ICE: glacier fixed/63279.rs with -Zinstrument-coverage: "at least one span"

[matthiaskrgr]

Code

code from glacier fixed/63279.rs

#![feature(type_alias_impl_trait)]

type Closure = impl FnOnce();

fn c() -> Closure {
    || -> Closure { || () }
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.50.0-nightly (b7ebc6b0c 2020-11-30)
binary: rustc
commit-hash: b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18
commit-date: 2020-11-30
host: x86_64-unknown-linux-gnu
release: 1.50.0-nightly

Error output

error[E0271]: type mismatch resolving `<[closure@./63279.rs:6:5: 6:28] as FnOnce<()>>::Output == ()`
 --> ./63279.rs:3:16
  |
3 | type Closure = impl FnOnce();
  |                ^^^^^^^^^^^^^ expected opaque type, found `()`
  |
  = note: expected opaque type `impl FnOnce<()>`
               found unit type `()`

thread 'rustc' panicked at 'at least one span', compiler/rustc_mir/src/transform/coverage/spans.rs:240:47
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

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 (b7ebc6b0c 2020-11-30) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z instrument-coverage

query stack during panic:
#0 [mir_promoted] processing `c`
#1 [mir_borrowck] borrow-checking `c`
end of query stack
error: aborting due to previous error

For more information about this error, try `rustc --explain E0271`.

Backtrace

error[E0271]: type mismatch resolving `<[closure@./63279.rs:6:5: 6:28] as FnOnce<()>>::Output == ()`
 --> ./63279.rs:3:16
  |
3 | type Closure = impl FnOnce();
  |                ^^^^^^^^^^^^^ expected opaque type, found `()`
  |
  = note: expected opaque type `impl FnOnce<()>`
               found unit type `()`

thread 'rustc' panicked at 'at least one span', compiler/rustc_mir/src/transform/coverage/spans.rs:240:47
stack backtrace:
   0:     0x7f9f9c91ce00 - std::backtrace_rs::backtrace::libunwind::trace::h746c3e9529d524bc
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:     0x7f9f9c91ce00 - std::backtrace_rs::backtrace::trace_unsynchronized::h86340908ff889faa
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f9f9c91ce00 - std::sys_common::backtrace::_print_fmt::h43f85f9b18230404
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f9f9c91ce00 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hc132ae1a5b5aa7cd
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7f9f9c98fb9c - core::fmt::write::hdf023a0036d2a25f
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/core/src/fmt/mod.rs:1078:17
   5:     0x7f9f9c90e972 - std::io::Write::write_fmt::h8580846154bcb66a
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/io/mod.rs:1519:15
   6:     0x7f9f9c920a65 - std::sys_common::backtrace::_print::h7ee55fed88d107a3
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7f9f9c920a65 - std::sys_common::backtrace::print::h54a7d3e52a524177
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7f9f9c920a65 - std::panicking::default_hook::{{closure}}::h60921e857bf55a40
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/panicking.rs:208:50
   9:     0x7f9f9c9205ba - std::panicking::default_hook::hf0f9afb1017317fc
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/panicking.rs:225:9
  10:     0x7f9f9d1b2428 - rustc_driver::report_ice::ha25ae86a5858acc3
  11:     0x7f9f9c921366 - std::panicking::rust_panic_with_hook::h8d66bf42b407aaea
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/panicking.rs:595:17
  12:     0x7f9f9c920e87 - std::panicking::begin_panic_handler::{{closure}}::hde71edcd925d0c5e
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/panicking.rs:497:13
  13:     0x7f9f9c91d2bc - std::sys_common::backtrace::__rust_end_short_backtrace::h8a3c7d6cea578919
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/sys_common/backtrace.rs:141:18
  14:     0x7f9f9c920de9 - rust_begin_unwind
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/panicking.rs:493:5
  15:     0x7f9f9c98bfb1 - core::panicking::panic_fmt::h20225113c4a2f8fd
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/core/src/panicking.rs:92:14
  16:     0x7f9f9c98bb93 - core::option::expect_failed::h8be1ca96ca0d69ca
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/core/src/option.rs:1260:5
  17:     0x7f9f9e580074 - rustc_mir::transform::coverage::spans::CoverageSpans::generate_coverage_spans::hcece797668b17080
  18:     0x7f9f9eaa83bd - <rustc_mir::transform::coverage::InstrumentCoverage as rustc_mir::transform::MirPass>::run_pass::h63163fe939ee6941
  19:     0x7f9f9ea101ad - rustc_mir::transform::run_passes::hde85252c218e451d
  20:     0x7f9f9ea10ff9 - rustc_mir::transform::mir_promoted::hbf030df47a64ef91
  21:     0x7f9f9ea619b1 - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::mir_promoted>::compute::hd22b0a9058b7bb65
  22:     0x7f9f9e88fb53 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task::hff3904454383c89e
  23:     0x7f9f9e9367c8 - rustc_data_structures::stack::ensure_sufficient_stack::he581a4f69947db11
  24:     0x7f9f9e671be1 - rustc_query_system::query::plumbing::get_query_impl::h20d9617555a285f4
  25:     0x7f9f9ea97024 - rustc_mir::borrow_check::mir_borrowck::h8fcfde9d3bc3965f
  26:     0x7f9f9ea69845 - core::ops::function::FnOnce::call_once::hda8d7f4d3e0163df
  27:     0x7f9f9df0871e - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::mir_borrowck>::compute::hd320f4ca41a47c0c
  28:     0x7f9f9ddfbd8b - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task::h7bb286f896f87eb1
  29:     0x7f9f9de08b6b - rustc_data_structures::stack::ensure_sufficient_stack::h065fe39becabf0c8
  30:     0x7f9f9df9ce94 - rustc_query_system::query::plumbing::get_query_impl::hce760a80e897a4cd
  31:     0x7f9f9df2b3f5 - rustc_typeck::collect::type_of::find_opaque_ty_constraints::ConstraintLocator::check::h0cb80a824c4819c8
  32:     0x7f9f9df1a908 - rustc_hir::intravisit::Visitor::visit_nested_item::hed7c8c156cf4fcc3
  33:     0x7f9f9df2aa26 - rustc_typeck::collect::type_of::type_of::h682626abe1bfac66
  34:     0x7f9f9dc91c7f - 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::hbd3126cecae236d0
  35:     0x7f9f9ddfd43d - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task::h92e4440372797f42
  36:     0x7f9f9de0df14 - rustc_data_structures::stack::ensure_sufficient_stack::h60075674c5db35a7
  37:     0x7f9f9df4a9b9 - rustc_query_system::query::plumbing::get_query_impl::h2ad9c960400d3ef4
  38:     0x7f9f9dcc8ce1 - rustc_typeck::check::check::check_item_type::hcc9f9443120a7976
  39:     0x7f9f9dcf4f79 - rustc_middle::hir::map::Map::visit_item_likes_in_module::h31e465be68af3fae
  40:     0x7f9f9dccc4fd - rustc_typeck::check::check::check_mod_item_types::h2044a3471193590e
  41:     0x7f9f9de38f6e - 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::h84e989a4d938b565
  42:     0x7f9f9de01844 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task::hb775ad5fbe2007be
  43:     0x7f9f9de09ed6 - rustc_data_structures::stack::ensure_sufficient_stack::h169f6da446a255f9
  44:     0x7f9f9df8589a - rustc_query_system::query::plumbing::get_query_impl::h98dfa03e3aa1a6ea
  45:     0x7f9f9dfae68e - rustc_query_system::query::plumbing::ensure_query_impl::h8ac6e8d7fa871941
  46:     0x7f9f9de63d3f - rustc_typeck::check_crate::hab874d5f99f602e6
  47:     0x7f9f9d410502 - rustc_interface::passes::analysis::h342855b4d8ce9897
  48:     0x7f9f9d16ef2b - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute::h95ff81a8a73eaff3
  49:     0x7f9f9d1ffc06 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_eval_always_task::h71fd6f4f43205659
  50:     0x7f9f9d20eee6 - rustc_data_structures::stack::ensure_sufficient_stack::h426420634e295fa0
  51:     0x7f9f9d19cb44 - rustc_query_system::query::plumbing::get_query_impl::h59cb47161047ab66
  52:     0x7f9f9d1715fb - rustc_interface::passes::QueryContext::enter::heace2ac35bf577de
  53:     0x7f9f9d20ca65 - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::hcfd2504bb4e8d292
  54:     0x7f9f9d1dad37 - rustc_span::with_source_map::hdf17fa3a4d8fe35b
  55:     0x7f9f9d208e8c - scoped_tls::ScopedKey<T>::set::h5dca480b178bbfab
  56:     0x7f9f9d20ffa5 - std::sys_common::backtrace::__rust_begin_short_backtrace::ha4cbf96baa7e4912
  57:     0x7f9f9d178b4a - core::ops::function::FnOnce::call_once{{vtable.shim}}::he2d69591c700ddc8
  58:     0x7f9f9c93062a - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hea1090dbdcecbf5a
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/alloc/src/boxed.rs:1327:9
  59:     0x7f9f9c93062a - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h8d5723d3912bd325
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/alloc/src/boxed.rs:1327:9
  60:     0x7f9f9c93062a - std::sys::unix::thread::Thread::new::thread_start::hc17a425ca2995724
                               at /rustc/b7ebc6b0c1ba3c27ebb17c0b496ece778ef11e18/library/std/src/sys/unix/thread.rs:71:17
  61:     0x7f9f9c8263e9 - start_thread
  62:     0x7f9f9c743293 - __GI___clone
  63:                0x0 - <unknown>

error: internal compiler error: unexpected panic

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 (b7ebc6b0c 2020-11-30) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z instrument-coverage

query stack during panic:
#0 [mir_promoted] processing `c`
#1 [mir_borrowck] borrow-checking `c`
#2 [type_of] computing type of `Closure::{opaque#0}`
#3 [check_mod_item_types] checking item types in top-level module
#4 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

For more information about this error, try `rustc --explain E0271`.

[matthiaskrgr]

@rustbot label: +A-code-coverage +requires-nightly

[matthiaskrgr]

This ICE also triggers on ~200 files inside the rustc repo.