ICE: "no errors encountered even though delay_span_bug issued" on tantivy v0.21 in release mode

[aumetra]

Code

The issue occurred when compiling tantivy in release mode.
I'm not sure how the create a good min repr for such a rather complex codebase, but the same error occurs when compiling one of their basic examples in release mode.

https://github.com/quickwit-oss/tantivy/blob/0.21/examples/basic_search.rs

Meta

rustc --version --verbose:

rustc 1.75.0-nightly (e0d7ed1f4 2023-10-01)
binary: rustc
commit-hash: e0d7ed1f453fb54578cc96dfea859b0e7be15016
commit-date: 2023-10-01
host: x86_64-unknown-linux-gnu
release: 1.75.0-nightly
LLVM version: 17.0.2

Error output

error: internal compiler error: broken MIR in Item(DefId(0:7908 ~ tantivy[f4b1]::store::reader::{impl#3}::iter_raw::{closure#2})) (after phase change to runtime-optimized) at bb2[6]:
                                Alias(Opaque, AliasTy { args: [ReErased], def_id: DefId(0:18076 ~ tantivy[f4b1]::store::reader::{impl#3}::block_checkpoints::{opaque#0}) }) does not have fields
  --> /home/aumetra/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/flatten.rs:52:9
   |
52 |         self.inner.next()
   |         ^^^^^^^^^^
   |

rustc ICE output

Backtrace

delayed span bug: broken MIR in Item(DefId(0:7908 ~ tantivy[f4b1]::store::reader::{impl#3}::iter_raw::{closure#2})) (after phase change to runtime-optimized) at bb2[6]:
Alias(Opaque, AliasTy { args: [ReErased], def_id: DefId(0:18076 ~ tantivy[f4b1]::store::reader::{impl#3}::block_checkpoints::{opaque#0}) }) does not have fields
   0: <rustc_errors::HandlerInner>::emit_diagnostic
   1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
   2: <rustc_const_eval::transform::validate::CfgChecker>::fail::<alloc::string::String>
   3: <rustc_const_eval::transform::validate::Validator as rustc_middle::mir::MirPass>::run_pass
   4: rustc_mir_transform::pass_manager::run_passes_inner
   5: rustc_mir_transform::optimized_mir
   6: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::optimized_mir::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
   7: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
   8: rustc_query_impl::query_impl::optimized_mir::get_query_non_incr::__rust_end_short_backtrace
   9: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
  10: <rustc_metadata::rmeta::encoder::EncodeContext>::encode_crate_root
  11: rustc_metadata::rmeta::encoder::encode_metadata
  12: rustc_metadata::fs::encode_and_write_metadata
  13: rustc_interface::passes::start_codegen
  14: <rustc_interface::queries::Queries>::ongoing_codegen
  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#1}>::{closure#0}, 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#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  17: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/e0d7ed1f453fb54578cc96dfea859b0e7be15016/library/alloc/src/boxed.rs:2007:9
  18: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/e0d7ed1f453fb54578cc96dfea859b0e7be15016/library/alloc/src/boxed.rs:2007:9
  19: std::sys::unix::thread::Thread::new::thread_start
             at /rustc/e0d7ed1f453fb54578cc96dfea859b0e7be15016/library/std/src/sys/unix/thread.rs:108:17
  20: <unknown>
  21: <unknown>

[kadiwa4]

Regressed from nightly 2023-09-29 (7b4d9e1) to 2023-09-30 (8ce4540).
@rustbot label: regression-from-stable-to-nightly

[lqd]

This has a similar flavor to #116265, opaque alias, reproduces with c545019 but not its parent a66e334 cc @oli-obk .

[apiraino]

WG-prioritization assigning priority (Zulip discussion).

@rustbot label -I-prioritize +P-high

[Luk-ESC]

Minimized to:

fn checkpoints() -> impl Iterator {
    Some(()).iter().flat_map(|_| std::iter::once(()))
}

fn block_checkpoints() -> impl Iterator {
    checkpoints()
}

fn iter_raw() -> impl Iterator {
    let mut iter = block_checkpoints();

    (0..9).map(move |_| {
        iter.next();
    })
}