ICE TAIT: Failed to unify obligation; no errors encountered even though `delay_span_bug` issued #111470

VictorBulba · 2023-05-11T15:46:02Z

Hey! I was trying to make it work somehow with impl Fn*, when the function depends on the other generic parameters. I came to this approach and encountered an ICE.

https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=ff6eed88b2feb32c9fb18a94384dc2ca

Code

#![feature(type_alias_impl_trait)]

use std::fmt::Debug;
use std::marker::PhantomData;

struct Foo<T: Debug, F: FnOnce(T)> {
    f: F,
    _phantom: PhantomData<T>,
}

type ImplT = impl Debug;
type FooImpl = Foo<ImplT, impl FnOnce(ImplT)>;

fn bar() -> FooImpl {
    Foo::<i32, _> {
        f: |_| (),
        _phantom: PhantomData,
    }
}

Error output

Output

error: internal compiler error: no errors encountered even though `delay_span_bug` issued

error: internal compiler error: Failed to unify obligation `Obligation(predicate=AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (ImplT,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, depth=0)` with poly_projection `Binder(ProjectionPredicate(AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (i32,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, Term::Ty(())), [])`: Sorts(ExpectedFound { expected: i32, found: ImplT })
  --> src/lib.rs:17:13
   |
17 | fn bar() -> FooImpl {
   |             ^^^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
              2: <rustc_middle::ty::context::TyCtxt>::ty_error_with_message::<rustc_span::span_encoding::Span>
              3: rustc_trait_selection::traits::project::confirm_param_env_candidate
              4: rustc_trait_selection::traits::project::opt_normalize_projection_type
              5: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_trait_selection::traits::project::ProjectAndUnifyResult, rustc_infer::traits::project::MismatchedProjectionTypes, rustc_trait_selection::traits::project::poly_project_and_unify_type::{closure#0}>
              6: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
              7: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
              8: <rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::select_where_possible
              9: <rustc_hir_typeck::fn_ctxt::FnCtxt>::try_coerce
             10: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_return_expr
             11: rustc_hir_typeck::check::check_fn
             12: rustc_hir_typeck::typeck
             13: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::typeck, rustc_query_impl::plumbing::QueryCtxt>
             14: rustc_query_impl::get_query::typeck
             15: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::VecCache<rustc_hir::hir_id::OwnerId, rustc_middle::query::erase::Erased<[u8; 8]>>>
             16: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>::check
             17: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_nested_item
             18: rustc_hir::intravisit::walk_mod::<rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>
             19: rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait
             20: rustc_hir_analysis::collect::type_of::type_of
             21: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt>
             22: rustc_query_impl::get_query::type_of
             23: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
             24: rustc_hir_analysis::check::check::check_mod_item_types
             25: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             26: rustc_query_impl::get_query::check_mod_item_types
             27: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             28: <rustc_session::session::Session>::time::<(), rustc_hir_analysis::check_crate::{closure#6}>
             29: rustc_hir_analysis::check_crate
             30: rustc_interface::passes::analysis
             31: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             32: rustc_query_impl::get_query::analysis
             33: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             34: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
             35: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             36: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             37: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             38: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             39: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/std/src/sys/unix/thread.rs:108:17
             40: start_thread
             41: clone
           

error: internal compiler error: Failed to unify obligation `Obligation(predicate=AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (ImplT,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, depth=0)` with poly_projection `Binder(ProjectionPredicate(AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (i32,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, Term::Ty(())), [])`: Sorts(ExpectedFound { expected: i32, found: ImplT })
  |
  = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
             1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
             2: <rustc_middle::ty::context::TyCtxt>::ty_error_with_message::<rustc_span::span_encoding::Span>
             3: rustc_trait_selection::traits::project::confirm_param_env_candidate
             4: rustc_trait_selection::traits::project::opt_normalize_projection_type
             5: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_trait_selection::traits::project::ProjectAndUnifyResult, rustc_infer::traits::project::MismatchedProjectionTypes, rustc_trait_selection::traits::project::poly_project_and_unify_type::{closure#0}>
             6: <rustc_trait_selection::traits::select::SelectionContext>::evaluate_predicate_recursively
             7: rustc_traits::evaluate_obligation::evaluate_obligation
             8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::evaluate_obligation, rustc_query_impl::plumbing::QueryCtxt>
             9: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::predicate_must_hold_considering_regions
            10: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
            11: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
            12: <rustc_trait_selection::traits::engine::ObligationCtxt>::select_all_or_error
            13: rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints::<rustc_borrowck::type_check::InstantiateOpaqueType, (), <rustc_borrowck::type_check::InstantiateOpaqueType as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform::{closure#0}>
            14: <rustc_borrowck::type_check::TypeChecker>::fully_perform_op::<(), rustc_borrowck::type_check::InstantiateOpaqueType>
            15: <rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>::relate_opaques
            16: <rustc_middle::ty::subst::GenericArg as rustc_middle::ty::relate::Relate>::relate::<rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>
            17: rustc_middle::ty::relate::relate_substs_with_variances::<rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>
            18: rustc_middle::ty::relate::super_relate_tys::<rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>
            19: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
            20: rustc_borrowck::nll::compute_regions
            21: rustc_borrowck::do_mir_borrowck
            22: rustc_borrowck::mir_borrowck
            23: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
            24: rustc_query_impl::get_query::mir_borrowck
            25: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::VecCache<rustc_hir::hir_id::OwnerId, rustc_middle::query::erase::Erased<[u8; 8]>>>
            26: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>::check
            27: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_nested_item
            28: rustc_hir::intravisit::walk_mod::<rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>
            29: rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait
            30: rustc_hir_analysis::collect::type_of::type_of
            31: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt>
            32: rustc_query_impl::get_query::type_of
            33: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
            34: rustc_hir_analysis::check::check::check_mod_item_types
            35: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
            36: rustc_query_impl::get_query::check_mod_item_types
            37: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
            38: <rustc_session::session::Session>::time::<(), rustc_hir_analysis::check_crate::{closure#6}>
            39: rustc_hir_analysis::check_crate
            40: rustc_interface::passes::analysis
            41: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
            42: rustc_query_impl::get_query::analysis
            43: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
            44: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
            45: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
            46: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            47: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
            48: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
            49: std::sys::unix::thread::Thread::new::thread_start
                       at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/std/src/sys/unix/thread.rs:108:17
            50: start_thread
            51: clone
          

error: internal compiler error: Failed to unify obligation `Obligation(predicate=AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (ImplT,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, depth=0)` with poly_projection `Binder(ProjectionPredicate(AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (i32,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, Term::Ty(())), [])`: Sorts(ExpectedFound { expected: i32, found: ImplT })
  --> src/lib.rs:19:5
   |
19 | /     Foo::<i32, _> {
20 | |         f: |_| (),
21 | |         _phantom: PhantomData,
22 | |     }
   | |_____^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
              2: <rustc_middle::ty::context::TyCtxt>::ty_error_with_message::<rustc_span::span_encoding::Span>
              3: rustc_trait_selection::traits::project::confirm_param_env_candidate
              4: rustc_trait_selection::traits::project::opt_normalize_projection_type
              5: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_trait_selection::traits::project::ProjectAndUnifyResult, rustc_infer::traits::project::MismatchedProjectionTypes, rustc_trait_selection::traits::project::poly_project_and_unify_type::{closure#0}>
              6: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
              7: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
              8: <rustc_trait_selection::traits::engine::ObligationCtxt>::select_all_or_error
              9: rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints::<rustc_borrowck::type_check::InstantiateOpaqueType, (), <rustc_borrowck::type_check::InstantiateOpaqueType as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform::{closure#0}>
             10: <rustc_borrowck::type_check::TypeChecker>::fully_perform_op::<(), rustc_borrowck::type_check::InstantiateOpaqueType>
             11: <rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>::relate_opaques
             12: <rustc_middle::ty::subst::GenericArg as rustc_middle::ty::relate::Relate>::relate::<rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>
             13: rustc_middle::ty::relate::relate_substs_with_variances::<rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>
             14: rustc_middle::ty::relate::super_relate_tys::<rustc_infer::infer::nll_relate::TypeRelating<rustc_borrowck::type_check::relate_tys::NllTypeRelatingDelegate>>
             15: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
             16: rustc_borrowck::nll::compute_regions
             17: rustc_borrowck::do_mir_borrowck
             18: rustc_borrowck::mir_borrowck
             19: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             20: rustc_query_impl::get_query::mir_borrowck
             21: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::VecCache<rustc_hir::hir_id::OwnerId, rustc_middle::query::erase::Erased<[u8; 8]>>>
             22: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>::check
             23: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_nested_item
             24: rustc_hir::intravisit::walk_mod::<rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>
             25: rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait
             26: rustc_hir_analysis::collect::type_of::type_of
             27: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt>
             28: rustc_query_impl::get_query::type_of
             29: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
             30: rustc_hir_analysis::check::check::check_mod_item_types
             31: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             32: rustc_query_impl::get_query::check_mod_item_types
             33: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             34: <rustc_session::session::Session>::time::<(), rustc_hir_analysis::check_crate::{closure#6}>
             35: rustc_hir_analysis::check_crate
             36: rustc_interface::passes::analysis
             37: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             38: rustc_query_impl::get_query::analysis
             39: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             40: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
             41: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             42: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             43: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             44: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             45: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/std/src/sys/unix/thread.rs:108:17
             46: start_thread
             47: clone
           

error: internal compiler error: Failed to unify obligation `Obligation(predicate=AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (ImplT,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, depth=0)` with poly_projection `Binder(ProjectionPredicate(AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (i32,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, Term::Ty(())), [])`: Sorts(ExpectedFound { expected: i32, found: ImplT })
  --> src/lib.rs:19:5
   |
19 | /     Foo::<i32, _> {
20 | |         f: |_| (),
21 | |         _phantom: PhantomData,
22 | |     }
   | |_____^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
              2: <rustc_middle::ty::context::TyCtxt>::ty_error_with_message::<rustc_span::span_encoding::Span>
              3: rustc_trait_selection::traits::project::confirm_param_env_candidate
              4: rustc_trait_selection::traits::project::opt_normalize_projection_type
              5: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_trait_selection::traits::project::ProjectAndUnifyResult, rustc_infer::traits::project::MismatchedProjectionTypes, rustc_trait_selection::traits::project::poly_project_and_unify_type::{closure#0}>
              6: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
              7: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
              8: <rustc_trait_selection::traits::engine::ObligationCtxt>::select_all_or_error
              9: <rustc_infer::infer::InferCtxt as rustc_borrowck::region_infer::opaque_types::InferCtxtExt>::infer_opaque_definition_from_instantiation
             10: <rustc_borrowck::region_infer::RegionInferenceContext>::infer_opaque_types
             11: rustc_borrowck::nll::compute_regions
             12: rustc_borrowck::do_mir_borrowck
             13: rustc_borrowck::mir_borrowck
             14: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             15: rustc_query_impl::get_query::mir_borrowck
             16: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::VecCache<rustc_hir::hir_id::OwnerId, rustc_middle::query::erase::Erased<[u8; 8]>>>
             17: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>::check
             18: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_nested_item
             19: rustc_hir::intravisit::walk_mod::<rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>
             20: rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait
             21: rustc_hir_analysis::collect::type_of::type_of
             22: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt>
             23: rustc_query_impl::get_query::type_of
             24: rustc_middle::ty::query::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
             25: rustc_hir_analysis::check::check::check_mod_item_types
             26: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             27: rustc_query_impl::get_query::check_mod_item_types
             28: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             29: <rustc_session::session::Session>::time::<(), rustc_hir_analysis::check_crate::{closure#6}>
             30: rustc_hir_analysis::check_crate
             31: rustc_interface::passes::analysis
             32: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             33: rustc_query_impl::get_query::analysis
             34: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             35: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
             36: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             37: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             38: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             39: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             40: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/std/src/sys/unix/thread.rs:108:17
             41: start_thread
             42: clone
           

error: internal compiler error: Failed to unify obligation `Obligation(predicate=AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (ImplT,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, depth=0)` with poly_projection `Binder(ProjectionPredicate(AliasTy { substs: [[closure@src/lib.rs:20:12: 20:15], (i32,)], def_id: DefId(2:2922 ~ core[7de8]::ops::function::FnOnce::Output) }, Term::Ty(())), [])`: Sorts(ExpectedFound { expected: i32, found: ImplT })
  --> src/lib.rs:15:27
   |
15 | type FooImpl = Foo<ImplT, impl FnOnce(ImplT)>;
   |                           ^^^^^^^^^^^^^^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
              2: <rustc_middle::ty::context::TyCtxt>::ty_error_with_message::<rustc_span::span_encoding::Span>
              3: rustc_trait_selection::traits::project::confirm_param_env_candidate
              4: rustc_trait_selection::traits::project::opt_normalize_projection_type
              5: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_trait_selection::traits::project::ProjectAndUnifyResult, rustc_infer::traits::project::MismatchedProjectionTypes, rustc_trait_selection::traits::project::poly_project_and_unify_type::{closure#0}>
              6: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
              7: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
              8: <rustc_trait_selection::traits::engine::ObligationCtxt>::select_all_or_error
              9: rustc_hir_analysis::check::check::check_mod_item_types
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             11: rustc_query_impl::get_query::check_mod_item_types
             12: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             13: <rustc_session::session::Session>::time::<(), rustc_hir_analysis::check_crate::{closure#6}>
             14: rustc_hir_analysis::check_crate
             15: rustc_interface::passes::analysis
             16: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             17: rustc_query_impl::get_query::analysis
             18: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             19: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
             20: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
             21: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             22: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             23: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/alloc/src/boxed.rs:1985:9
             24: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/cba14074bb4cc12bfe918eabd0d52a3999b2a461/library/std/src/sys/unix/thread.rs:108:17
             25: start_thread
             26: clone
           

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 1.71.0-nightly (cba14074b 2023-05-10) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack

The text was updated successfully, but these errors were encountered:

Jules-Bertholet · 2023-05-12T01:45:05Z

@rustbot label requires-nightly F-type_alias_impl_trait

matthiaskrgr · 2023-06-11T17:03:57Z

Regression in nightly-2023-02-22
Regression in f4c7596
#108311 cc @oli-obk

matthiaskrgr · 2024-01-09T22:42:50Z

still crashing, rustc 1.77.0-nightly (ca663b0 2024-01-08)

Rollup merge of rust-lang#119816 - oli-obk:tait_ice_unify_obligations, r=lcnr Define hidden types in confirmation fixes rust-lang#111470 r? `@lcnr` or `@compiler-errors` explanation in the newly added test

VictorBulba added C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels May 11, 2023

compiler-errors self-assigned this May 11, 2023

rustbot added F-type_alias_impl_trait `#[feature(type_alias_impl_trait)]` requires-nightly This issue requires a nightly compiler in some way. labels May 12, 2023

compiler-errors removed their assignment May 12, 2023

oli-obk self-assigned this Jun 14, 2023

rust-lang-glacier-bot added the glacier ICE tracked in rust-lang/glacier. label Jun 25, 2023

oli-obk mentioned this issue Jan 10, 2024

Define hidden types in confirmation #119816

Merged

bors closed this as completed in d4b276c Jan 16, 2024

github-actions bot mentioned this issue Jan 17, 2024

ices/111470.rs: fixed with no errors rust-lang/glacier#1710

Merged

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ICE TAIT: Failed to unify obligation; no errors encountered even though `delay_span_bug` issued #111470

ICE TAIT: Failed to unify obligation; no errors encountered even though `delay_span_bug` issued #111470

VictorBulba commented May 11, 2023 •

edited

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Jules-Bertholet commented May 12, 2023

matthiaskrgr commented Jun 11, 2023

matthiaskrgr commented Jan 9, 2024

ICE TAIT: Failed to unify obligation; no errors encountered even though delay_span_bug issued #111470

ICE TAIT: Failed to unify obligation; no errors encountered even though delay_span_bug issued #111470

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VictorBulba commented May 11, 2023 • edited Loading

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Error output

Jules-Bertholet commented May 12, 2023

matthiaskrgr commented Jun 11, 2023

matthiaskrgr commented Jan 9, 2024

ICE TAIT: Failed to unify obligation; no errors encountered even though `delay_span_bug` issued #111470

ICE TAIT: Failed to unify obligation; no errors encountered even though `delay_span_bug` issued #111470

VictorBulba commented May 11, 2023 •

edited

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