self as Proximity<T>>::Distance as Distance>::Value>>)` was applicable to `Obligation(predicate=Binder(TraitPredicate(<<Self as Proximity<T>>::Distance as std::cmp::PartialOrd>)), depth=0)` but now is not
thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9
stack backtrace:
0: std::panicking::begin_panic
1: rustc_errors::HandlerInner::bug
2: rustc_errors::Handler::bug
3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
4: rustc_middle::ty::context::tls::with_opt::{{closure}}
5: rustc_middle::ty::context::tls::with_opt
6: rustc_middle::util::bug::opt_span_bug_fmt
7: rustc_middle::util::bug::bug_fmt
8: rustc_trait_selection::traits::select::confirmation::<impl rustc_trait_selection::traits::select::SelectionContext>::confirm_projection_candidate::{{closure}}::{{closure}}
9: rustc_infer::infer::InferCtxt::commit_unconditionally
10: rustc_trait_selection::traits::select::confirmation::<impl rustc_trait_selection::traits::select::SelectionContext>::confirm_candidate
11: rustc_trait_selection::traits::select::SelectionContext::select
12: rustc_trait_selection::traits::fulfill::FulfillProcessor::process_trait_obligation
13: rustc_trait_selection::traits::fulfill::FulfillProcessor::progress_changed_obligations
14: rustc_data_structures::obligation_forest::ObligationForest<O>::process_obligations
15: <rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::select_where_possible
16: <rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::select_all_or_error
17: rustc_typeck::check::fn_ctxt::FnCtxt::select_all_obligations_or_error
18: rustc_infer::infer::InferCtxtBuilder::enter
19: rustc_typeck::check::wfcheck::check_associated_item
20: rustc_typeck::check::wfcheck::check_trait_item
21: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::check_trait_item_well_formed>::compute
22: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
23: rustc_data_structures::stack::ensure_sufficient_stack
24: rustc_query_system::query::plumbing::get_query_impl
25: rustc_query_system::query::plumbing::ensure_query_impl
26: rustc_data_structures::sync::par_for_each_in
27: rustc_typeck::check::check::check_wf_new
28: rustc_typeck::check_crate
29: rustc_interface::passes::analysis
30: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
32: rustc_data_structures::stack::ensure_sufficient_stack
33: rustc_query_system::query::plumbing::get_query_impl
34: rustc_interface::passes::QueryContext::enter
35: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
36: rustc_span::with_source_map
37: rustc_interface::interface::create_compiler_and_run
38: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
note: 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: rustc 1.49.0-nightly (98edd1fbf 2020-10-06) running on x86_64-unknown-linux-gnu
query stack during panic:
#0 [check_trait_item_well_formed] checking that `Proximity::Distance` is well-formed
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error
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Area: Associated items (types, constants & functions)Category: This is a bug.Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️Critical priorityRelevant to the compiler team, which will review and decide on the PR/issue.Performance or correctness regression from stable to nightly.