[Nightly] internal compiler error: unexpected panic

[Skarlett]

Short summary:

This code holds a HashMap that contains "jobs", pushes them to be executed in tokio::spawn and sends the return value into mspc::channel (Tokio), finally it produces more jobs, and returns them from the JoinHandle to be appended back into the original HashMap mentioned.

I expected rust to let me know if this proceedure is legal (Appears so) by running cargo check. It returns a compiler Error

EDIT: Corrected summary

use std::{
    time::{Instant, Duration},
    collections::HashMap,
};

use tokio::{
    task::JoinHandle,
    sync::mpsc
};

use async_trait::async_trait;


// Command run on (CRON)
#[async_trait]
pub trait CRON<R>: Sized {
    /// Run function, and then append to parent if more jobs are needed
    async fn exec(self) -> (R, Vec<Self>);
    /// check if command should be ran
    fn check(&self) -> bool;
}


pub struct Scheduler<T, R>
{
    val_tx: mpsc::Sender<R>,
    commands: HashMap<uuid::Uuid, T>,
    handles: Vec<JoinHandle<Vec<T>>>
}

impl<T, R> Scheduler<T, R>
where
    R: Sync + Send + Copy + 'static,
    T: CRON<R> + Sync + Send + 'static,
{
    // COMPILER ERROR - Start 
    fn run_tasks(&mut self) {
        let commands = self.commands.clone();

        for (id, command) in commands {
            if command.check() {       
                let mut vtx = self.val_tx.clone();

                match self.commands.remove(&id) {
                    Some(job) => self.handles.push(
                        tokio::spawn(async move {
                            let (v, jobs) = job.exec().await;
                            vtx.send(v).await;
                            jobs
                    })),
                    
                    None => {} // Add error handle?
                }
            }
        }
    }
    // COMPILER ERROR - End
    fn new() -> (Self, mpsc::Receiver<R>) {
        unimplemented!()
    }
}


struct A {}

#[async_trait]
impl CRON<()> for A {
    async fn exec(self) -> ((), Vec<Self>) {
        ((), vec![])
    }

    fn check(&self) -> bool {
        true
    }
}

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/librustc_typeck/check/method/suggest.rs:550:46

stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1053
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1428
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: rustc_driver::report_ice
  11: <alloc::boxed::Box<F> as core::ops::function::Fn<A>>::call
             at /rustc/75cf41afb468152611212271bae026948cd3ba46/src/liballoc/boxed.rs:1031
  12: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter::{{closure}}::{{closure}}
             at /rustc/75cf41afb468152611212271bae026948cd3ba46/src/libproc_macro/bridge/client.rs:305
  13: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:474
  14: rust_begin_unwind
             at src/libstd/panicking.rs:378
  15: core::panicking::panic_fmt
             at src/libcore/panicking.rs:85
  16: core::panicking::panic
             at src/libcore/panicking.rs:52
  17: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
  18: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T,I>>::from_iter
  19: rustc_typeck::check::method::suggest::<impl rustc_typeck::check::FnCtxt>::report_method_error
  20: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  21: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  22: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_coercable_to_type
  23: rustc_typeck::check::FnCtxt::check_decl_local
  24: rustc_typeck::check::FnCtxt::check_stmt
  25: rustc_typeck::check::FnCtxt::check_block_with_expected
  26: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  27: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  28: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_return_expr
  29: rustc_typeck::check::check_fn
  30: rustc::ty::context::GlobalCtxt::enter_local
  31: rustc_typeck::check::typeck_tables_of
  32: rustc::ty::query::__query_compute::typeck_tables_of
  33: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::typeck_tables_of>::compute
  34: rustc::dep_graph::graph::DepGraph::with_task_impl
  35: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  36: rustc_typeck::check::typeck_tables_of
  37: rustc::ty::query::__query_compute::typeck_tables_of
  38: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::typeck_tables_of>::compute
  39: rustc::dep_graph::graph::DepGraph::with_task_impl
  40: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  41: rustc_typeck::collect::type_of::type_of
  42: rustc::ty::query::__query_compute::type_of
  43: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::type_of>::compute
  44: rustc::dep_graph::graph::DepGraph::with_task_impl
  45: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  46: rustc_hir::intravisit::walk_expr
  47: rustc_hir::intravisit::walk_expr
  48: rustc_hir::intravisit::walk_expr
  49: rustc_hir::intravisit::walk_expr
  50: rustc_hir::intravisit::walk_expr
  51: rustc_hir::intravisit::walk_block
  52: rustc_hir::intravisit::walk_expr
  53: <rustc_typeck::collect::CollectItemTypesVisitor as rustc_hir::intravisit::Visitor>::visit_impl_item
  54: rustc::hir::map::Map::visit_item_likes_in_module
  55: rustc_typeck::collect::collect_mod_item_types
  56: rustc::ty::query::__query_compute::collect_mod_item_types
  57: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::collect_mod_item_types>::compute
  58: rustc::dep_graph::graph::DepGraph::with_task_impl
  59: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  60: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::ensure_query
  61: rustc_typeck::check_crate
  62: rustc_interface::passes::analysis
  63: rustc::ty::query::__query_compute::analysis
  64: rustc::dep_graph::graph::DepGraph::with_task_impl
  65: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  66: rustc::ty::context::tls::enter_global
  67: rustc_interface::interface::run_compiler_in_existing_thread_pool
  68: rustc_ast::attr::with_globals

query stack during panic:
#0 [typeck_tables_of] type-checking `scheduler::manager::Scheduler::<T, R>::run_tasks`
#1 [typeck_item_bodies] type-checking all item bodies
#2 [analysis] running analysis passes on this crate
end of query stack

Meta

rustc 1.43.0-nightly (75cf41a 2020-03-04)
binary: rustc
commit-hash: 75cf41a
commit-date: 2020-03-04
host: x86_64-unknown-linux-gnu
release: 1.43.0-nightly
LLVM version: 9.0

[steffahn]

ICE doesn’t happen on latest nightly. @rustbot modify labels to +E-needs-test.

[steffahn]

Appears to be duplicate of #69725.
@rustbot modify labels: -E-needs-test, -E-needs-mcve.

[Skarlett]

Appears to be duplicate of #69725.
@rustbot modify labels: -E-needs-test, -E-needs-mcve.

Confirmed, applied patches from the lastest nightly fixed it. e82734e