ICE: Where clause ... was applicable to ... but now is not in `compiler/rustc_trait_selection/src/traits/select/confirmation.rs`

[Naserume]

Code

(original code. over 100 lines)

trait BufMut {}
struct Bytes;
struct BytesMut;

pub trait Future {
    type Item;
}

pub trait Service {
    type Response;
    type Future: Future<Item = Self::Response>;
}

pub trait ThriftService<F>:
    Service<
        Response = FramingEncoded<F>,
        Future = Box<Future<Item = FramingEncodedFinal<F>>>,
    >
where
    F: Framing,
{
    fn get_service(
        &self,
    ) -> &Service<
        Response = Self::Response,
        Future = Self::Future,
    >;
}

pub trait BufMutExt: BufMut {
    type Final;
}

impl BufMutExt for BytesMut {
    type Final = Bytes;
}

pub type FramingEncoded<F> = <F as Framing>::EncBuf;
pub type FramingEncodedFinal<F> = <<F as Framing>::EncBuf as BufMutExt>::Final;

pub trait Framing {
    type EncBuf: BufMut;
}

pub struct SRHeaderTransport;
impl Framing for SRHeaderTransport {
    type EncBuf = BytesMut;
}

pub type BoxService<H> = Box<
    ThriftService<
            SRHeaderTransport,
            Response = Bytes,
            Future = Box<Future<Item = Bytes>>,
        >,
>;

use std::pin::Pin;
use std::task::*;

pub trait Stream {
    type Item;

    fn poll_next(self: Pin<&mut Self>) -> Poll<Option<Self::Item>>;
}

pub trait FnOnce1<A> {
    type Output;
    fn call_once(self, arg: A) -> Self::Output;
}

impl<T, A, R> FnOnce1<A> for T
where
    T: FnOnce(A) -> R,
{
    type Output = R;
    fn call_once(self, arg: A) -> R {
        self(arg)
    }
}

pub trait FnMut1<A>: FnOnce1<A> {
    fn call_mut(&mut self, arg: A) -> Self::Output;
}


struct Map<St, F>(St, F);

impl<St, F> Stream for Map<St, F>
where
    St: Stream,
    F: FnMut1<BoxService>,
{
    type Item = F::Output;

    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        todo!()
    }
}
fn main() {}

Meta

rustc --version --verbose:

rustc 1.81.0-nightly (bcf94dec5 2024-06-23)
binary: rustc
commit-hash: bcf94dec5ba6838e435902120c0384c360126a26
commit-date: 2024-06-23
host: x86_64-apple-darwin
release: 1.81.0-nightly
LLVM version: 18.1.7

Error output

Output

warning: trait objects without an explicit `dyn` are deprecated
  --> ./9079C.rs:17:22
   |
17 |         Future = Box<Future<Item = FramingEncodedFinal<F>>>,
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
   = note: `#[warn(bare_trait_objects)]` on by default
help: if this is an object-safe trait, use `dyn`
   |
17 |         Future = Box<dyn Future<Item = FramingEncodedFinal<F>>>,
   |                      +++

error[E0277]: the trait bound `<F as Framing>::EncBuf: BufMutExt` is not satisfied
  --> ./9079C.rs:14:1
   |
14 | / pub trait ThriftService<F>:
15 | |     Service<
16 | |         Response = FramingEncoded<F>,
17 | |         Future = Box<Future<Item = FramingEncodedFinal<F>>>,
18 | |     >
   | |_____^ the trait `BufMutExt` is not implemented for `<F as Framing>::EncBuf`
   |
help: consider further restricting the associated type
   |
20 |     F: Framing, <F as Framing>::EncBuf: BufMutExt
   |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

error[E0277]: the trait bound `<F as Framing>::EncBuf: BufMutExt` is not satisfied
  --> ./9079C.rs:14:1
   |
14 | / pub trait ThriftService<F>:
15 | |     Service<
16 | |         Response = FramingEncoded<F>,
17 | |         Future = Box<Future<Item = FramingEncodedFinal<F>>>,
...  |
27 | |     >;
28 | | }
   | |_^ the trait `BufMutExt` is not implemented for `<F as Framing>::EncBuf`
   |
help: consider further restricting the associated type
   |
20 |     F: Framing, <F as Framing>::EncBuf: BufMutExt
   |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

warning: trait objects without an explicit `dyn` are deprecated
  --> ./9079C.rs:24:11
   |
24 |       ) -> &Service<
   |  ___________^
25 | |         Response = Self::Response,
26 | |         Future = Self::Future,
27 | |     >;
   | |_____^
   |
   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
help: if this is an object-safe trait, use `dyn`
   |
24 |     ) -> &dyn Service<
   |           +++

error[E0277]: the trait bound `BytesMut: BufMut` is not satisfied
  --> ./9079C.rs:34:20
   |
34 | impl BufMutExt for BytesMut {
   |                    ^^^^^^^^ the trait `BufMut` is not implemented for `BytesMut`
   |
help: this trait has no implementations, consider adding one
  --> ./9079C.rs:1:1
   |
1  | trait BufMut {}
   | ^^^^^^^^^^^^
note: required by a bound in `BufMutExt`
  --> ./9079C.rs:30:22
   |
30 | pub trait BufMutExt: BufMut {
   |                      ^^^^^^ required by this bound in `BufMutExt`

error[E0277]: the trait bound `BytesMut: BufMut` is not satisfied
  --> ./9079C.rs:47:19
   |
47 |     type EncBuf = BytesMut;
   |                   ^^^^^^^^ the trait `BufMut` is not implemented for `BytesMut`
   |
help: this trait has no implementations, consider adding one
  --> ./9079C.rs:1:1
   |
1  | trait BufMut {}
   | ^^^^^^^^^^^^
note: required by a bound in `Framing::EncBuf`
  --> ./9079C.rs:42:18
   |
42 |     type EncBuf: BufMut;
   |                  ^^^^^^ required by this bound in `Framing::EncBuf`

warning: trait objects without an explicit `dyn` are deprecated
  --> ./9079C.rs:51:5
   |
51 | /     ThriftService<
52 | |             SRHeaderTransport,
53 | |             Response = Bytes,
54 | |             Future = Box<Future<Item = Bytes>>,
55 | |         >,
   | |_________^
   |
   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
help: if this is an object-safe trait, use `dyn`
   |
51 |     dyn ThriftService<
   |     +++

warning: trait objects without an explicit `dyn` are deprecated
  --> ./9079C.rs:54:26
   |
54 |             Future = Box<Future<Item = Bytes>>,
   |                          ^^^^^^^^^^^^^^^^^^^^
   |
   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
help: if this is an object-safe trait, use `dyn`
   |
54 |             Future = Box<dyn Future<Item = Bytes>>,
   |                          +++

error[E0091]: type parameter `H` is never used
  --> ./9079C.rs:50:21
   |
50 | pub type BoxService<H> = Box<
   |                     ^ unused type parameter
   |
   = help: consider removing `H` or referring to it in the body of the type alias
   = help: if you intended `H` to be a const parameter, use `const H: /* Type */` instead

error[E0107]: missing generics for type alias `BoxService`
  --> ./9079C.rs:92:15
   |
92 |     F: FnMut1<BoxService>,
   |               ^^^^^^^^^^ expected 1 generic argument
   |
note: type alias defined here, with 1 generic parameter: `H`
  --> ./9079C.rs:50:10
   |
50 | pub type BoxService<H> = Box<
   |          ^^^^^^^^^^ -
help: add missing generic argument
   |
92 |     F: FnMut1<BoxService<H>>,
   |                         +++

error[E0277]: the trait bound `<F as Framing>::EncBuf: BufMutExt` is not satisfied
  --> ./9079C.rs:22:5
   |
22 | /     fn get_service(
23 | |         &self,
24 | |     ) -> &Service<
25 | |         Response = Self::Response,
26 | |         Future = Self::Future,
27 | |     >;
   | |______^ the trait `BufMutExt` is not implemented for `<F as Framing>::EncBuf`
   |
help: consider further restricting the associated type
   |
27 |     > where <F as Framing>::EncBuf: BufMutExt;
   |       +++++++++++++++++++++++++++++++++++++++

error[E0050]: method `poll_next` has 2 parameters but the declaration in trait `Stream::poll_next` has 1
  --> ./9079C.rs:96:24
   |
64 |     fn poll_next(self: Pin<&mut Self>) -> Poll<Option<Self::Item>>;
   |                        -------------- trait requires 1 parameter
...
96 |     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected 1 parameter, found 2

error[E0277]: the trait bound `<F as Framing>::EncBuf: BufMutExt` is not satisfied
  --> ./9079C.rs:24:10
   |
24 |       ) -> &Service<
   |  __________^
25 | |         Response = Self::Response,
26 | |         Future = Self::Future,
27 | |     >;
   | |_____^ the trait `BufMutExt` is not implemented for `<F as Framing>::EncBuf`
   |
help: consider further restricting the associated type
   |
27 |     > where <F as Framing>::EncBuf: BufMutExt;
   |       +++++++++++++++++++++++++++++++++++++++

warning: unused variable: `cx`
  --> ./9079C.rs:96:40
   |
96 |     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
   |                                        ^^ help: if this is intentional, prefix it with an underscore: `_cx`
   |
   = note: `#[warn(unused_variables)]` on by default

Backtrace

error: internal compiler error: compiler/rustc_trait_selection/src/traits/select/confirmation.rs:242:17: Where clause `Binder { value: <F as FnOnce1<std::boxed::Box<(dyn ThriftService<SRHeaderTransport, Future = std::boxed::Box<(dyn Future<Item = Bytes> + 'static)>, Future = std::boxed::Box<(dyn Future<Item = Bytes> + 'static)>, Response = Bytes, Response = BytesMut> + 'static)>>>, bound_vars: [] }` was applicable to `Obligation(predicate=Binder { value: TraitPredicate(<F as FnOnce1<std::boxed::Box<dyn ThriftService<SRHeaderTransport, Future = std::boxed::Box<dyn Future<Item = Bytes>>, Future = std::boxed::Box<dyn Future<Item = Bytes>>, Response = Bytes, Response = BytesMut>>>>, polarity:Positive), bound_vars: [] }, depth=0)` but now is not

thread 'rustc' panicked at compiler/rustc_trait_selection/src/traits/select/confirmation.rs:242:17:
Box<dyn Any>
stack backtrace:
   0:        0x10e1e6b43 - <std::sys::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::he71f7af0ddafc64d
   1:        0x10e23225b - core::fmt::write::h30d0e266faff29b6
   2:        0x10e1dcace - std::io::Write::write_fmt::he666ca78eb4b8406
   3:        0x10e1e6931 - std::sys::backtrace::print::h22721f9ab9a2749a
   4:        0x10e1e9709 - std::panicking::default_hook::{{closure}}::h145e29ed875d8021
   5:        0x10e1e948a - std::panicking::default_hook::h5d437c7e6bf0e3b5
   6:        0x11748147c - std[8efa578c02603ef9]::panicking::update_hook::<alloc[135510a28be92df]::boxed::Box<rustc_driver_impl[63f2171535a6fe49]::install_ice_hook::{closure#0}>>::{closure#0}
   7:        0x10e1ea326 - std::panicking::rust_panic_with_hook::h6889093a56e48d04
   8:        0x1174f0337 - std[8efa578c02603ef9]::panicking::begin_panic::<rustc_errors[8995f93e9c4bcc9a]::ExplicitBug>::{closure#0}
   9:        0x1174dc949 - std[8efa578c02603ef9]::sys::backtrace::__rust_end_short_backtrace::<std[8efa578c02603ef9]::panicking::begin_panic<rustc_errors[8995f93e9c4bcc9a]::ExplicitBug>::{closure#0}, !>
  10:        0x11bee2f09 - std[8efa578c02603ef9]::panicking::begin_panic::<rustc_errors[8995f93e9c4bcc9a]::ExplicitBug>
  11:        0x117502276 - <rustc_errors[8995f93e9c4bcc9a]::diagnostic::BugAbort as rustc_errors[8995f93e9c4bcc9a]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:        0x11819c95e - rustc_middle[4384e439927f71dd]::util::bug::opt_span_bug_fmt::<rustc_span[aed5394308446158]::span_encoding::Span>::{closure#0}
  13:        0x1181522b7 - rustc_middle[4384e439927f71dd]::ty::context::tls::with_opt::<rustc_middle[4384e439927f71dd]::util::bug::opt_span_bug_fmt<rustc_span[aed5394308446158]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:        0x118151d75 - rustc_middle[4384e439927f71dd]::ty::context::tls::with_context_opt::<rustc_middle[4384e439927f71dd]::ty::context::tls::with_opt<rustc_middle[4384e439927f71dd]::util::bug::opt_span_bug_fmt<rustc_span[aed5394308446158]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:        0x11bfa57eb - rustc_middle[4384e439927f71dd]::util::bug::bug_fmt
  16:        0x11917d658 - <rustc_trait_selection[2bb3b73d2222b57e]::traits::select::SelectionContext>::confirm_candidate
  17:        0x119180f86 - <rustc_trait_selection[2bb3b73d2222b57e]::traits::select::SelectionContext>::poly_select::{closure#0}
  18:        0x1190e7ced - <rustc_trait_selection[2bb3b73d2222b57e]::traits::select::SelectionContext>::select
  19:        0x11916cf75 - rustc_trait_selection[2bb3b73d2222b57e]::traits::project::opt_normalize_projection_term
  20:        0x1190d6772 - rustc_trait_selection[2bb3b73d2222b57e]::traits::project::normalize_projection_ty
  21:        0x119211b7d - rustc_traits[94d294c4931cbf40]::normalize_projection_ty::normalize_canonicalized_projection_ty
  22:        0x118b226b5 - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::normalize_canonicalized_projection_ty::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>
  23:        0x118aeb507 - <rustc_query_impl[a24e9023943e74ab]::query_impl::normalize_canonicalized_projection_ty::dynamic_query::{closure#2} as core[9412a59d758dca42]::ops::function::FnOnce<(rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_type_ir[d9be17c5337dd5fe]::canonical::Canonical<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_type_ir[d9be17c5337dd5fe]::ty_kind::AliasTy<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>>)>>::call_once
  24:        0x118922d6d - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_type_ir[d9be17c5337dd5fe]::canonical::Canonical<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_type_ir[d9be17c5337dd5fe]::ty_kind::AliasTy<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  25:        0x118b7b42c - rustc_query_impl[a24e9023943e74ab]::query_impl::normalize_canonicalized_projection_ty::get_query_non_incr::__rust_end_short_backtrace
  26:        0x118fc002b - rustc_middle[4384e439927f71dd]::query::plumbing::query_get_at::<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_type_ir[d9be17c5337dd5fe]::canonical::Canonical<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_type_ir[d9be17c5337dd5fe]::ty_kind::AliasTy<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>>
  27:        0x1191725f5 - <rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer as rustc_type_ir[d9be17c5337dd5fe]::fold::FallibleTypeFolder<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_fold_ty
  28:        0x118ffc2c1 - <&rustc_middle[4384e439927f71dd]::ty::list::RawList<(), rustc_middle[4384e439927f71dd]::ty::generic_args::GenericArg> as rustc_type_ir[d9be17c5337dd5fe]::fold::TypeFoldable<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer>
  29:        0x1190125fd - <rustc_middle[4384e439927f71dd]::ty::Ty as rustc_type_ir[d9be17c5337dd5fe]::fold::TypeSuperFoldable<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_super_fold_with::<rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer>
  30:        0x11917225d - <rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer as rustc_type_ir[d9be17c5337dd5fe]::fold::FallibleTypeFolder<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_fold_ty
  31:        0x118ffc2c1 - <&rustc_middle[4384e439927f71dd]::ty::list::RawList<(), rustc_middle[4384e439927f71dd]::ty::generic_args::GenericArg> as rustc_type_ir[d9be17c5337dd5fe]::fold::TypeFoldable<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer>
  32:        0x1190125fd - <rustc_middle[4384e439927f71dd]::ty::Ty as rustc_type_ir[d9be17c5337dd5fe]::fold::TypeSuperFoldable<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_super_fold_with::<rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer>
  33:        0x11917225d - <rustc_trait_selection[2bb3b73d2222b57e]::traits::query::normalize::QueryNormalizer as rustc_type_ir[d9be17c5337dd5fe]::fold::FallibleTypeFolder<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt>>::try_fold_ty
  34:        0x1192149dd - rustc_traits[94d294c4931cbf40]::type_op::type_op_normalize_ty
  35:        0x118b1ff9d - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::type_op_normalize_ty::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>
  36:        0x118ad2e1f - <rustc_query_impl[a24e9023943e74ab]::query_impl::type_op_normalize_ty::dynamic_query::{closure#2} as core[9412a59d758dca42]::ops::function::FnOnce<(rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_type_ir[d9be17c5337dd5fe]::canonical::Canonical<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::traits::query::type_op::Normalize<rustc_middle[4384e439927f71dd]::ty::Ty>>>)>>::call_once
  37:        0x11892b2ee - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::DefaultCache<rustc_type_ir[d9be17c5337dd5fe]::canonical::Canonical<rustc_middle[4384e439927f71dd]::ty::context::TyCtxt, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::traits::query::type_op::Normalize<rustc_middle[4384e439927f71dd]::ty::Ty>>>, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  38:        0x118b848d1 - rustc_query_impl[a24e9023943e74ab]::query_impl::type_op_normalize_ty::get_query_non_incr::__rust_end_short_backtrace
  39:        0x1190e2121 - <rustc_middle[4384e439927f71dd]::ty::Ty as rustc_trait_selection[2bb3b73d2222b57e]::traits::query::type_op::normalize::Normalizable>::type_op_method
  40:        0x116e889e5 - <rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::traits::query::type_op::Normalize<rustc_middle[4384e439927f71dd]::ty::Ty>> as rustc_trait_selection[2bb3b73d2222b57e]::traits::query::type_op::TypeOp>::fully_perform
  41:        0x116fa47d1 - <rustc_borrowck[89ec071876429d81]::type_check::TypeChecker>::fully_perform_op::<rustc_middle[4384e439927f71dd]::ty::Ty, rustc_middle[4384e439927f71dd]::ty::ParamEnvAnd<rustc_middle[4384e439927f71dd]::traits::query::type_op::Normalize<rustc_middle[4384e439927f71dd]::ty::Ty>>>
  42:        0x116fb307a - <rustc_borrowck[89ec071876429d81]::type_check::TypeChecker>::equate_normalized_input_or_output
  43:        0x116f6ecad - rustc_borrowck[89ec071876429d81]::type_check::type_check
  44:        0x116f417e8 - rustc_borrowck[89ec071876429d81]::nll::compute_regions
  45:        0x116fc65fa - rustc_borrowck[89ec071876429d81]::do_mir_borrowck
  46:        0x116f82b78 - rustc_borrowck[89ec071876429d81]::mir_borrowck
  47:        0x118b1c6dc - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>
  48:        0x11899939e - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::VecCache<rustc_hir[ae2456c39d7f6170]::hir_id::OwnerId, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  49:        0x118b4686b - rustc_query_impl[a24e9023943e74ab]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  50:        0x117d466b1 - <rustc_middle[4384e439927f71dd]::hir::map::Map>::par_body_owners::<rustc_interface[73216d77aad0c3a5]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
  51:        0x117dda7fc - rustc_interface[73216d77aad0c3a5]::passes::run_required_analyses
  52:        0x117ddccb3 - rustc_interface[73216d77aad0c3a5]::passes::analysis
  53:        0x118b22dec - rustc_query_impl[a24e9023943e74ab]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a24e9023943e74ab]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>
  54:        0x11890249e - rustc_query_system[30bd0146b5104221]::query::plumbing::try_execute_query::<rustc_query_impl[a24e9023943e74ab]::DynamicConfig<rustc_query_system[30bd0146b5104221]::query::caches::SingleCache<rustc_middle[4384e439927f71dd]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a24e9023943e74ab]::plumbing::QueryCtxt, false>
  55:        0x118b2d307 - rustc_query_impl[a24e9023943e74ab]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  56:        0x1174258d7 - <rustc_interface[73216d77aad0c3a5]::queries::QueryResult<&rustc_middle[4384e439927f71dd]::ty::context::GlobalCtxt>>::enter::<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}::{closure#1}::{closure#3}>
  57:        0x11747fc94 - rustc_interface[73216d77aad0c3a5]::interface::run_compiler::<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}>::{closure#1}
  58:        0x11746ec91 - std[8efa578c02603ef9]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_with_globals<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_pool_with_globals<rustc_interface[73216d77aad0c3a5]::interface::run_compiler<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}>::{closure#1}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>
  59:        0x11748a3a6 - <<std[8efa578c02603ef9]::thread::Builder>::spawn_unchecked_<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_with_globals<rustc_interface[73216d77aad0c3a5]::util::run_in_thread_pool_with_globals<rustc_interface[73216d77aad0c3a5]::interface::run_compiler<core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>, rustc_driver_impl[63f2171535a6fe49]::run_compiler::{closure#0}>::{closure#1}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[9412a59d758dca42]::result::Result<(), rustc_span[aed5394308446158]::ErrorGuaranteed>>::{closure#2} as core[9412a59d758dca42]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  60:        0x10e1f352b - std::sys::pal::unix::thread::Thread::new::thread_start::h68d49fa26efc1659
  61:     0x7ff801f5318b - __pthread_start

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 make sure that you have updated to the latest nightly

note: please attach the file at `/Users/Documents/240624-58194.txt` to your bug report

query stack during panic:
#0 [normalize_canonicalized_projection_ty] normalizing `<F as FnOnce1<alloc::boxed::Box<dyn ThriftService<SRHeaderTransport, Future = alloc::boxed::Box<dyn Future<Item = Bytes>>, Future = alloc::boxed::Box<dyn Future<Item = Bytes>>, Response = Bytes, Response = BytesMut>>>>::Output`
#1 [type_op_normalize_ty] normalizing `core::task::poll::Poll<core::option::Option<<F as FnOnce1<alloc::boxed::Box<dyn ThriftService<SRHeaderTransport, Future = alloc::boxed::Box<dyn Future<Item = Bytes>>, Future = alloc::boxed::Box<dyn Future<Item = Bytes>>, Response = Bytes, Response = BytesMut>>>>::Output>>`
end of query stack
error: aborting due to 10 previous errors; 5 warnings emitted

Some errors have detailed explanations: E0050, E0091, E0107, E0277.
For more information about an error, try `rustc --explain E0050`.

[theemathas]

My attempt at minimizing and explaining what's going on:

// Step 1: Create two names for a single type: `Thing` and `AlsoThing`

struct Thing;
struct Dummy;
pub trait DummyTrait {
    type DummyType;
}
impl DummyTrait for Dummy {
    type DummyType = Thing;
}
type AlsoThing = <Dummy as DummyTrait>::DummyType;

// Step 2: Create names for a single trait object type: `TraitObject` and `AlsoTraitObject`

pub trait SomeTrait {
    type Item;
}
type TraitObject = dyn SomeTrait<Item = AlsoThing>;
type AlsoTraitObject = dyn SomeTrait<Item = Thing>;

// Step 3: Force the compiler to check whether the two names are the same type

pub trait Supertrait {
    type Foo;
}
pub trait Subtrait: Supertrait<Foo = TraitObject> {}

pub trait HasOutput<A: ?Sized> {
    type Output;
}

fn foo<F>() -> F::Output
where
    F: HasOutput<dyn Subtrait<Foo = AlsoTraitObject>>,
{
    todo!()
}

Error output

   Compiling playground v0.0.1 (/playground)
error: internal compiler error: compiler/rustc_trait_selection/src/traits/select/confirmation.rs:244:17: Where clause `Binder { value: <F as HasOutput<(dyn Subtrait<Foo = (dyn SomeTrait<Item = Thing> + 'static), Foo = (dyn SomeTrait<Item = Thing> + 'static)> + 'static)>>, bound_vars: [] }` was applicable to `Obligation(predicate=Binder { value: TraitPredicate(<F as HasOutput<dyn Subtrait<Foo = dyn SomeTrait<Item = Thing>, Foo = dyn SomeTrait<Item = Thing>>>>, polarity:Positive), bound_vars: [] }, depth=0)` but now is not

thread 'rustc' panicked at compiler/rustc_trait_selection/src/traits/select/confirmation.rs:244:17:
Box<dyn Any>
stack backtrace:
   0:     0x7f23d7219035 - std::backtrace_rs::backtrace::libunwind::trace::h1a07e5dba0da0cd2
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x7f23d7219035 - std::backtrace_rs::backtrace::trace_unsynchronized::h61b9b8394328c0bc
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f23d7219035 - std::sys_common::backtrace::_print_fmt::h1c5e18b460934cff
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f23d7219035 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e1a1972118942ad
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f23d726829b - core::fmt::rt::Argument::fmt::h07af2b4071d536cd
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/rt.rs:165:63
   5:     0x7f23d726829b - core::fmt::write::hc090a2ffd6b28c4a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/fmt/mod.rs:1157:21
   6:     0x7f23d720dbdf - std::io::Write::write_fmt::h8898bac6ff039a23
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/io/mod.rs:1832:15
   7:     0x7f23d7218e0e - std::sys_common::backtrace::_print::h4e80c5803d4ee35b
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f23d7218e0e - std::sys_common::backtrace::print::ha96650907276675e
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f23d721b779 - std::panicking::default_hook::{{closure}}::h215c2a0a8346e0e0
  10:     0x7f23d721b4bd - std::panicking::default_hook::h207342be97478370
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:298:9
  11:     0x7f23da1161b7 - std[3c8ba8ebcf555201]::panicking::update_hook::<alloc[bfbae7e348dce413]::boxed::Box<rustc_driver_impl[c88438ade88661f4]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f23d721be76 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::ha9c3bc81d312fd83
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2036:9
  13:     0x7f23d721be76 - std::panicking::rust_panic_with_hook::hac8bdceee1e4fe2c
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:799:13
  14:     0x7f23da143b44 - std[3c8ba8ebcf555201]::panicking::begin_panic::<rustc_errors[80cf825e20fac581]::ExplicitBug>::{closure#0}
  15:     0x7f23da1404f6 - std[3c8ba8ebcf555201]::sys_common::backtrace::__rust_end_short_backtrace::<std[3c8ba8ebcf555201]::panicking::begin_panic<rustc_errors[80cf825e20fac581]::ExplicitBug>::{closure#0}, !>
  16:     0x7f23da13bb66 - std[3c8ba8ebcf555201]::panicking::begin_panic::<rustc_errors[80cf825e20fac581]::ExplicitBug>
  17:     0x7f23da14cf01 - <rustc_errors[80cf825e20fac581]::diagnostic::BugAbort as rustc_errors[80cf825e20fac581]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x7f23da5c6b1c - rustc_middle[3ff731b746e7b038]::util::bug::opt_span_bug_fmt::<rustc_span[8c7415e9d33ddd75]::span_encoding::Span>::{closure#0}
  19:     0x7f23da5adc2a - rustc_middle[3ff731b746e7b038]::ty::context::tls::with_opt::<rustc_middle[3ff731b746e7b038]::util::bug::opt_span_bug_fmt<rustc_span[8c7415e9d33ddd75]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7f23da5adacb - rustc_middle[3ff731b746e7b038]::ty::context::tls::with_context_opt::<rustc_middle[3ff731b746e7b038]::ty::context::tls::with_opt<rustc_middle[3ff731b746e7b038]::util::bug::opt_span_bug_fmt<rustc_span[8c7415e9d33ddd75]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7f23d831e740 - rustc_middle[3ff731b746e7b038]::util::bug::bug_fmt
  22:     0x7f23dbf14a30 - <rustc_trait_selection[173dcaf5d960508e]::traits::select::SelectionContext>::poly_select::{closure#0}
  23:     0x7f23dbb2be89 - rustc_trait_selection[173dcaf5d960508e]::traits::project::opt_normalize_projection_type
  24:     0x7f23db9cc1f8 - rustc_traits[32e5563bcf83713]::normalize_projection_ty::normalize_canonicalized_projection_ty
  25:     0x7f23db9cbf77 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::normalize_canonicalized_projection_ty::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>
  26:     0x7f23db8bd6f4 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_type_ir[a145be3c51398263]::canonical::Canonical<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt, rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::ty::sty::AliasTy>>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  27:     0x7f23db8bd3ef - rustc_query_impl[a12402620de91e8]::query_impl::normalize_canonicalized_projection_ty::get_query_non_incr::__rust_end_short_backtrace
  28:     0x7f23db8c0c39 - <rustc_trait_selection[173dcaf5d960508e]::traits::query::normalize::QueryNormalizer as rustc_type_ir[a145be3c51398263]::fold::FallibleTypeFolder<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt>>::try_fold_ty
  29:     0x7f23d8af1906 - rustc_traits[32e5563bcf83713]::type_op::type_op_normalize_ty
  30:     0x7f23dbfbee69 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::type_op_normalize_ty::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>
  31:     0x7f23dbfbee2b - <rustc_query_impl[a12402620de91e8]::query_impl::type_op_normalize_ty::dynamic_query::{closure#2} as core[868bc93c3f2beb33]::ops::function::FnOnce<(rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt, rustc_type_ir[a145be3c51398263]::canonical::Canonical<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt, rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::traits::query::type_op::Normalize<rustc_middle[3ff731b746e7b038]::ty::Ty>>>)>>::call_once
  32:     0x7f23dbfbec0b - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::DefaultCache<rustc_type_ir[a145be3c51398263]::canonical::Canonical<rustc_middle[3ff731b746e7b038]::ty::context::TyCtxt, rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::traits::query::type_op::Normalize<rustc_middle[3ff731b746e7b038]::ty::Ty>>>, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  33:     0x7f23dbfbe9b1 - rustc_query_impl[a12402620de91e8]::query_impl::type_op_normalize_ty::get_query_non_incr::__rust_end_short_backtrace
  34:     0x7f23db792de6 - <rustc_borrowck[e21d1bf4e0a96488]::type_check::TypeChecker>::fully_perform_op::<rustc_middle[3ff731b746e7b038]::ty::Ty, rustc_middle[3ff731b746e7b038]::ty::ParamEnvAnd<rustc_middle[3ff731b746e7b038]::traits::query::type_op::Normalize<rustc_middle[3ff731b746e7b038]::ty::Ty>>>
  35:     0x7f23d8e1851e - rustc_borrowck[e21d1bf4e0a96488]::type_check::type_check
  36:     0x7f23d8e52b31 - rustc_borrowck[e21d1bf4e0a96488]::nll::compute_regions
  37:     0x7f23dc215d04 - rustc_borrowck[e21d1bf4e0a96488]::do_mir_borrowck
  38:     0x7f23dc2070ea - rustc_borrowck[e21d1bf4e0a96488]::mir_borrowck
  39:     0x7f23dc206be3 - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>
  40:     0x7f23db5a2f2d - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::VecCache<rustc_span[8c7415e9d33ddd75]::def_id::LocalDefId, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  41:     0x7f23db5a29ce - rustc_query_impl[a12402620de91e8]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  42:     0x7f23dbe161f9 - rustc_interface[640972162e3c086f]::passes::analysis
  43:     0x7f23dbe15aef - rustc_query_impl[a12402620de91e8]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[a12402620de91e8]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>
  44:     0x7f23dc16f022 - rustc_query_system[4e189ce2c77124d]::query::plumbing::try_execute_query::<rustc_query_impl[a12402620de91e8]::DynamicConfig<rustc_query_system[4e189ce2c77124d]::query::caches::SingleCache<rustc_middle[3ff731b746e7b038]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[a12402620de91e8]::plumbing::QueryCtxt, false>
  45:     0x7f23dc16edc9 - rustc_query_impl[a12402620de91e8]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  46:     0x7f23dc010149 - rustc_interface[640972162e3c086f]::interface::run_compiler::<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}
  47:     0x7f23dbfcdf8b - std[3c8ba8ebcf555201]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>
  48:     0x7f23dbfcdd80 - <<std[3c8ba8ebcf555201]::thread::Builder>::spawn_unchecked_<rustc_interface[640972162e3c086f]::util::run_in_thread_with_globals<rustc_interface[640972162e3c086f]::interface::run_compiler<core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>, rustc_driver_impl[c88438ade88661f4]::run_compiler::{closure#0}>::{closure#1}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[868bc93c3f2beb33]::result::Result<(), rustc_span[8c7415e9d33ddd75]::ErrorGuaranteed>>::{closure#2} as core[868bc93c3f2beb33]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  49:     0x7f23d7225cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h09e5a4c541afa800
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  50:     0x7f23d7225cab - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9c8b03c22f4e7026
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
  51:     0x7f23d7225cab - std::sys::pal::unix::thread::Thread::new::thread_start::h522bc89a54da820a
                               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys/pal/unix/thread.rs:108:17
  52:     0x7f23d7133609 - start_thread
  53:     0x7f23d7056353 - clone
  54:                0x0 - <unknown>

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 1.79.0 (129f3b996 2024-06-10) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
#0 [normalize_canonicalized_projection_ty] normalizing `<F as HasOutput<dyn Subtrait<Foo = dyn SomeTrait<Item = Thing>, Foo = dyn SomeTrait<Item = Thing>>>>::Output`
#1 [type_op_normalize_ty] normalizing `<F as HasOutput<dyn Subtrait<Foo = dyn SomeTrait<Item = Thing>, Foo = dyn SomeTrait<Item = Thing>>>>::Output`
#2 [mir_borrowck] borrow-checking `foo`
#3 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `playground` (lib)

[Noratrieb]

errors with the new solver

error[E0277]: the trait bound `F: HasOutput<(dyn Subtrait<Foo = (dyn SomeTrait<Item = Thing> + 'static)> + 'static)>` is not satisfied
  --> <source>:35:1
   |
35 | / {
36 | |     todo!()
37 | | }
   | |_^ the trait `HasOutput<(dyn Subtrait<Foo = (dyn SomeTrait<Item = Thing> + 'static)> + 'static)>` is not implemented for `F`
   |
help: consider further restricting this bound
   |
34 |     F: HasOutput<dyn Subtrait<Foo = AlsoTraitObject>> + HasOutput<(dyn Subtrait<Foo = (dyn SomeTrait<Item = Thing> + 'static)> + 'static)>,
   |                                                       ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.

<Compilation failed>

[theemathas]

I'd argue that next-solver doesn't fix this, since this code should compile. (Note that the code currently compiles if we replace the AlsoThing definition with type AlsoThing = Thing;)

[lqd]

Looks to bisect to nightly-2023-06-17. It's too old to have perf builds available, so here goes the whole thing:

• Sync rustc_codegen_cranelift #112671
• Rollup of 8 pull requests #112681
• Remove comments from mir-opt MIR dumps #112346
• Add an ensure_sufficient_stack to LateContextAndPass::visit_expr #112673
• Use the relative sysroot path in the linker command line to specify sysroot rlibs #112597
• Rollup of 7 pull requests #112702
• rustdoc: Add search result item types after their name #110688
• Ignore the always part of #[inline(always)] in MIR inlining #112294

[theemathas]

I found a different ICE which has similar code (broken MIR):

#![allow(dead_code)]

// Step 1: Create two names for a single type: `Thing` and `AlsoThing`

struct Thing;
struct Dummy;
trait DummyTrait {
    type DummyType;
}
impl DummyTrait for Dummy {
    type DummyType = Thing;
}
type AlsoThing = <Dummy as DummyTrait>::DummyType;

// Step 2: Create two names for a single trait object type: `TraitObject` and `AlsoTraitObject`

trait SomeTrait<T> {}
type TraitObject = dyn SomeTrait<Thing>;
type AlsoTraitObject = dyn SomeTrait<AlsoThing>;

// Step 3: Force the compiler to check whether the two names are the same type

trait Supertrait {
    type Foo: ?Sized;
    fn do_thing(&self);
}
trait Subtrait: Supertrait<Foo = TraitObject> {}

fn foo(x: &dyn Subtrait<Foo = AlsoTraitObject>) {
    x.do_thing();
}

Error output

   Compiling playground v0.0.1 (/playground)
note: no errors encountered even though delayed bugs were created

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

error: internal compiler error: broken MIR in DefId(0:20 ~ playground[8102]::foo) (_3 = &(*_1)): bad assignment (&'?10 dyn [Binder(Trait(Subtrait), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?11) }), [])] + '?12 = &'?3 dyn [Binder(Trait(Subtrait), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?7) }), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?8) }), [])] + '?9): NoSolution
  --> src/lib.rs:30:5
   |
30 |     x.do_thing();
   |     ^
   |
note: delayed at compiler/rustc_borrowck/src/type_check/mod.rs:1313:21
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxt>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
         4: rustc_borrowck::type_check::type_check
         5: rustc_borrowck::nll::compute_regions
         6: rustc_borrowck::do_mir_borrowck
         7: rustc_borrowck::mir_borrowck
         8: 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]>>
         9: 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, false>
        10: rustc_query_impl::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
        11: rustc_interface::passes::analysis
        12: 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]>>
        13: 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, false>
        14: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
        15: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        16: 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#0}>::{closure#1}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        17: <<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#0}>::{closure#1}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#2} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        18: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
        19: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
        20: std::sys::pal::unix::thread::Thread::new::thread_start
                   at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys/pal/unix/thread.rs:108:17
        21: start_thread
        22: clone
  --> src/lib.rs:30:5
   |
30 |     x.do_thing();
   |     ^

error: internal compiler error: broken MIR in DefId(0:20 ~ playground[8102]::foo) (bb0[0]): equate_normalized_input_or_output: `&'?1 dyn [Binder(Trait(Subtrait), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?0) }), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?0) }), [])] + '?1==&'?6 dyn [Binder(Trait(Subtrait), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?7) }), []), Binder(Projection(ExistentialProjection { def_id: DefId(0:17 ~ playground[8102]::Supertrait::Foo), args: [], term: Term::Ty(dyn [Binder(Trait(SomeTrait<Thing>), [])] + '?8) }), [])] + '?9` failed with `NoSolution`
  --> src/lib.rs:29:1
   |
29 | / fn foo(x: &dyn Subtrait<Foo = AlsoTraitObject>) {
30 | |     x.do_thing();
31 | | }
   | |_^
   |
note: delayed at compiler/rustc_borrowck/src/type_check/input_output.rs:209:17
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxt>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: rustc_borrowck::type_check::type_check
         4: rustc_borrowck::nll::compute_regions
         5: rustc_borrowck::do_mir_borrowck
         6: rustc_borrowck::mir_borrowck
         7: 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]>>
         8: 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, false>
         9: rustc_query_impl::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
        10: rustc_interface::passes::analysis
        11: 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]>>
        12: 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, false>
        13: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
        14: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        15: 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#0}>::{closure#1}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        16: <<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#0}>::{closure#1}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#2} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        17: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
        18: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/boxed.rs:2022:9
        19: std::sys::pal::unix::thread::Thread::new::thread_start
                   at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/sys/pal/unix/thread.rs:108:17
        20: start_thread
        21: clone
  --> src/lib.rs:29:1
   |
29 | / fn foo(x: &dyn Subtrait<Foo = AlsoTraitObject>) {
30 | |     x.do_thing();
31 | | }
   | |_^

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 1.79.0 (129f3b996 2024-06-10) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
end of query stack
error: could not compile `playground` (lib)