Internal Compiler Error

[swooster]

Code

Although I managed to eliminate all dependencies, this is the smallest I could get the reproduction (my apologies for the size!):

use std::any::Any;

fn main() {
    use_service(make_service());
    let _future = async {};
}

fn make_service() -> impl FooService<Box<dyn Any>, Response: Body> {}

fn use_service<S, R>(_service: S)
where
    S: FooService<R>,
    <S::Response as Body>::Data: Any,
{
}

trait Service<Request> {
    type Response: Body;
}

impl<T, Request> Service<Request> for T {
    type Response = ();
}

trait FooService<Request>: Service<Request> {}

impl<T, Request, Resp> FooService<Request> for T
where
    T: Service<Request, Response = Resp>,
    Resp: Body,
{
}

trait Body {
    type Data;
}

impl<T> Body for T {
    type Data = ();
}

Meta

This first shows up in 1.90.0 (I checked 1.86.0, 1.88.0, 1.89.0, 1.90.0 and 1.91.0; the latter two are broken). Nightly is also broken.

rustc --version --verbose:

rustc 1.90.0 (1159e78c4 2025-09-14)
binary: rustc
commit-hash: 1159e78c4747b02ef996e55082b704c09b970588
commit-date: 2025-09-14
host: x86_64-unknown-linux-gnu
release: 1.90.0
LLVM version: 20.1.8

Error output

error: internal compiler error: unexpected ambiguity: CanonicalQueryInput { canonical: Canonical { value: ParamEnvAnd { param_env: ParamEnv { caller_bounds: [] }, value: AliasTy { args: [Alias(Projection, AliasTy { args: [Alias(Opaque, AliasTy { args: [], def_id: DefId(0:7 ~ min_ice[90f0]::make_service::{opaque#0}), .. }), std::boxed::Box<dyn [Binder { value: Trait(std::any::Any), bound_vars: [] }] + '^0, std::alloc::Global>], def_id: DefId(0:12 ~ min_ice[90f0]::Service::Response), .. })], def_id: DefId(0:24 ~ min_ice[90f0]::Body::Data), .. } }, max_universe: U0, variables: [Region(U0)] }, typing_mode: Analysis { defining_opaque_types_and_generators: [] } } Canonical { value: QueryResponse { var_values: CanonicalVarValues { var_values: ['^0] }, region_constraints: QueryRegionConstraints { outlives: [], assumptions: [] }, certainty: Ambiguous, opaque_types: [], value: NormalizationResult { normalized_ty: ^1 } }, max_universe: U0, variables: [Region(U0), Ty(General(U0))] }
  |
  = note: delayed at compiler/rustc_trait_selection/src/traits/query/normalize.rs:288:30 - disabled backtrace

error: internal compiler error: error performing operation: fully_perform
 --> src/main.rs:4:5
  |
4 |     use_service(make_service());
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
note: delayed at /rustc-dev/1159e78c4747b02ef996e55082b704c09b970588/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs:92:25 - disabled backtrace
 --> src/main.rs:4:5
  |
4 |     use_service(make_service());
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^

Backtrace

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: unexpected ambiguity: CanonicalQueryInput { canonical: Canonical { value: ParamEnvAnd { param_env: ParamEnv { caller_bounds: [] }, value: AliasTy { args: [Alias(Projection, AliasTy { args: [Alias(Opaque, AliasTy { args: [], def_id: DefId(0:7 ~ min_ice[90f0]::make_service::{opaque#0}), .. }), std::boxed::Box<dyn [Binder { value: Trait(std::any::Any), bound_vars: [] }] + '^0, std::alloc::Global>], def_id: DefId(0:12 ~ min_ice[90f0]::Service::Response), .. })], def_id: DefId(0:24 ~ min_ice[90f0]::Body::Data), .. } }, max_universe: U0, variables: [Region(U0)] }, typing_mode: Analysis { defining_opaque_types_and_generators: [] } } Canonical { value: QueryResponse { var_values: CanonicalVarValues { var_values: ['^0] }, region_constraints: QueryRegionConstraints { outlives: [], assumptions: [] }, certainty: Ambiguous, opaque_types: [], value: NormalizationResult { normalized_ty: ^1 } }, max_universe: U0, variables: [Region(U0), Ty(General(U0))] }
  |
  = note: delayed at compiler/rustc_trait_selection/src/traits/query/normalize.rs:288:30
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
             3: <rustc_errors::DiagCtxtHandle>::delayed_bug::<alloc::string::String>
             4: <rustc_trait_selection::traits::query::normalize::QueryNormalizer as rustc_type_ir::fold::FallibleTypeFolder<rustc_middle::ty::context::TyCtxt>>::try_fold_ty
             5: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::generic_args::GenericArg> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection::traits::query::normalize::QueryNormalizer>
             6: rustc_traits::type_op::type_op_normalize_clause
             7: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::type_op_normalize_clause::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
             8: <rustc_query_impl::query_impl::type_op_normalize_clause::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_type_ir::canonical::CanonicalQueryInput<rustc_middle::ty::context::TyCtxt, rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::Normalize<rustc_middle::ty::predicate::Clause>>>)>>::call_once
             9: <rustc_query_system::query::plumbing::execute_job_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_type_ir::canonical::CanonicalQueryInput<rustc_middle::ty::context::TyCtxt, rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::Normalize<rustc_middle::ty::Ty>>>, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#2}::{closure#2} as core::ops::function::FnOnce<((rustc_query_impl::plumbing::QueryCtxt, rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_type_ir::canonical::CanonicalQueryInput<rustc_middle::ty::context::TyCtxt, rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::Normalize<rustc_middle::ty::Ty>>>, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>), rustc_type_ir::canonical::CanonicalQueryInput<rustc_middle::ty::context::TyCtxt, rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::Normalize<rustc_middle::ty::Ty>>>)>>::call_once
            10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_type_ir::canonical::CanonicalQueryInput<rustc_middle::ty::context::TyCtxt, rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::Normalize<rustc_middle::ty::predicate::Clause>>>, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
            11: rustc_query_impl::query_impl::type_op_normalize_clause::get_query_incr::__rust_end_short_backtrace
            12: <rustc_borrowck::type_check::TypeChecker>::normalize_and_prove_instantiated_predicates
            13: <rustc_borrowck::type_check::TypeChecker as rustc_middle::mir::visit::Visitor>::visit_operand
            14: <rustc_borrowck::type_check::TypeChecker as rustc_middle::mir::visit::Visitor>::visit_body
            15: rustc_borrowck::type_check::type_check
            16: rustc_borrowck::do_mir_borrowck
            17: rustc_borrowck::mir_borrowck
            18: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
            19: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
            20: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
            21: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
            22: rustc_interface::passes::analysis
            23: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
            24: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
            25: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
            26: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
            27: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
            28: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            29: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            30: std::sys::pal::unix::thread::Thread::new::thread_start
            31: start_thread
                       at ./nptl/pthread_create.c:442:8
            32: __GI___clone3
                       at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81:0
          

error: internal compiler error: error performing operation: fully_perform
 --> src/main.rs:4:5
  |
4 |     use_service(make_service());
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
note: delayed at /rustc-dev/1159e78c4747b02ef996e55082b704c09b970588/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs:92:25
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_borrowck::type_check::TypeChecker>::normalize_and_prove_instantiated_predicates
         5: <rustc_borrowck::type_check::TypeChecker as rustc_middle::mir::visit::Visitor>::visit_operand
         6: <rustc_borrowck::type_check::TypeChecker as rustc_middle::mir::visit::Visitor>::visit_body
         7: rustc_borrowck::type_check::type_check
         8: rustc_borrowck::do_mir_borrowck
         9: rustc_borrowck::mir_borrowck
        10: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        11: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        12: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
        16: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        17: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
        18: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
        19: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        20: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        21: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        22: std::sys::pal::unix::thread::Thread::new::thread_start
        23: start_thread
                   at ./nptl/pthread_create.c:442:8
        24: __GI___clone3
                   at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81:0
 --> src/main.rs:4:5
  |
4 |     use_service(make_service());
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^

[theemathas]

Bisection result:

searched nightlies: from nightly-2025-06-23 to nightly-2025-08-02
regressed nightly: nightly-2025-07-18
searched commit range: 5795086...e466296
regressed commit: e466296

bisected with cargo-bisect-rustc v0.6.10

Host triple: aarch64-apple-darwin
Reproduce with:

cargo bisect-rustc --start=1.89.0 --end=1.90.0 --regress=ice

cc @compiler-errors (author of #141762)