ICE: can't type-check body: glacier fixed/78721.rs

[matthiaskrgr]

Code

code from glacier fixed/78721.rs

#![feature(impl_trait_in_bindings)]

struct Bug {
    V1: [(); {
        let f: impl core::future::Future<Output = u8> = async { 1 };
        1
    }],
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.50.0-nightly (f5230fbf7 2020-11-16)
binary: rustc
commit-hash: f5230fbf76bafd86ee4376a0e26e551df8d17fec
commit-date: 2020-11-16
host: x86_64-unknown-linux-gnu
release: 1.50.0-nightly

Error output

rustc fixed/78721.rs

error: expected identifier, found `1`
 --> ./78721.rs:5:65
  |
5 |         let f: impl core::future::Future<Output = u8> = async { 1 };
  |                                                         -----   ^ expected identifier
  |                                                         |
  |                                                         `async` blocks are only allowed in the 2018 edition
  |
  = help: set `edition = "2018"` in `Cargo.toml`
  = note: for more on editions, read https://doc.rust-lang.org/edition-guide

warning: the feature `impl_trait_in_bindings` is incomplete and may not be safe to use and/or cause compiler crashes
 --> ./78721.rs:1:12
  |
1 | #![feature(impl_trait_in_bindings)]
  |            ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #63065 <https://github.com/rust-lang/rust/issues/63065> for more information

error: internal compiler error: compiler/rustc_typeck/src/check/mod.rs:489:9: can't type-check body of DefId(0:3 ~ 78721[317d]::Bug)
 --> ./78721.rs:3:1
  |
3 | / struct Bug {
4 | |     V1: [(); {
5 | |         let f: impl core::future::Future<Output = u8> = async { 1 };
6 | |         1
7 | |     }],
8 | | }
  | |_^

thread 'rustc' panicked at 'Box<Any>', /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/compiler/rustc_errors/src/lib.rs:904:9
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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.50.0-nightly (f5230fbf7 2020-11-16) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `Bug`
#1 [type_of] computing type of `Bug::V1::{constant#0}::{opaque#0}`
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted

Backtrace

thread 'rustc' panicked at 'Box<Any>', /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/compiler/rustc_errors/src/lib.rs:904:9
stack backtrace:
   0:     0x7f637d062fa0 - std::backtrace_rs::backtrace::libunwind::trace::h448c56741b6011d3
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/../../backtrace/src/backtrace/libunwind.rs:100:5
   1:     0x7f637d062fa0 - std::backtrace_rs::backtrace::trace_unsynchronized::h2d26397c5720fdbb
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f637d062fa0 - std::sys_common::backtrace::_print_fmt::h720a2f61f75b9f58
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f637d062fa0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h8d62bbfda6d5c836
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7f637d0d236c - core::fmt::write::h1857a60b204f1b6a
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/core/src/fmt/mod.rs:1078:17
   5:     0x7f637d054c02 - std::io::Write::write_fmt::h16a9fe7680ac245c
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/io/mod.rs:1521:15
   6:     0x7f637d067025 - std::sys_common::backtrace::_print::h9ba51a6db618de7d
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7f637d067025 - std::sys_common::backtrace::print::h5f20e41c85e91716
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7f637d067025 - std::panicking::default_hook::{{closure}}::h5b7294ca19e8edab
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/panicking.rs:208:50
   9:     0x7f637d066cc8 - std::panicking::default_hook::hb3948d1f74b6ff4c
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/panicking.rs:227:9
  10:     0x7f637d948e38 - rustc_driver::report_ice::h7d9ce14184308134
  11:     0x7f637d067926 - std::panicking::rust_panic_with_hook::h55d23fef0ad751bc
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/panicking.rs:597:17
  12:     0x7f637e5c102d - std::panicking::begin_panic::{{closure}}::h8ed9a3a33c3cff07
  13:     0x7f637e5c0fc6 - std::sys_common::backtrace::__rust_end_short_backtrace::h12877d695ee54607
  14:     0x7f637e58b3b6 - std::panicking::begin_panic::hf80c83cb05d9e96b
  15:     0x7f637e55e4a5 - rustc_errors::HandlerInner::span_bug::h6fac04d253db2775
  16:     0x7f637e55e770 - rustc_errors::Handler::span_bug::h311f1a863fb84a83
  17:     0x7f637e67e514 - rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}::h90c34eb7069c0e0d
  18:     0x7f637e67e10b - rustc_middle::ty::context::tls::with_opt::{{closure}}::h4f5cedf51880f643
  19:     0x7f637e67e0b2 - rustc_middle::ty::context::tls::with_opt::h1abd1ee9103ab829
  20:     0x7f637e67e419 - rustc_middle::util::bug::opt_span_bug_fmt::h988677b387978718
  21:     0x7f637e67e3d3 - rustc_middle::util::bug::span_bug_fmt::h03690d0821b8588f
  22:     0x7f637e69b08a - rustc_typeck::check::typeck_with_fallback::{{closure}}::h2a0fb83340fba4ce
  23:     0x7f637e69ac16 - rustc_typeck::check::typeck::h40a6a2fbf5762437
  24:     0x7f637e67d07e - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::typeck>::compute::hbad0f7f90880e308
  25:     0x7f637e573a77 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h1630d8019b850f77
  26:     0x7f637e4e4c11 - rustc_data_structures::stack::ensure_sufficient_stack::h65c269314faf280e
  27:     0x7f637e444369 - rustc_query_system::query::plumbing::get_query_impl::hfe85414a1a5ccee1
  28:     0x7f637e6a536f - rustc_typeck::collect::type_of::type_of::h42fbf74ecd2a48fc
  29:     0x7f637e45eb86 - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::type_of>::compute::hae9279cbf2fd8f00
  30:     0x7f637e583c34 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::hc6e75e9c8f7caa60
  31:     0x7f637e4e49b1 - rustc_data_structures::stack::ensure_sufficient_stack::h645165e5d5ff3eff
  32:     0x7f637e3db24f - rustc_query_system::query::plumbing::get_query_impl::h2e3741383e4d3139
  33:     0x7f637e48fc4c - rustc_typeck::check::check::check_item_type::h8867dc9155a10775
  34:     0x7f637e564222 - rustc_middle::hir::map::Map::visit_item_likes_in_module::h7168eb874fb9fd0c
  35:     0x7f637e493b1d - rustc_typeck::check::check::check_mod_item_types::h9a48b787176c4c98
  36:     0x7f637e56058e - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::check_mod_item_types>::compute::h5b43bca885c2b48a
  37:     0x7f637e571717 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h0022a71a2a880b88
  38:     0x7f637e4eabd4 - rustc_data_structures::stack::ensure_sufficient_stack::hbfdcb494e19b13d3
  39:     0x7f637e4125f5 - rustc_query_system::query::plumbing::get_query_impl::h9da7036e49fcf602
  40:     0x7f637e44627e - rustc_query_system::query::plumbing::ensure_query_impl::h310784e0cb080e9e
  41:     0x7f637e566e74 - rustc_session::utils::<impl rustc_session::session::Session>::time::h3ca5e6132e41bfe6
  42:     0x7f637e5d998f - rustc_typeck::check_crate::h603c10bbe6bfd147
  43:     0x7f637db740c2 - rustc_interface::passes::analysis::h0297dc70c5f42ca2
  44:     0x7f637d97eb82 - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute::h483a2b5cb9981507
  45:     0x7f637d94c2d7 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h5dab9677a1869822
  46:     0x7f637d95d080 - rustc_data_structures::stack::ensure_sufficient_stack::hef1bfd0aeb694af5
  47:     0x7f637d8f18a0 - rustc_query_system::query::plumbing::get_query_impl::hc8aa257a6f276f4a
  48:     0x7f637d981fff - rustc_interface::passes::QueryContext::enter::hf64e301c55abd329
  49:     0x7f637d95ac7e - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::ha4de22cb0dda795a
  50:     0x7f637d8e6f57 - rustc_span::with_source_map::h29633e90c8bdca16
  51:     0x7f637d955ca1 - scoped_tls::ScopedKey<T>::set::hb520569c8597e8d2
  52:     0x7f637d95de65 - std::sys_common::backtrace::__rust_begin_short_backtrace::hc0d91feb93491fb8
  53:     0x7f637d8c9b28 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h425334629854e612
  54:     0x7f637d0768ba - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9e7afb7a0a438236
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/alloc/src/boxed.rs:1307:9
  55:     0x7f637d0768ba - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h70c646c4271337a1
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/alloc/src/boxed.rs:1307:9
  56:     0x7f637d0768ba - std::sys::unix::thread::Thread::new::thread_start::h35d2b8d36f210d02
                               at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/sys/unix/thread.rs:71:17
  57:     0x7f637cf6f3e9 - start_thread
  58:     0x7f637ce8c293 - __GI___clone
  59:                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 1.50.0-nightly (f5230fbf7 2020-11-16) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `Bug`
#1 [type_of] computing type of `Bug::V1::{constant#0}::{opaque#0}`
#2 [check_mod_item_types] checking item types in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted

[fanninpm]

Playground link of example

[matthiaskrgr]

lol, this crashes stable rustc compilers all the way down to 1.44, but ONLY WITH the feature gate. 😆
If I remove the feature gate, there is a proper compiler error.

@rustbot modify labels: +regression-from-stable-to-stable

[matthiaskrgr]

The ICE happens since 1.42

[fanninpm]

After further review, I can confirm that this does cause an ICE with rustc 1.50.0-nightly (1f5bc17 2020-12-19) on macOS 10.15. However, both the playground, running 1.50.0-nightly (2020-12-03 5be3f9f) as of this comment, and (for some weird reason) running glacier locally do not cause an ICE. I will note this in an upcoming PR to glacier.

[apiraino]

Assigning P-medium as discussed as part of the Prioritization Working Group procedure and removing I-prioritize.

[digama0]

Was going to report this but it looks like a duplicate of this bug. In any case, here's a different reproducer:

#![feature(impl_trait_in_bindings)]
const _: impl Fn() = async { 0 };
fn main() {}

Compiler output

   Compiling playground v0.0.1 (/playground)
warning: the feature `impl_trait_in_bindings` is incomplete and may not be safe to use and/or cause compiler crashes
 --> src/main.rs:1:12
  |
1 | #![feature(impl_trait_in_bindings)]
  |            ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #63065 <https://github.com/rust-lang/rust/issues/63065> for more information

error[E0277]: expected a `Fn<()>` closure, found `impl Future`
 --> src/main.rs:2:10
  |
2 | const _: impl Fn() = async { 0 };
  |          ^^^^^^^^^ expected an `Fn<()>` closure, found `impl Future`
  |
  = help: the trait `Fn<()>` is not implemented for `impl Future`
  = note: wrap the `impl Future` in a closure with no arguments: `|| { /* code */ }`

error: internal compiler error: compiler/rustc_mir/src/borrow_check/universal_regions.rs:533:26: expected defining type for `DefId(0:5 ~ playground[b426]::_::{closure#0})`: `[type error]`
 --> src/main.rs:2:28
  |
2 | const _: impl Fn() = async { 0 };
  |                            ^^^^^

thread 'rustc' panicked at 'Box<Any>', /rustc/6d395a1c2946c79966490f5b1e6e619d3a713e6b/library/std/src/panic.rs:59:5
stack backtrace:
   0: std::panicking::begin_panic
   1: std::panic::panic_any
   2: rustc_errors::HandlerInner::span_bug
   3: rustc_errors::Handler::span_bug
   4: rustc_middle::ty::context::tls::with_opt
   5: rustc_middle::util::bug::opt_span_bug_fmt
   6: rustc_middle::util::bug::span_bug_fmt
   7: rustc_mir::borrow_check::universal_regions::UniversalRegions::new
   8: rustc_mir::borrow_check::nll::replace_regions_in_mir
   9: rustc_mir::borrow_check::do_mir_borrowck
  10: rustc_infer::infer::InferCtxtBuilder::enter
  11: rustc_mir::borrow_check::mir_borrowck
  12: core::ops::function::FnOnce::call_once
  13: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  14: rustc_data_structures::stack::ensure_sufficient_stack
  15: rustc_query_system::query::plumbing::force_query_with_job
  16: rustc_query_system::query::plumbing::get_query_impl
  17: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
  18: rustc_typeck::collect::type_of::find_opaque_ty_constraints::ConstraintLocator::check
  19: <rustc_typeck::collect::type_of::find_opaque_ty_constraints::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_expr
  20: rustc_hir::intravisit::walk_expr
  21: rustc_hir::intravisit::Visitor::visit_nested_body
  22: rustc_typeck::collect::type_of::type_of
  23: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  24: rustc_data_structures::stack::ensure_sufficient_stack
  25: rustc_query_system::query::plumbing::force_query_with_job
  26: rustc_query_system::query::plumbing::get_query_impl
  27: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::type_of
  28: rustc_typeck::check::check::check_item_type
  29: rustc_middle::hir::map::Map::visit_item_likes_in_module
  30: rustc_typeck::check::check::check_mod_item_types
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  32: rustc_query_system::query::plumbing::force_query_with_job
  33: rustc_query_system::query::plumbing::get_query_impl
  34: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
  35: rustc_session::utils::<impl rustc_session::session::Session>::time
  36: rustc_typeck::check_crate
  37: rustc_interface::passes::analysis
  38: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  39: rustc_data_structures::stack::ensure_sufficient_stack
  40: rustc_query_system::query::plumbing::force_query_with_job
  41: rustc_query_system::query::plumbing::get_query_impl
  42: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  43: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  44: rustc_span::with_source_map
  45: rustc_interface::interface::create_compiler_and_run
  46: scoped_tls::ScopedKey<T>::set
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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.54.0-nightly (6d395a1c2 2021-05-13) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [mir_borrowck] borrow-checking `_::{closure#0}`
#1 [type_of] computing type of `_::{opaque#0}`
#2 [check_mod_item_types] checking item types in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted

For more information about this error, try `rustc --explain E0277`.
error: could not compile `playground`

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