ICE "broken MIR ... Field projection specified type ... but actual type is ..." comparing type with type as trait

[teor2345]

There seems to be a bug in the way that Rust compiles Iterator::flat_map(), in release mode, with complex iterators.

It also triggers on other "type" vs "type as trait" comparisons in the compiler, for example unsized-vec fails with:

error: internal compiler error: broken MIR in DropGlue(DefId(2:2141 ~ core[0ec9]::ptr::drop_in_place), Some(unsized_vec::UnsizedVec<dyn std::fmt::Debug>)) (after phase change to runtime-optimized) at bb0[0]:
                                Field projection `(*_1).field[0]` specified type `unsized_vec::inner::unaligned::UnalignedVecInner<dyn std::fmt::Debug>`, but actual type is `<dyn std::fmt::Debug as unsized_vec::inner::UnsizedVecImpl>::Impl`
   --> /home/dev/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:490:1
    |
490 | pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: delayed at compiler/rustc_const_eval/src/transform/validate.rs:229:30

error: internal compiler error: broken MIR in DropGlue(DefId(2:2141 ~ core[0ec9]::ptr::drop_in_place), Some(unsized_vec::UnsizedVec<[i32]>)) (after phase change to runtime-optimized) at bb0[0]:
                                Field projection `(*_1).field[0]` specified type `unsized_vec::inner::aligned::AlignedVecInner<[i32]>`, but actual type is `<[i32] as unsized_vec::inner::UnsizedVecImpl>::Impl`
   --> /home/dev/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:490:1

Code

Related crate code:

Details

pub enum Transaction {
    V5 {
        orchard_shielded_data: Option<ShieldedData>,
    },
}

impl Transaction {
    pub fn orchard_shielded_data(&self) -> Option<&ShieldedData> {
        match self {
            // Maybe Orchard shielded data
            Transaction::V5 {
                orchard_shielded_data,
                ..
            } => orchard_shielded_data.as_ref(),
        }
    }

    pub fn orchard_nullifiers(&self) -> impl Iterator<Item = &Nullifier> {
        self.orchard_shielded_data()
            .into_iter()
            .flat_map(ShieldedData::nullifiers)
    }
}

pub struct ShieldedData {
    pub actions: AtLeastOne<AuthorizedAction>,
}

impl ShieldedData {
    pub fn actions(&self) -> impl Iterator<Item = &Action> {
        self.actions.actions()
    }

    pub fn nullifiers(&self) -> impl Iterator<Item = &Nullifier> {
        self.actions().map(|action| &action.nullifier)
    }
}

impl AtLeastOne<AuthorizedAction> {
    pub fn actions(&self) -> impl Iterator<Item = &Action> {
        self.iter()
            .map(|authorized_action| &authorized_action.action)
    }
}

pub struct AuthorizedAction {
    pub action: Action,
}

pub struct Action {
    pub nullifier: (),
}

pub struct AtLeastOne<T> {
    inner: Vec<T>,
}

impl<T> Deref for AtLeastOne<T> {
    type Target = Vec<T>;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl<T> AsRef<[T]> for AtLeastOne<T> {
    fn as_ref(&self) -> &[T] {
        self.inner.as_ref()
    }
}

impl<T> IntoIterator for AtLeastOne<T> {
    type Item = T;

    type IntoIter = std::vec::IntoIter<T>;

    fn into_iter(self) -> std::vec::IntoIter<T> {
        self.inner.into_iter()
    }
}

Failing code:

impl Transaction {
    pub fn orchard_nullifiers(&self) -> impl Iterator<Item = &Nullifier> {
        self.orchard_shielded_data()
            .into_iter()
            .flat_map(ShieldedData::nullifiers)
    }
}

    let orchard_nullifier_count = block
        .transactions
        .iter()
        .flat_map(|t| t.orchard_nullifiers()) 
        .count();

    for nullifier in prepared.block.orchard_nullifiers() { }

Workaround:

    pub fn orchard_nullifiers(&self) -> impl Iterator<Item = &orchard::Nullifier> {
        let nullifiers: Vec<_> = self
            .transactions
            .iter()
            .flat_map(|transaction| transaction.orchard_nullifiers())
            .collect();

        nullifiers.into_iter()
    }

    let orchard_nullifier_count: usize = block
        .transactions
        .iter()
        .map(|t| t.orchard_nullifiers().into_iter().count())
        .sum();

Meta

Fails from nightly nightly-2022-11-20 onwards, in commit 2f8d804.

rustc --version --verbose:

rustc 1.67.0-nightly (2585bcea0 2022-11-28)
binary: rustc
commit-hash: 2585bcea0bc2a9c42a4be2c1eba5c61137f2b167
commit-date: 2022-11-28
host: x86_64-unknown-linux-gnu
release: 1.67.0-nightly
LLVM version: 15.0.4

I used these commands to bisect the nightly Rust version:

git clone https://github.com/ZcashFoundation/zebra.git
git checkout a763eec9f3
cd zebra-state

cat << EOF > cargo-build-release.sh
#!/usr/bin/env bash
cargo build --release
EOF
chmod +x cargo-build-release.sh

cargo-bisect-rustc --start=2022-11-07 --regress=ice --script=./cargo-build-release.sh

Zebra needs some build dependencies:
https://github.com/ZcashFoundation/zebra#build-instructions

Regression log:
searched nightlies: from nightly-2022-11-07 to nightly-2022-11-29
regressed nightly: nightly-2022-11-20
searched commit range: b833ad5...c5d82ed
regressed commit: 2f8d804

bisected with cargo-bisect-rustc v0.6.4

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

cargo bisect-rustc --regress=ice --script=./cargo-build-release.sh 

Analysis

This might be caused by -C linker-plugin-lto or release builds, but I couldn't find an exact set of flags or a minimal example to reproduce it.

cargo build does not fail, either from the individual crate or workspace directory. But cargo build --release and cargo install --git https://github.com/ZcashFoundation/zebra.git zebrad fail.

I tried commenting out my whole .cargo/config.toml, and it didn't make a difference.

Error output

error: internal compiler error: no errors encountered even though `delay_span_bug` issued                
                                                                                                         
error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:1718 ~ zebra_state[4d
f4]::service::finalized_state::zebra_db::metrics::block_precommit_metrics), const_param_did: None }) (aft
er phase change to runtime-optimized) at bb128[5]:                                                       
                                Field projection `_37.field[0]` specified type `std::iter::adapters::flat
ten::FlattenCompat<std::iter::Map<std::slice::Iter<'_, std::sync::Arc<zebra_chain::transaction::Transacti
on>>, [closure@zebra-state/src/service/finalized_state/zebra_db/metrics.rs:39:19: 39:22]>, std::iter::Fla
tMap<std::option::IntoIter<&zebra_chain::orchard::ShieldedData>, std::iter::Map<std::iter::Map<std::slice
::Iter<'_, zebra_chain::orchard::AuthorizedAction>, [closure@zebra_chain::orchard::shielded_data::<impl z
ebra_chain::serialization::AtLeastOne<zebra_chain::orchard::AuthorizedAction>>::actions::{closure#0}]>, [
closure@zebra_chain::orchard::ShieldedData::nullifiers::{closure#0}]>, for<'a> fn(&'a zebra_chain::orchar
d::ShieldedData) -> impl std::iter::Iterator<Item = &'a zebra_chain::orchard::Nullifier> {zebra_chain::or
chard::ShieldedData::nullifiers}>>`, but actual type is `std::iter::adapters::flatten::FlattenCompat<std:
:iter::Map<std::slice::Iter<'_, std::sync::Arc<zebra_chain::transaction::Transaction>>, [closure@zebra-st
ate/src/service/finalized_state/zebra_db/metrics.rs:39:19: 39:22]>, <std::iter::FlatMap<std::option::Into
Iter<&zebra_chain::orchard::ShieldedData>, std::iter::Map<std::iter::Map<std::slice::Iter<'_, zebra_chain
::orchard::AuthorizedAction>, [closure@zebra_chain::orchard::shielded_data::<impl zebra_chain::serializat
ion::AtLeastOne<zebra_chain::orchard::AuthorizedAction>>::actions::{closure#0}]>, [closure@zebra_chain::o
rchard::ShieldedData::nullifiers::{closure#0}]>, for<'a> fn(&'a zebra_chain::orchard::ShieldedData) -> im
pl std::iter::Iterator<Item = &'a zebra_chain::orchard::Nullifier> {zebra_chain::orchard::ShieldedData::n
ullifiers}> as std::iter::IntoIterator>::IntoIter>`                                                      
  --> zebra-state/src/service/finalized_state/zebra_db/metrics.rs:36:35 
   |                                                                                                     
36 |       let orchard_nullifier_count = block
   |  ___________________________________^
37 | |         .transactions
38 | |         .iter()
39 | |         .flat_map(|t| t.orchard_nullifiers()) 
40 | |         .count();
   | |________________^
   |
   = note: delayed at compiler/rustc_const_eval/src/transform/validate.rs:229:30

error: internal compiler error: broken MIR in Item(WithOptConstParam { did: DefId(0:4282 ~ zebra_state[4d
f4]::service::check::nullifier::no_duplicates_in_finalized_chain), const_param_did: None }) (after phase 
change to runtime-optimized) at bb60[6]:
                                Field projection `(*_128).field[0]` specified type `std::iter::adapters::
flatten::FlattenCompat<std::iter::Map<std::slice::Iter<'_, std::sync::Arc<zebra_chain::transaction::Trans
action>>, [closure@zebra_chain::block::Block::orchard_nullifiers::{closure#0}]>, std::iter::FlatMap<std::
option::IntoIter<&zebra_chain::orchard::ShieldedData>, std::iter::Map<std::iter::Map<std::slice::Iter<'_,
 zebra_chain::orchard::AuthorizedAction>, [closure@zebra_chain::orchard::shielded_data::<impl zebra_chain
::serialization::AtLeastOne<zebra_chain::orchard::AuthorizedAction>>::actions::{closure#0}]>, [closure@ze
bra_chain::orchard::ShieldedData::nullifiers::{closure#0}]>, for<'a> fn(&'a zebra_chain::orchard::Shielde
dData) -> impl std::iter::Iterator<Item = &'a zebra_chain::orchard::Nullifier> {zebra_chain::orchard::Shi
eldedData::nullifiers}>>`, but actual type is `std::iter::adapters::flatten::FlattenCompat<std::iter::Map
<std::slice::Iter<'_, std::sync::Arc<zebra_chain::transaction::Transaction>>, [closure@zebra_chain::block
::Block::orchard_nullifiers::{closure#0}]>, <std::iter::FlatMap<std::option::IntoIter<&zebra_chain::orcha
rd::ShieldedData>, std::iter::Map<std::iter::Map<std::slice::Iter<'_, zebra_chain::orchard::AuthorizedAct
ion>, [closure@zebra_chain::orchard::shielded_data::<impl zebra_chain::serialization::AtLeastOne<zebra_ch
ain::orchard::AuthorizedAction>>::actions::{closure#0}]>, [closure@zebra_chain::orchard::ShieldedData::nu
llifiers::{closure#0}]>, for<'a> fn(&'a zebra_chain::orchard::ShieldedData) -> impl std::iter::Iterator<I
tem = &'a zebra_chain::orchard::Nullifier> {zebra_chain::orchard::ShieldedData::nullifiers}> as std::iter
::IntoIterator>::IntoIter>`
  --> zebra-state/src/service/check/nullifier.rs:48:22
   |
48 |     for nullifier in prepared.block.orchard_nullifiers() {
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: delayed at compiler/rustc_const_eval/src/transform/validate.rs:229:30]

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1609:13

Backtrace

stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
   2: <rustc_errors::HandlerInner>::flush_delayed::<alloc::vec::Vec<rustc_errors::diagnostic::Diagnostic>
, &str>
   3: <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop
   4: core::ptr::drop_in_place::<rustc_session::parse::ParseSess>
   5: core::ptr::drop_in_place::<rustc_session::session::Session>
   6: core::ptr::drop_in_place::<rustc_interface::interface::Compiler>
   7: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interf
ace::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_c
ompiler::{closure#1}>::{closure#0}::{closure#0}>
   8: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler
<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{clos
ure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

note: compiler flags: --crate-type lib -C opt-level=3 -C panic=abort -C linker-plugin-lto -C debuginfo=1 
-C debug-assertions=on

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

query stack during panic:
end of query stack
error: could not compile `zebra-state`

[teor2345]

I found a workaround, but I still couldn't find a minimal example.

[Noratrieb]

Out of the rollup, it was probably caused by #104411? cc @lcnr

[Millione]

I think I encountered the same ICE bug, and still can't find a minimal reproduce example.

Error output

warning: Error finalizing incremental compilation session directory `/data00/home/liujie.roger/rust/git/volo/target/debug/incremental/hello_grpc_server-2r9arx04lojyo/s-gfv6wd3lvx-9bb9z2-working`: No such file or directory (os error 2)

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

error: internal compiler error: broken MIR in DropGlue(DefId(2:2801 ~ core[bc14]::ptr::drop_in_place), Some(volo_grpc::codegen::hyper::proto::h1::dispatch::Server<volo::service::Tower<volo_grpc::server::meta::MetaService<volo_grpc::server::Router>, [closure@volo_grpc::server::Server<volo::layer::Identity>::run<volo::net::Address>::{closure#0}::{closure#0}], volo_grpc::context::ServerContext, http::request::Request<volo_grpc::codegen::hyper::body::body::Body>>, volo_grpc::codegen::hyper::body::body::Body>)) (after phase change to runtime-optimized) at bb0[0]:
                                Field projection `(*_1).field[0]` specified type `std::pin::Pin<std::boxed::Box<std::option::Option<[async block@<volo::service::Tower<volo_grpc::server::meta::MetaService<volo_grpc::server::Router>, [closure@volo_grpc::server::Server<volo::layer::Identity>::run<volo::net::Address>::{closure#0}::{closure#0}], volo_grpc::context::ServerContext, http::request::Request<volo_grpc::codegen::hyper::body::body::Body>> as tower_service::Service<http::request::Request<volo_grpc::codegen::hyper::body::body::Body>>>::call::{closure#0}]>>>`, but actual type is `std::pin::Pin<std::boxed::Box<std::option::Option<<volo::service::Tower<volo_grpc::server::meta::MetaService<volo_grpc::server::Router>, [closure@volo_grpc::server::Server<volo::layer::Identity>::run<volo::net::Address>::{closure#0}::{closure#0}], volo_grpc::context::ServerContext, http::request::Request<volo_grpc::codegen::hyper::body::body::Body>> as volo_grpc::codegen::hyper::service::http::HttpService<volo_grpc::codegen::hyper::body::body::Body>>::Future>>>`
   --> /data00/home/liujie.roger/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:490:1
    |
490 | pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: delayed at compiler/rustc_const_eval/src/transform/validate.rs:229:30

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1609:13
stack backtrace:
   0:     0x7fd67761d20a - std::backtrace_rs::backtrace::libunwind::trace::h5d63982369f255be
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7fd67761d20a - std::backtrace_rs::backtrace::trace_unsynchronized::h3f0ca420a5fce959
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fd67761d20a - std::sys_common::backtrace::_print_fmt::hb06d2f24224d5008
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7fd67761d20a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h3ab5a4a02080cf95
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fd677b2212e - core::fmt::write::h7d275b25684d2f4b
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/core/src/fmt/mod.rs:1208:17
   5:     0x7fd6776114d5 - std::io::Write::write_fmt::habd0270971df3efd
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/io/mod.rs:1682:15
   6:     0x7fd67761cfd5 - std::sys_common::backtrace::_print::h61bb07d45642a6b0
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7fd67761cfd5 - std::sys_common::backtrace::print::h5d41efe8a7680c9e
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7fd67761f33f - std::panicking::default_hook::{{closure}}::he45a8add8cd6c157
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/panicking.rs:267:22
   9:     0x7fd67761f07b - std::panicking::default_hook::h5bdfb218ae8ccf1a
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/panicking.rs:286:9
  10:     0x7fd676864e54 - rustc_driver[9b4589fbd0ca3010]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7fd67761fb3d - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hc626e6f5815a4649
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/alloc/src/boxed.rs:2032:9
  12:     0x7fd67761fb3d - std::panicking::rust_panic_with_hook::haa2a8406479dd255
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/panicking.rs:692:13
  13:     0x7fd67689d8d1 - std[85b9d86509865b2b]::panicking::begin_panic::<rustc_errors[7d36137f8dd089c7]::ExplicitBug>::{closure#0}
  14:     0x7fd67689c196 - std[85b9d86509865b2b]::sys_common::backtrace::__rust_end_short_backtrace::<std[85b9d86509865b2b]::panicking::begin_panic<rustc_errors[7d36137f8dd089c7]::ExplicitBug>::{closure#0}, !>
  15:     0x7fd676894816 - std[85b9d86509865b2b]::panicking::begin_panic::<rustc_errors[7d36137f8dd089c7]::ExplicitBug>
  16:     0x7fd676898026 - std[85b9d86509865b2b]::panic::panic_any::<rustc_errors[7d36137f8dd089c7]::ExplicitBug>
  17:     0x7fd675d7fe86 - <rustc_errors[7d36137f8dd089c7]::HandlerInner>::flush_delayed::<alloc[edfeea1ed307d55e]::vec::Vec<rustc_errors[7d36137f8dd089c7]::diagnostic::Diagnostic>, &str>
  18:     0x7fd675d7f18b - <rustc_errors[7d36137f8dd089c7]::HandlerInner as core[bc14861035b9f032]::ops::drop::Drop>::drop
  19:     0x7fd675ad2a7e - core[bc14861035b9f032]::ptr::drop_in_place::<rustc_session[74924a319b9741d3]::parse::ParseSess>
  20:     0x7fd675ac373f - core[bc14861035b9f032]::ptr::drop_in_place::<rustc_session[74924a319b9741d3]::session::Session>
  21:     0x7fd675ac3470 - core[bc14861035b9f032]::ptr::drop_in_place::<rustc_interface[4869d893f0e6a446]::interface::Compiler>
  22:     0x7fd675ac257e - rustc_span[fe585761646e9245]::with_source_map::<core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>, rustc_interface[4869d893f0e6a446]::interface::run_compiler<core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>, rustc_driver[9b4589fbd0ca3010]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  23:     0x7fd675ac1eb5 - <scoped_tls[88353d2f7a38210b]::ScopedKey<rustc_span[fe585761646e9245]::SessionGlobals>>::set::<rustc_interface[4869d893f0e6a446]::interface::run_compiler<core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>, rustc_driver[9b4589fbd0ca3010]::run_compiler::{closure#1}>::{closure#0}, core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>>
  24:     0x7fd675ac14a2 - std[85b9d86509865b2b]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[4869d893f0e6a446]::util::run_in_thread_pool_with_globals<rustc_interface[4869d893f0e6a446]::interface::run_compiler<core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>, rustc_driver[9b4589fbd0ca3010]::run_compiler::{closure#1}>::{closure#0}, core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>>
  25:     0x7fd675ac11b8 - <<std[85b9d86509865b2b]::thread::Builder>::spawn_unchecked_<rustc_interface[4869d893f0e6a446]::util::run_in_thread_pool_with_globals<rustc_interface[4869d893f0e6a446]::interface::run_compiler<core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>, rustc_driver[9b4589fbd0ca3010]::run_compiler::{closure#1}>::{closure#0}, core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[bc14861035b9f032]::result::Result<(), rustc_errors[7d36137f8dd089c7]::ErrorGuaranteed>>::{closure#1} as core[bc14861035b9f032]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  26:     0x7fd677626d73 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h87f315d78631c89a
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/alloc/src/boxed.rs:2000:9
  27:     0x7fd677626d73 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h44e64edef3723eae
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/alloc/src/boxed.rs:2000:9
  28:     0x7fd677626d73 - std::sys::unix::thread::Thread::new::thread_start::h6b1af1d92f601469
                               at /rustc/2585bcea0bc2a9c42a4be2c1eba5c61137f2b167/library/std/src/sys/unix/thread.rs:108:17
  29:     0x7fd672fcd4a4 - start_thread
                               at /build/glibc-77giwP/glibc-2.24/nptl/pthread_create.c:456
  30:     0x7fd672d0fd0f - __GI___clone
                               at /build/glibc-77giwP/glibc-2.24/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:97
  31:                0x0 - <unknown>

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 1.67.0-nightly (2585bcea0 2022-11-28) 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:
end of query stack

[MilkFather]

Perhaps #105009 shares the same problem? Same regressed nightly build, same ice error ("delay_span_bug" + broken MIR).

[Jules-Bertholet]

unsized-vec also triggers the same ICE upon cargo test, with the same bisection result.

[teor2345]

unsized-vec also triggers the same ICE upon cargo test, with the same bisection result.

Do you have a minimal example?

I had trouble getting one from Zebra, because the error happened when calling a large chain of iterators.

(I've added the specific unsized-vec error message to the description.)