[ICE]: broken mir, -Zvalidate-mir

[matthiaskrgr]

Code

// ./tests/ui/impl-trait/nested-return-type2.rs

// check-pass

trait Duh {}

impl Duh for i32 {}

trait Trait {
    type Assoc: Duh;
}

impl<R: Duh, F: FnMut() -> R> Trait for F {
    type Assoc = R;
}


fn foo() -> impl Trait<Assoc = impl Send> {
    || 42
}

fn main() {
}

Affected release channels

• Previous Stable
• Current Stable
• Current Beta
• Current Nightly

Rust Version

rustc 1.69.0-nightly (d7948c843 2023-01-26)
binary: rustc
commit-hash: d7948c843de94245c794e8c63dd4301a78bb5ba3
commit-date: 2023-01-26
host: x86_64-unknown-linux-gnu
release: 1.69.0-nightly
LLVM version: 15.0.7

Current error output

--> ./tests/ui/impl-trait/nested-return-type2.rs:16:4
   |
16 | fn foo() -> impl Trait<Assoc = impl Send> {
   |    ^^^
   |
   = note: `#[warn(dead_code)]` on by default

warning: opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
  --> ./tests/ui/impl-trait/nested-return-type2.rs:16:24
   |
8  |     type Assoc: Duh;
   |                 --- this associated type bound is unsatisfied for `impl Send`
...
16 | fn foo() -> impl Trait<Assoc = impl Send> {
   |                        ^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
help: add this bound
   |
16 | fn foo() -> impl Trait<Assoc = impl Send + Duh> {
   |                                          +++++

Backtrace

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

error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (before pass CheckPackedRef) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (after pass CheckPackedRef) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (before pass CheckConstItemMutation) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (after pass CheckConstItemMutation) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (before pass FunctionItemReferences) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (after pass FunctionItemReferences) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (before pass SimplifyCfg-initial) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (after pass SimplifyCfg-initial) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (before pass SanityCheck) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (after pass SanityCheck) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
  --> ./tests/ui/impl-trait/nested-return-type2.rs:17:5
   |
17 |     || 42
   |     ^^^^^
   |
   = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
              1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
              2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
              3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
              4: rustc_mir_transform::pass_manager::validate_body
              5: rustc_mir_transform::mir_const
              6: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_const, rustc_query_impl::plumbing::QueryCtxt>
              7: rustc_mir_transform::mir_promoted
              8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_promoted, rustc_query_impl::plumbing::QueryCtxt>
              9: rustc_borrowck::mir_borrowck
             10: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
             11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
             12: rustc_hir_analysis::collect::type_of::type_of
             13: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             14: rustc_hir_analysis::check::check::check_mod_item_types
             15: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
             16: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
             17: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
             18: rustc_hir_analysis::check_crate
             19: rustc_interface::passes::analysis
             20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
             21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
             22: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             23: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             25: 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_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
             26: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             27: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             28: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/alloc/src/boxed.rs:1988:9
             29: std::sys::unix::thread::Thread::new::thread_start
                        at /rustc/d7948c843de94245c794e8c63dd4301a78bb5ba3/library/std/src/sys/unix/thread.rs:108:17
             30: <unknown>
             31: <unknown>


error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:11 ~ nested_return_type2[d0e8]::foo), const_param_did: None }) (before pass PromoteTemps) at bb0[0]:
                                encountered `Assign((_0, [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]))` with incompatible types:
                                left-hand side has type: impl Trait<Assoc = impl Send>
                                right-hand side has type: [closure@./tests/ui/impl-trait/nested-return-type2.rs:17:5: 17:7]
 <snip>
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 1.69.0-nightly (d7948c843 2023-01-26) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z validate-mir

query stack during panic:
end of query stack
error: aborting due to 16 previous errors; 2 warnings emitted

Anything else?

No response

[matthiaskrgr]

searched toolchains 95b61d1 through a2d002a

---

Regression in 40fda7b

---

[matthiaskrgr]

I wonder if this is #107074 cc @lcnr ?

[lcnr]

very likely 🤔 will revert #107074 if we don't figure out how to fix this in the near future

[trinity-1686a]

I'm hitting a very similar issue, but without -Z validate-mir (only --crate-type rlib -C embed-bitcode=no -C debuginfo=2 which is provided by cargo)

compiler logs

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

error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:2812 ~ combine[2263]::stream::{impl#47}::reset), const_param_did: None }) (after phase change to runtime-optimized) at bb0[3]:
                                encountered `Assign((_0, const Result::<(), StringStreamError>::Ok(())))` with incompatible types:
                                left-hand side has type: Result<(), <&str as StreamOnce>::Error>
                                right-hand side has type: Result<(), StringStreamError>
   --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/combine-4.6.6/src/stream/mod.rs:44:17
    |
44  |                 Ok(())
    |                 ^^^^^^
...
153 | clone_resetable! {('a) &'a str}
    | ------------------------------- in this macro invocation
    |
    = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
               1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
               2: <rustc_const_eval::transform::validate::TypeChecker>::fail::<alloc::string::String>
               3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
               4: rustc_mir_transform::optimized_mir
               5: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::optimized_mir, rustc_query_impl::plumbing::QueryCtxt>
               6: <rustc_metadata::rmeta::encoder::EncodeContext>::encode_crate_root
               7: rustc_metadata::rmeta::encoder::encode_metadata_impl
               8: rustc_data_structures::sync::join::<rustc_metadata::rmeta::encoder::encode_metadata::{closure#0}, rustc_metadata::rmeta::encoder::encode_metadata::{closure#1}, (), ()>
               9: rustc_metadata::rmeta::encoder::encode_metadata
              10: rustc_metadata::fs::encode_and_write_metadata
              11: rustc_interface::passes::start_codegen
              12: <rustc_interface::passes::QueryContext>::enter::<<rustc_interface::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core::result::Result<alloc::boxed::Box<dyn core::any::Any>, rustc_errors::ErrorGuaranteed>>
              13: <rustc_interface::queries::Queries>::ongoing_codegen
              14: <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_errors::ErrorGuaranteed>>
              15: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
              16: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
              17: 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_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
              18: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
              19: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                         at /rustc/bd39bbb4bb92df439bf6d85470e296cc6a47ffbd/library/alloc/src/boxed.rs:1988:9
              20: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                         at /rustc/bd39bbb4bb92df439bf6d85470e296cc6a47ffbd/library/alloc/src/boxed.rs:1988:9
              21: std::sys::unix::thread::Thread::new::thread_start
                         at /rustc/bd39bbb4bb92df439bf6d85470e296cc6a47ffbd/library/std/src/sys/unix/thread.rs:108:17
              22: <unknown>
              23: <unknown>
            
    = note: this error: internal compiler error originates in the macro `clone_resetable` (in Nightly builds, run with -Z macro-backtrace for more info)

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 1.69.0-nightly (bd39bbb4b 2023-02-07) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C instrument-coverage

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

query stack during panic:
end of query stack

However I don't get the issue when building with --release

edit: my bad I'm experiencing #107678

[apiraino]

WG-prioritization assigning priority (Zulip discussion).

@rustbot label -I-prioritize +P-medium

[apiraino]

bisection tested with rustc +nightly "-Zvalidate-mir" repro.rs, seems to point to commit 40fda7b

searched nightlies: from nightly-2023-01-15 to nightly-2023-02-09
regressed nightly: nightly-2023-01-27
searched commit range: c18a5e8...d7948c8
regressed commit: 40fda7b

bisected with cargo-bisect-rustc v0.6.5

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --start=2023-01-15 --script script2.sh --regress ice 

it's a rollup of:

- https://github.com/rust-lang/rust/pull/97373 (impl DispatchFromDyn for Cell and UnsafeCell)
- https://github.com/rust-lang/rust/pull/106625 (Remove backwards compat for LLVM 12 coverage format)
- https://github.com/rust-lang/rust/pull/106779 (Avoid __cxa_thread_atexit_impl on Emscripten)
- https://github.com/rust-lang/rust/pull/106811 (Append .dwp to the binary filename instead of replacing the existing extension.)
- https://github.com/rust-lang/rust/pull/106836 (Remove optimistic spinning from `mpsc::SyncSender`)
- https://github.com/rust-lang/rust/pull/106946 (implement Hash for proc_macro::LineColumn)
- https://github.com/rust-lang/rust/pull/107074 (remove unnecessary check for opaque types)
- https://github.com/rust-lang/rust/pull/107287 (Improve fn pointer notes)
- https://github.com/rust-lang/rust/pull/107304 (Use `can_eq` to compare types for default assoc type error)

[matthiaskrgr]

@apiraino I already bisected this one (see second comment :D)
@lcnr any should we revert now? it's still ICEing