Repository: rust
Issue: Incremental compilation ICE "forcing query with already existing `DepNode` …" using `ouroboros`
Labels: I-ICE,T-compiler,A-incr-comp,C-bug,E-needs-mcve

Reproduces on this change
```diff
/*
[dependencies]
ouroboros = "0.15.5"
*/
use ouroboros::*;

type F<'a> = fn(&'a ());

#[self_referencing]
struct S<'a> {
    o: Box<F<'a>>,
    #[borrows(o)]
-   r: &'this u8,
+   r: &'this str,
}
fn main() {
    println!("");
}
```
[try it out online here](https://www.rustexplorer.com/b#%2F*%0A%5Bdependencies%5D%0Aouroboros%20%3D%20%220.15.5%22%0A*%2F%0Ause%20ouroboros%3A%3A*%3B%0A%0Atype%20F%3C'a%3E%20%3D%20fn(%26'a%20())%3B%0A%0A%23%5Bself_referencing%5D%0Astruct%20S%3C'a%3E%20%7B%0A%20%20%20%20o%3A%20Box%3CF%3C'a%3E%3E%2C%0A%20%20%20%20%23%5Bborrows(o)%5D%0A%20%20%20%20r%3A%20%26'this%20u8%2C%20%2F%2F%20Run%2C%20change%20this%20line%20to%20%60%26'this%20str%60%2C%20run%20again.%0A%7D%0Afn%20main()%20%7B%0A%20%20%20%20println!(%22%22)%3B%0A%7D%0A)
```
   Compiling playground v0.1.0 (/home/explorer/playground)
thread 'rustc' panicked at 'forcing query with already existing `DepNode`
- query-key: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }], value: ParamEnvAnd { param_env: ParamEnv { caller_bounds: [Binder(TraitPredicate(<RBuilder_ as std::marker::Sized>, polarity:Positive), []), Binder(TraitPredicate(<RBuilder_ as std::ops::FnOnce<(&'this std::boxed::Box<fn(&'a ())>,)>>, polarity:Positive), [Region(BrNamed(DefId(0:36 ~ playground[0a24]::ouroboros_impl_s::{impl#1}::'this), 'this))]), Binder(ProjectionPredicate(AliasTy { substs: [RBuilder_, (&'this std::boxed::Box<fn(&'a ())>,)], def_id: DefId(2:2924 ~ core[0486]::ops::function::FnOnce::Output), _use_mk_alias_ty_instead: () }, Term::Ty(std::pin::Pin<std::boxed::Box<(dyn std::future::Future<Output = &'this str> + 'this)>>)), [Region(BrNamed(DefId(0:36 ~ playground[0a24]::ouroboros_impl_s::{impl#1}::'this), 'this))])], reveal: UserFacing, constness: NotConst }, value: Normalize { value: [async fn body@src/main.rs:9:1: 9:20] } } }
- dep-node: type_op_normalize_ty(564da9a8061554a1-b3a54dc468e93f1e)', /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/compiler/rustc_query_system/src/dep_graph/graph.rs:316:9
stack backtrace:
   0:     0x7f976138e85a - std::backtrace_rs::backtrace::libunwind::trace::h51cb40f2f8f23f31
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f976138e85a - std::backtrace_rs::backtrace::trace_unsynchronized::hebc3338ffed58a56
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f976138e85a - std::sys_common::backtrace::_print_fmt::h136f982a4680ac7f
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f976138e85a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd1514baae6e42eb6
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f97613f136e - core::fmt::write::hfbed4b54a5eebfee
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/core/src/fmt/mod.rs:1208:17
   5:     0x7f976137ebd5 - std::io::Write::write_fmt::h9f6098b6a54a9a94
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/io/mod.rs:1682:15
   6:     0x7f976138e625 - std::sys_common::backtrace::_print::h6e7a2bc7da6ecf73
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f976138e625 - std::sys_common::backtrace::print::h631b25ef82a0eea1
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f976139136f - std::panicking::default_hook::{{closure}}::h41299fc951b157c9
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/panicking.rs:267:22
   9:     0x7f97613910ab - std::panicking::default_hook::hd317023abfdceaed
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/panicking.rs:286:9
  10:     0x7f976465dcc1 - rustc_driver[8fc339cf4408bec4]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f9761391bad - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h813f31c5cc72640d
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/alloc/src/boxed.rs:2032:9
  12:     0x7f9761391bad - std::panicking::rust_panic_with_hook::h2e61684db9120e8e
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/panicking.rs:692:13
  13:     0x7f9761391929 - std::panicking::begin_panic_handler::{{closure}}::h63d39cc19c97d34a
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/panicking.rs:579:13
  14:     0x7f976138ed0c - std::sys_common::backtrace::__rust_end_short_backtrace::h8da6b271e1c3c543
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/sys_common/backtrace.rs:137:18
  15:     0x7f9761391632 - rust_begin_unwind
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/panicking.rs:575:5
  16:     0x7f97613edd53 - core::panicking::panic_fmt::h89c37196e57a859c
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/core/src/panicking.rs:64:14
  17:     0x7f97639bc3a1 - <rustc_query_system[259206d12eac588b]::dep_graph::graph::DepGraph<rustc_middle[1a40b9d11a76de60]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, rustc_middle[1a40b9d11a76de60]::infer::canonical::Canonical<rustc_middle[1a40b9d11a76de60]::ty::ParamEnvAnd<rustc_middle[1a40b9d11a76de60]::traits::query::type_op::Normalize<rustc_middle[1a40b9d11a76de60]::ty::Ty>>>, core[486592e7c49a8aa]::result::Result<&rustc_middle[1a40b9d11a76de60]::infer::canonical::Canonical<rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryResponse<rustc_middle[1a40b9d11a76de60]::ty::Ty>>, rustc_middle[1a40b9d11a76de60]::traits::query::NoSolution>>
  18:     0x7f97639baa59 - rustc_query_system[259206d12eac588b]::query::plumbing::try_execute_query::<rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt, rustc_query_system[259206d12eac588b]::query::caches::DefaultCache<rustc_middle[1a40b9d11a76de60]::infer::canonical::Canonical<rustc_middle[1a40b9d11a76de60]::ty::ParamEnvAnd<rustc_middle[1a40b9d11a76de60]::traits::query::type_op::Normalize<rustc_middle[1a40b9d11a76de60]::ty::Ty>>>, core[486592e7c49a8aa]::result::Result<&rustc_middle[1a40b9d11a76de60]::infer::canonical::Canonical<rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryResponse<rustc_middle[1a40b9d11a76de60]::ty::Ty>>, rustc_middle[1a40b9d11a76de60]::traits::query::NoSolution>>>
  19:     0x7f97639ba1cd - rustc_query_system[259206d12eac588b]::query::plumbing::get_query::<rustc_query_impl[bc8faa08c5c89942]::queries::type_op_normalize_ty, rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt>
  20:     0x7f97639ba113 - <rustc_query_impl[bc8faa08c5c89942]::Queries as rustc_middle[1a40b9d11a76de60]::ty::query::QueryEngine>::type_op_normalize_ty
  21:     0x7f976331abb3 - <rustc_middle[1a40b9d11a76de60]::ty::ParamEnvAnd<rustc_middle[1a40b9d11a76de60]::traits::query::type_op::Normalize<rustc_middle[1a40b9d11a76de60]::ty::Ty>> as rustc_trait_selection[e881d80e291c2cd6]::traits::query::type_op::TypeOp>::fully_perform
  22:     0x7f97632a6630 - <&mut <rustc_borrowck[c86664c7788b1f3c]::type_check::free_region_relations::UniversalRegionRelationsBuilder>::create::{closure#0} as core[486592e7c49a8aa]::ops::function::FnOnce<(rustc_middle[1a40b9d11a76de60]::ty::Ty,)>>::call_once
  23:     0x7f97632a5f32 - <alloc[1a97d1c4ba9fe4a2]::vec::Vec<&rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryRegionConstraints> as alloc[1a97d1c4ba9fe4a2]::vec::spec_from_iter::SpecFromIter<&rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryRegionConstraints, core[486592e7c49a8aa]::iter::adapters::flatten::FlatMap<core[486592e7c49a8aa]::iter::adapters::chain::Chain<core[486592e7c49a8aa]::iter::adapters::cloned::Cloned<core[486592e7c49a8aa]::slice::iter::Iter<rustc_middle[1a40b9d11a76de60]::ty::Ty>>, core[486592e7c49a8aa]::option::IntoIter<rustc_middle[1a40b9d11a76de60]::ty::Ty>>, core[486592e7c49a8aa]::iter::adapters::chain::Chain<core[486592e7c49a8aa]::iter::adapters::chain::Chain<core[486592e7c49a8aa]::option::IntoIter<&rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryRegionConstraints>, core[486592e7c49a8aa]::option::IntoIter<&rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryRegionConstraints>>, core[486592e7c49a8aa]::option::IntoIter<&rustc_middle[1a40b9d11a76de60]::infer::canonical::QueryRegionConstraints>>, <rustc_borrowck[c86664c7788b1f3c]::type_check::free_region_relations::UniversalRegionRelationsBuilder>::create::{closure#0}>>>::from_iter
  24:     0x7f97632a12a4 - rustc_borrowck[c86664c7788b1f3c]::type_check::free_region_relations::create
  25:     0x7f9763295910 - rustc_borrowck[c86664c7788b1f3c]::type_check::type_check
  26:     0x7f9763266a35 - rustc_borrowck[c86664c7788b1f3c]::nll::compute_regions
  27:     0x7f976324b3ac - rustc_borrowck[c86664c7788b1f3c]::do_mir_borrowck
  28:     0x7f9763236c69 - rustc_borrowck[c86664c7788b1f3c]::mir_borrowck
  29:     0x7f9763236145 - <rustc_borrowck[c86664c7788b1f3c]::provide::{closure#0} as core[486592e7c49a8aa]::ops::function::FnOnce<(rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, rustc_span[fd000e025c1fef5b]::def_id::LocalDefId)>>::call_once
  30:     0x7f976363c564 - <rustc_query_system[259206d12eac588b]::dep_graph::graph::DepGraph<rustc_middle[1a40b9d11a76de60]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, rustc_span[fd000e025c1fef5b]::def_id::LocalDefId, &rustc_middle[1a40b9d11a76de60]::mir::query::BorrowCheckResult>
  31:     0x7f976363b32c - rustc_query_system[259206d12eac588b]::query::plumbing::try_execute_query::<rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt, rustc_query_system[259206d12eac588b]::query::caches::VecCache<rustc_span[fd000e025c1fef5b]::def_id::LocalDefId, &rustc_middle[1a40b9d11a76de60]::mir::query::BorrowCheckResult>>
  32:     0x7f976400cf8a - <rustc_query_impl[bc8faa08c5c89942]::Queries as rustc_middle[1a40b9d11a76de60]::ty::query::QueryEngine>::mir_borrowck
  33:     0x7f9763327d21 - <rustc_borrowck[c86664c7788b1f3c]::type_check::TypeChecker>::prove_closure_bounds
  34:     0x7f9763306fc5 - <rustc_borrowck[c86664c7788b1f3c]::type_check::TypeChecker>::typeck_mir
  35:     0x7f9763295c76 - rustc_borrowck[c86664c7788b1f3c]::type_check::type_check
  36:     0x7f9763266a35 - rustc_borrowck[c86664c7788b1f3c]::nll::compute_regions
  37:     0x7f976324b3ac - rustc_borrowck[c86664c7788b1f3c]::do_mir_borrowck
  38:     0x7f9763236c69 - rustc_borrowck[c86664c7788b1f3c]::mir_borrowck
  39:     0x7f9763236145 - <rustc_borrowck[c86664c7788b1f3c]::provide::{closure#0} as core[486592e7c49a8aa]::ops::function::FnOnce<(rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, rustc_span[fd000e025c1fef5b]::def_id::LocalDefId)>>::call_once
  40:     0x7f976363c564 - <rustc_query_system[259206d12eac588b]::dep_graph::graph::DepGraph<rustc_middle[1a40b9d11a76de60]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, rustc_span[fd000e025c1fef5b]::def_id::LocalDefId, &rustc_middle[1a40b9d11a76de60]::mir::query::BorrowCheckResult>
  41:     0x7f976363b32c - rustc_query_system[259206d12eac588b]::query::plumbing::try_execute_query::<rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt, rustc_query_system[259206d12eac588b]::query::caches::VecCache<rustc_span[fd000e025c1fef5b]::def_id::LocalDefId, &rustc_middle[1a40b9d11a76de60]::mir::query::BorrowCheckResult>>
  42:     0x7f9764e2ce86 - rustc_query_system[259206d12eac588b]::query::plumbing::force_query::<rustc_query_impl[bc8faa08c5c89942]::queries::mir_borrowck, rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt>
  43:     0x7f9764f9a1a1 - rustc_query_impl[bc8faa08c5c89942]::plumbing::force_from_dep_node::<rustc_query_impl[bc8faa08c5c89942]::queries::mir_borrowck>
  44:     0x7f97626fb819 - <rustc_query_system[259206d12eac588b]::dep_graph::graph::DepGraph<rustc_middle[1a40b9d11a76de60]::dep_graph::dep_node::DepKind>>::try_mark_previous_green::<rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt>
  45:     0x7f9762f1cba9 - rustc_query_system[259206d12eac588b]::query::plumbing::get_query::<rustc_query_impl[bc8faa08c5c89942]::queries::type_of, rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt>
  46:     0x7f976373e460 - rustc_hir_analysis[1b7141b29bd2e9d]::check::check::check_mod_item_types
  47:     0x7f97631d7ff4 - <rustc_query_system[259206d12eac588b]::dep_graph::graph::DepGraph<rustc_middle[1a40b9d11a76de60]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, rustc_span[fd000e025c1fef5b]::def_id::LocalDefId, ()>
  48:     0x7f97631d618e - rustc_query_system[259206d12eac588b]::query::plumbing::try_execute_query::<rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt, rustc_query_system[259206d12eac588b]::query::caches::VecCache<rustc_span[fd000e025c1fef5b]::def_id::LocalDefId, ()>>
  49:     0x7f9763a4f403 - rustc_query_system[259206d12eac588b]::query::plumbing::get_query::<rustc_query_impl[bc8faa08c5c89942]::queries::check_mod_item_types, rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt>
  50:     0x7f9763cf8a55 - <rustc_middle[1a40b9d11a76de60]::hir::map::Map>::for_each_module::<rustc_hir_analysis[1b7141b29bd2e9d]::check_crate::{closure#6}::{closure#0}>
  51:     0x7f9762bde292 - rustc_hir_analysis[1b7141b29bd2e9d]::check_crate
  52:     0x7f9762bddedb - rustc_interface[58e4822cc60d2a6c]::passes::analysis
  53:     0x7f9763e21e85 - <rustc_query_system[259206d12eac588b]::dep_graph::graph::DepGraph<rustc_middle[1a40b9d11a76de60]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[1a40b9d11a76de60]::ty::context::TyCtxt, (), core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>
  54:     0x7f9763e21048 - rustc_query_system[259206d12eac588b]::query::plumbing::try_execute_query::<rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt, rustc_query_system[259206d12eac588b]::query::caches::DefaultCache<(), core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>>
  55:     0x7f9763e20ab0 - rustc_query_system[259206d12eac588b]::query::plumbing::get_query::<rustc_query_impl[bc8faa08c5c89942]::queries::analysis, rustc_query_impl[bc8faa08c5c89942]::plumbing::QueryCtxt>
  56:     0x7f97638ee4f3 - <rustc_interface[58e4822cc60d2a6c]::passes::QueryContext>::enter::<rustc_driver[8fc339cf4408bec4]::run_compiler::{closure#1}::{closure#2}::{closure#2}, core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>
  57:     0x7f97638ea8a3 - <rustc_interface[58e4822cc60d2a6c]::interface::Compiler>::enter::<rustc_driver[8fc339cf4408bec4]::run_compiler::{closure#1}::{closure#2}, core[486592e7c49a8aa]::result::Result<core[486592e7c49a8aa]::option::Option<rustc_interface[58e4822cc60d2a6c]::queries::Linker>, rustc_errors[5442e185e098f882]::ErrorGuaranteed>>
  58:     0x7f97638e58b8 - rustc_span[fd000e025c1fef5b]::with_source_map::<core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>, rustc_interface[58e4822cc60d2a6c]::interface::run_compiler<core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>, rustc_driver[8fc339cf4408bec4]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  59:     0x7f97638e53a5 - <scoped_tls[2f862aa259e87453]::ScopedKey<rustc_span[fd000e025c1fef5b]::SessionGlobals>>::set::<rustc_interface[58e4822cc60d2a6c]::interface::run_compiler<core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>, rustc_driver[8fc339cf4408bec4]::run_compiler::{closure#1}>::{closure#0}, core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>
  60:     0x7f97638e4992 - std[14b7645e29e8dad4]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[58e4822cc60d2a6c]::util::run_in_thread_pool_with_globals<rustc_interface[58e4822cc60d2a6c]::interface::run_compiler<core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>, rustc_driver[8fc339cf4408bec4]::run_compiler::{closure#1}>::{closure#0}, core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>
  61:     0x7f9763f1bc1a - <<std[14b7645e29e8dad4]::thread::Builder>::spawn_unchecked_<rustc_interface[58e4822cc60d2a6c]::util::run_in_thread_pool_with_globals<rustc_interface[58e4822cc60d2a6c]::interface::run_compiler<core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>, rustc_driver[8fc339cf4408bec4]::run_compiler::{closure#1}>::{closure#0}, core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[486592e7c49a8aa]::result::Result<(), rustc_errors[5442e185e098f882]::ErrorGuaranteed>>::{closure#1} as core[486592e7c49a8aa]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  62:     0x7f976139b983 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hdbff13d45d6b3b01
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/alloc/src/boxed.rs:2000:9
  63:     0x7f976139b983 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h1e5384a2b7a0037a
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/alloc/src/boxed.rs:2000:9
  64:     0x7f976139b983 - std::sys::unix::thread::Thread::new::thread_start::h4b8540c4f94d9763
                               at /rustc/0468a00ae3fd6ef1a6a0f9eaf637d7aa9e604acc/library/std/src/sys/unix/thread.rs:108:17
  65:     0x7f976125cea7 - start_thread
  66:     0x7f976117aa2f - clone
  67:                0x0 - <unknown>

error: internal compiler error: unexpected panic

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 1.68.0-nightly (0468a00ae 2022-12-17) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [type_op_normalize_ty] normalizing `[async fn body@src/main.rs:9:1: 9:20]`
#1 [mir_borrowck] borrow-checking `ouroboros_impl_s::<impl at src/main.rs:9:1: 9:20>::build::{closure#0}`
#2 [mir_borrowck] borrow-checking `ouroboros_impl_s::<impl at src/main.rs:9:1: 9:20>::build`
#3 [type_of] computing type of `ouroboros_impl_s::<impl at src/main.rs:9:1: 9:20>::build::{opaque#0}`
#4 [check_mod_item_types] checking item types in module `ouroboros_impl_s`
#5 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `playground`
```

Searching the error on open issues only shows [this issue](https://github.com/rust-lang/rust/issues/83085), but I’m not sure whether consts are involved here, too. Ouroboros does generate quite some code… someone (maybe me myself at a later date) would need to expand the macro and search for the relevant bit that causes the ICE. I.e. @rustbot label E-needs-mcve. With a reduced example, we can better judge if this could be a duplicate, and we could also more easily check whether this is a regression, and if yes, where/when.

@rustbot label A-incr-comp