rustc paniced: DefId::expect_local

[dvdsk]

I ran into a compiler panic while playing around with try streams and dyn.

I can only reproduce the example by keeping some code in a seperate libary. I have not removed a dependency on the futures (0.3.19) as that would mean moving alot of traits into the example. I set up a repo to easily replicate this example here.

Code

// client/src/main.rs
use futures::{Stream, stream};

pub fn main() {}

struct State (Option<Box<dyn Stream<Item = Result<lib::P, lib::E>>>>);

fn stream() {
    Box::pin(stream::unfold(State(None), move |state| async move {
        let stream = lib::unpack_stream().await.unwrap();
        let stream = Box::new(stream);
        state.0 = Some(stream);
        Some(((), state))
    }))
}

with as separate lib

// lib/src/lib.rs
use futures::{stream, StreamExt, TryStream, TryStreamExt};

#[derive(Debug)]
pub enum E {
    Empty,
}
pub struct P;

pub async fn unpack_stream() -> Result<impl TryStream<Ok = P, Error = E>, E> {
    let state = ();

    let stream = stream::try_unfold(state, state_machine);
    // this is needed as try_next needs Pin<TryStream> an TryStream is
    // not implemented for Pin<TryStream>
    Ok(stream.into_stream().boxed())
}

async fn state_machine(_: ()) -> Result<Option<(P, ())>, E> {
    Ok(None)
}

Meta

rustc --version --verbose:

rustc 1.57.0 (f1edd0429 2021-11-29)
binary: rustc
commit-hash: f1edd0429582dd29cccacaf50fd134b05593bd9c
commit-date: 2021-11-29
host: x86_64-unknown-linux-gnu
release: 1.57.0
LLVM version: 13.0.0

Error output

thread 'rustc' panicked at 'DefId::expect_local: `DefId(33:20 ~ lib[5f99]::unpack_stream::{opaque#0}::{opaque#0})`
 isn't local', /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/compiler/rustc_span/src/def_id.rs:234:43

Backtrace

stack backtrace:
   0: rust_begin_unwind
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5
   1: core::panicking::panic_fmt
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14
   2: rustc_middle::ty::error::<impl rustc_middle::ty::context::TyCtxt>::suggest_constraining_opaque_associated_ty
pe
   3: rustc_middle::ty::error::<impl rustc_middle::ty::context::TyCtxt>::note_and_explain_type_err
   4: rustc_infer::infer::error_reporting::<impl rustc_infer::infer::InferCtxt>::note_type_err
   5: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtPrivExt>::report_
projection_error
   6: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtExt>::report_fulf
illment_errors
   7: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_argument_types
   8: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::confirm_builtin_call
   9: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_call
  10: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  11: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  12: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  13: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  14: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_stmt
  15: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_block_with_expected
  16: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  17: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_return_expr
  18: rustc_typeck::check::check::check_fn
  19: rustc_typeck::check::closure::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_closure
  20: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  21: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  22: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_argument_types
  23: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::confirm_builtin_call
  24: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_call
  25: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  26: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  27: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_return_expr
  28: rustc_typeck::check::check::check_fn
  29: rustc_typeck::check::closure::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_closure
  30: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  31: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  32: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_argument_types
  33: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::confirm_builtin_call
  34: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_call
  35: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  36: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  37: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_argument_types
  38: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::confirm_builtin_call
  39: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_call
  40: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  41: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  42: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_block_with_expected
  43: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  44: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_return_expr
  45: rustc_typeck::check::check::check_fn
  46: rustc_infer::infer::InferCtxtBuilder::enter
  47: rustc_typeck::check::typeck
  48: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  49: rustc_data_structures::stack::ensure_sufficient_stack
  50: rustc_query_system::query::plumbing::try_execute_query
  51: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  52: rustc_typeck::check::typeck
  53: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  54: rustc_data_structures::stack::ensure_sufficient_stack
  55: rustc_query_system::query::plumbing::try_execute_query
  56: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  57: <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  58: rustc_data_structures::sync::par_for_each_in
  59: rustc_typeck::check::typeck_item_bodies
  60: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  61: rustc_data_structures::stack::ensure_sufficient_stack
  62: rustc_query_system::query::plumbing::try_execute_query
  63: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
  64: rustc_session::utils::<impl rustc_session::session::Session>::time
  65: rustc_typeck::check_crate
  66: rustc_interface::passes::analysis
  67: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  68: rustc_data_structures::stack::ensure_sufficient_stack
  69: rustc_query_system::query::plumbing::try_execute_query
  70: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  71: rustc_interface::passes::QueryContext::enter
  72: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  73: rustc_span::with_source_map
  74: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[compiler-errors]

I believe this is fixed in #89946. @dvdsk, is it possible to try compiling this code with nightly?

[dvdsk]

The compiler no longer crashes using the current nightly. So this is fixed already :)
(I had tried nightly but now see I had forgotten to update the toolchain.)