Returning Result<T, Box<dyn std::error::Error>> from asynchronous task causes panic in the compiler

[aodhneine]

Code

# Cargo.toml
[package]
name = "issue_test_return_async_std"
version = "0.1.0"
authors = ["aodhneine <aodhneine@protonmail.ch>"]
edition = "2018"

# See more keys and their definitions at
# https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]

[dependencies.tokio]
version = "0.2.21"
features = ["full"]

/* src/main.rs */
type NewResult<T> = Result<T, Box<dyn std::error::Error>>;

#[tokio::main]
async fn main() -> NewResult<()> {
    let handle = tokio::spawn(async move {
	return NewResult::<i32>::Ok(1);
    });
    handle.await?;

    return Ok(());
}

Meta

rustc --version --verbose:

rustc 1.45.0-nightly (f93bb2a50 2020-05-25)
binary: rustc
commit-hash: f93bb2a50b37bc8bafe4d960e2afd839eaa854ed
commit-date: 2020-05-25
host: x86_64-unknown-linux-gnu
release: 1.45.0-nightly
LLVM version: 10.0

Error output

:: cargo build -j16 --verbose
       Fresh unicode-xid v0.2.0
       Fresh cfg-if v0.1.10
       Fresh slab v0.4.2
       Fresh arc-swap v0.4.6
       Fresh lazy_static v1.4.0
       Fresh fnv v1.0.7
       Fresh pin-project-lite v0.1.7
       Fresh bytes v0.5.4
       Fresh futures-core v0.3.5
       Fresh libc v0.2.71
       Fresh proc-macro2 v1.0.18
       Fresh log v0.4.8
       Fresh iovec v0.1.4
       Fresh net2 v0.2.34
       Fresh quote v1.0.6
       Fresh signal-hook-registry v1.2.0
       Fresh num_cpus v1.13.0
       Fresh memchr v2.3.3
       Fresh mio v0.6.22
       Fresh syn v1.0.30
       Fresh mio-uds v0.6.8
       Fresh tokio-macros v0.2.5
       Fresh tokio v0.2.21
   Compiling issue_test_return_async_std v0.1.0 (/home/julia/tmp/issue_test_return_async_std)
     Running `rustc --crate-name issue_test_return_async_std --edition=2018 src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -Cembed-bitcode=no -C debuginfo=2 -C metadata=d603f945a98e8f13 -C extra-filename=-d603f945a98e8f13 --out-dir /home/julia/tmp/issue_test_return_async_std/target/debug/deps -C incremental=/home/julia/tmp/issue_test_return_async_std/target/debug/incremental -L dependency=/home/julia/tmp/issue_test_return_async_std/target/debug/deps --extern tokio=/home/julia/tmp/issue_test_return_async_std/target/debug/deps/libtokio-010447985c854926.rlib`
error: internal compiler error: src/librustc_middle/ich/impls_ty.rs:94: StableHasher: unexpected region '_#13r

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:907:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.45.0-nightly (f93bb2a50 2020-05-25) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

error: aborting due to previous error

error: could not compile `issue_test_return_async_std`.

Caused by:
  process didn't exit successfully: `rustc --crate-name issue_test_return_async_std --edition=2018 src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -Cembed-bitcode=no -C debuginfo=2 -C metadata=d603f945a98e8f13 -C extra-filename=-d603f945a98e8f13 --out-dir /home/julia/tmp/issue_test_return_async_std/target/debug/deps -C incremental=/home/julia/tmp/issue_test_return_async_std/target/debug/incremental -L dependency=/home/julia/tmp/issue_test_return_async_std/target/debug/deps --extern tokio=/home/julia/tmp/issue_test_return_async_std/target/debug/deps/libtokio-010447985c854926.rlib` (exit code: 101)
::

Backtrace

   Compiling issue_test_return_async_std v0.1.0 (/home/julia/tmp/issue_test_return_async_std)
error: internal compiler error: src/librustc_middle/ich/impls_ty.rs:94: StableHasher: unexpected region '_#13r

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:907:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/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:1076
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1537
   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:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: <alloc::boxed::Box<F> as core::ops::function::Fn<A>>::call
             at /home/julia/db/store/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/liballoc/boxed.rs:1071
  12: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter::{{closure}}::{{closure}}
             at /home/julia/db/store/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libproc_macro/bridge/client.rs:318
  13: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:490
  14: std::panicking::begin_panic
  15: rustc_errors::HandlerInner::bug
  16: rustc_errors::Handler::bug
  17: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
  18: rustc_middle::ty::context::tls::with_opt::{{closure}}
  19: rustc_middle::ty::context::tls::with_opt
  20: rustc_middle::util::bug::opt_span_bug_fmt
  21: rustc_middle::util::bug::bug_fmt
  22: rustc_middle::ich::impls_ty::<impl rustc_data_structures::stable_hasher::HashStable<rustc_middle::ich::hcx::StableHashingContext> for rustc_middle::ty::sty::RegionKind>::hash_stable
  23: <T as rustc_query_system::dep_graph::dep_node::DepNodeParams<Ctxt>>::to_fingerprint
  24: rustc_query_system::query::plumbing::get_query_impl
  25: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::suggestions::InferCtxtExt>::suggest_await_before_try
  26: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtExt>::report_selection_error
  27: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtExt>::report_fulfillment_errors
  28: rustc_typeck::check::FnCtxt::check_argument_types
  29: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt>::confirm_builtin_call
  30: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt>::check_call
  31: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  32: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  33: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_coercable_to_type
  34: rustc_typeck::check::FnCtxt::check_decl_local
  35: rustc_typeck::check::FnCtxt::check_stmt
  36: rustc_typeck::check::FnCtxt::check_block_with_expected
  37: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  38: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  39: rustc_typeck::check::FnCtxt::check_block_with_expected
  40: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  41: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  42: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_return_expr
  43: rustc_typeck::check::check_fn
  44: rustc_typeck::check::closure::<impl rustc_typeck::check::FnCtxt>::check_expr_closure
  45: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  46: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  47: rustc_typeck::check::FnCtxt::check_argument_types
  48: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt>::confirm_builtin_call
  49: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt>::check_call
  50: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  51: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  52: rustc_typeck::check::FnCtxt::check_argument_types
  53: rustc_typeck::check::FnCtxt::check_method_argument_types
  54: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  55: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  56: rustc_typeck::check::FnCtxt::check_block_with_expected
  57: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  58: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  59: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_return_expr
  60: rustc_typeck::check::check_fn
  61: rustc_middle::ty::context::GlobalCtxt::enter_local
  62: rustc_typeck::check::typeck_tables_of
  63: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck_tables_of>::compute
  64: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  65: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  66: rustc_query_system::query::plumbing::get_query_impl
  67: rustc_typeck::check::typeck_tables_of
  68: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck_tables_of>::compute
  69: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  70: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  71: rustc_query_system::query::plumbing::get_query_impl
  72: rustc_query_system::query::plumbing::ensure_query_impl
  73: rustc_typeck::check::typeck_item_bodies
  74: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck_item_bodies>::compute
  75: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  76: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  77: rustc_query_system::query::plumbing::get_query_impl
  78: rustc_typeck::check_crate
  79: rustc_interface::passes::analysis
  80: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  81: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  82: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  83: rustc_query_system::query::plumbing::get_query_impl
  84: rustc_middle::ty::context::tls::enter_global
  85: rustc_interface::interface::run_compiler_in_existing_thread_pool
  86: rustc_ast::attr::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.45.0-nightly (f93bb2a50 2020-05-25) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
#0 [typeck_tables_of] type-checking `main`
#1 [typeck_tables_of] type-checking `main::{{closure}}#0`
#2 [typeck_item_bodies] type-checking all item bodies
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

error: could not compile `issue_test_return_async_std`.

To learn more, run the command again with --verbose.

[aodhneine]

Related: tokio-rs/tokio#2588, async-rs/async-std#810.

[jonas-schievink]

Duplicate of #72766, this should be fixed in the current nightly.