ICE: `<_ as MyTrait<Ty1>>::Out` where `trait MyTrait<T: OtherTrait<Assoc = Self>>>` on nightly

[polina4096]

Code

struct Ty1;
struct Ty2;
struct Ty3;

pub trait TraitAssoc {
    type Assoc;
}

impl TraitAssoc for Ty1 {
    type Assoc = Ty2;
}

trait MyTrait<T: TraitAssoc<Assoc = Self>> {
    type Out;
}

impl<T: TraitAssoc<Assoc = Ty2>> MyTrait<T> for Ty2 {
    type Out = Ty3;
}

fn main() {
    let _: <_ as MyTrait<Ty1>>::Out;
}

Meta

rustc --version --verbose:

rustc 1.75.0-nightly (a2f5f9691 2023-11-02)
binary: rustc
commit-hash: a2f5f9691b6ce64c1703feaf9363710dfd7a56cf
commit-date: 2023-11-02
host: aarch64-apple-darwin
release: 1.75.0-nightly
LLVM version: 17.0.4

Error output

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

error: internal compiler error: ambiguity performing ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: UserFacing }, value: AscribeUserType { mir_ty: Ty3, user_ty: Ty(Alias(Projection, AliasTy { args: [?0t, Ty1], def_id: DefId(0:15 ~ trait_assoc_ice[4360]::MyTrait::Out) })) } }
  --> src/main.rs:22:12
   |
22 |     let _: <_ as MyTrait<Ty1>>::Out;
   |            ^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: delayed at /rustc/a2f5f9691b6ce64c1703feaf9363710dfd7a56cf/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs:170:26
         0: std::backtrace::Backtrace::create
         1: <rustc_errors::HandlerInner>::emit_diagnostic
         2: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         3: <rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::AscribeUserType> as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform
         4: <rustc_borrowck::type_check::TypeChecker>::ascribe_user_type
         5: rustc_borrowck::type_check::type_check
         6: rustc_borrowck::nll::compute_regions
         7: rustc_borrowck::do_mir_borrowck
         8: rustc_borrowck::mir_borrowck
         9: 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]>>
        10: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
        11: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, 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: std::panicking::try::<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>>
        14: <rustc_data_structures::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
        15: rustc_data_structures::sync::parallel::disabled::par_for_each_in::<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>
        16: <rustc_session::session::Session>::time::<(), rustc_interface::passes::analysis::{closure#1}>
        17: rustc_interface::passes::analysis
        18: 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; 1]>>
        19: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
        20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        21: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
        22: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#6}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        23: rustc_span::set_source_map::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
        24: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<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>>
        25: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_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>>
        26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_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}
        27: std::sys::unix::thread::Thread::new::thread_start
        28: __pthread_joiner_wake
  --> src/main.rs:22:12
   |
22 |     let _: <_ as MyTrait<Ty1>>::Out;
   |            ^^^^^^^^^^^^^^^^^^^^^^^^

error: internal compiler error: ambiguity performing ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: UserFacing }, value: AscribeUserType { mir_ty: Ty3, user_ty: Ty(Alias(Projection, AliasTy { args: [?1t, Ty1], def_id: DefId(0:15 ~ trait_assoc_ice[4360]::MyTrait::Out) })) } }
  --> src/main.rs:22:12
   |
22 |     let _: <_ as MyTrait<Ty1>>::Out;
   |            ^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: delayed at /rustc/a2f5f9691b6ce64c1703feaf9363710dfd7a56cf/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs:170:26
         0: std::backtrace::Backtrace::create
         1: <rustc_errors::HandlerInner>::emit_diagnostic
         2: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         3: <rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::AscribeUserType> as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform
         4: <rustc_borrowck::type_check::TypeChecker>::ascribe_user_type
         5: rustc_borrowck::type_check::type_check
         6: rustc_borrowck::nll::compute_regions
         7: rustc_borrowck::do_mir_borrowck
         8: rustc_borrowck::mir_borrowck
         9: 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]>>
        10: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
        11: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, 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: std::panicking::try::<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>>
        14: <rustc_data_structures::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
        15: rustc_data_structures::sync::parallel::disabled::par_for_each_in::<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>
        16: <rustc_session::session::Session>::time::<(), rustc_interface::passes::analysis::{closure#1}>
        17: rustc_interface::passes::analysis
        18: 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; 1]>>
        19: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
        20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        21: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
        22: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#6}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        23: rustc_span::set_source_map::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
        24: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<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>>
        25: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_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>>
        26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_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}
        27: std::sys::unix::thread::Thread::new::thread_start
        28: __pthread_joiner_wake
  --> src/main.rs:22:12
   |
22 |     let _: <_ as MyTrait<Ty1>>::Out;
   |            ^^^^^^^^^^^^^^^^^^^^^^^^

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 attach the file at `/Users/polina/Development/trait-assoc-ice/rustc-ice-2023-11-04T17_25_07-6038.txt` to your bug report

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C split-debuginfo=unpacked -C incremental=[REDACTED]

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

query stack during panic:
end of query stack

Backtrace

delayed span bug: ambiguity performing ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: UserFacing }, value: AscribeUserType { mir_ty: Ty3, user_ty: Ty(Alias(Projection, AliasTy { args: [?0t, Ty1], def_id: DefId(0:15 ~ trait_assoc_ice[d1be]::MyTrait::Out) })) } }
   0: std::backtrace::Backtrace::create
   1: <rustc_errors::HandlerInner>::emit_diagnostic
   2: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
   3: <rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::AscribeUserType> as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform
   4: <rustc_borrowck::type_check::TypeChecker>::ascribe_user_type
   5: rustc_borrowck::type_check::type_check
   6: rustc_borrowck::nll::compute_regions
   7: rustc_borrowck::do_mir_borrowck
   8: rustc_borrowck::mir_borrowck
   9: 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]>>
  10: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
  11: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, 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: std::panicking::try::<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>>
  14: <rustc_data_structures::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  15: rustc_data_structures::sync::parallel::disabled::par_for_each_in::<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>
  16: <rustc_session::session::Session>::time::<(), rustc_interface::passes::analysis::{closure#1}>
  17: rustc_interface::passes::analysis
  18: 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; 1]>>
  19: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
  20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
  21: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  22: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#6}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
  23: rustc_span::set_source_map::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  24: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<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>>
  25: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_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>>
  26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_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}
  27: std::sys::unix::thread::Thread::new::thread_start
  28: __pthread_joiner_wake

delayed span bug: ambiguity performing ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: UserFacing }, value: AscribeUserType { mir_ty: Ty3, user_ty: Ty(Alias(Projection, AliasTy { args: [?1t, Ty1], def_id: DefId(0:15 ~ trait_assoc_ice[d1be]::MyTrait::Out) })) } }
   0: std::backtrace::Backtrace::create
   1: <rustc_errors::HandlerInner>::emit_diagnostic
   2: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
   3: <rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::AscribeUserType> as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform
   4: <rustc_borrowck::type_check::TypeChecker>::ascribe_user_type
   5: rustc_borrowck::type_check::type_check
   6: rustc_borrowck::nll::compute_regions
   7: rustc_borrowck::do_mir_borrowck
   8: rustc_borrowck::mir_borrowck
   9: 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]>>
  10: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
  11: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, 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: std::panicking::try::<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>>
  14: <rustc_data_structures::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures::sync::parallel::disabled::par_for_each_in<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>::{closure#0}::{closure#0}::{closure#0}>
  15: rustc_data_structures::sync::parallel::disabled::par_for_each_in::<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_interface::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>
  16: <rustc_session::session::Session>::time::<(), rustc_interface::passes::analysis::{closure#1}>
  17: rustc_interface::passes::analysis
  18: 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; 1]>>
  19: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
  20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
  21: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  22: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#6}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
  23: rustc_span::set_source_map::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  24: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<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>>
  25: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_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>>
  26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_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}
  27: std::sys::unix::thread::Thread::new::thread_start
  28: __pthread_joiner_wake



rustc version: 1.75.0-nightly (a2f5f9691 2023-11-02)
platform: aarch64-apple-darwin

query stack during panic:
end of query stack

[polina4096]

searched nightlies: from nightly-2023-10-01 to nightly-2023-11-04
regressed nightly: nightly-2023-10-12
searched commit range: d627cf0...475c71d
regressed commit: 36cbf94

bisected with cargo-bisect-rustc v0.6.7

Host triple: aarch64-apple-darwin
Reproduce with:

cargo bisect-rustc --start=2023-10-01 --end=2023-11-04

[lqd]

That’s from #116530 cc @aliemjay: was this done on purpose maybe to find cases like this?

[compiler-errors]

Why the heck do we even resolve <_ as MyTrait<Ty1>>::Out in the first place?!

edit: This behavior changed in:

commit[0] 2023-01-08: Auto merge of #106449 - GuillaumeGomez:rustdoc-gui-retry-mechanism, r=Mark-Simulacrum
commit[1] 2023-01-08: Auto merge of #90291 - geeklint:loosen_weak_debug_bound, r=dtolnay
commit[2] 2023-01-09: Auto merge of #106616 - compiler-errors:rollup-emcj0o3, r=compiler-errors
commit[3] 2023-01-09: Auto merge of #106582 - compiler-errors:better-spans-on-bad-tys, r=lcnr
commit[4] 2023-01-09: Auto merge of #106340 - saethlin:propagate-operands, r=oli-obk
commit[5] 2023-01-09: Auto merge of #101947 - aliemjay:astconv-normalize, r=lcnr
commit[6] 2023-01-09: Auto merge of #106637 - fee1-dead-contrib:rollup-ticvmsd, r=fee1-dead

[compiler-errors]

Ah, it's because of the where-clause on MyTrait. This would be fixed if checked wf in AscribeUserType before normalization and not after, since that sufficiently constrains the self type of the projection so it can proceed in the query. cc: @aliemjay

[aliemjay]

This is ultimately fixed by #104098, but until then the PR #116530 should be temporarily reverted (with a beta-1.75 backport).

I'll do the revert when the crater run for beta-1.75 finishes in order to discover other regressions. The reverted commit is small and safe enough to backport at any time, I believe, so I'm fine with this. Please let me know if you think this should be done earlier.

@rustbot claim