ICE on beta and nightly as result of use of yield in combination with macro call in async block

[olegnn]

This code

fn main() {
    async { yield print!(":C") };
}

(Playground)

produces ICE on current beta and nightly

thread 'rustc' panicked at 'src/librustc/hir/map/hir_id_validator.rs:26: 
ItemLocalIds not assigned densely in ::main[0]. Max ItemLocalId = 14, missing IDs = ["[local_id: 1, node:unknown node (hir_id=HirId { owner: DefIndex(12), local_id: 1 })]"]; seens IDs = ["(HirId { owner: DefIndex(12), local_id: 0 } fn main (hir_id=HirId { owner: DefIndex(12), local_id: 0 }))", "(HirId { owner: DefIndex(12), local_id: 13 } block { ::std::future::from_generator(|| { (/*ERROR*/) }); } (hir_id=HirId { owner: DefIndex(12), local_id: 13 }))", "(HirId { owner: DefIndex(12), local_id: 10 } expr ::std::future::from_generator (hir_id=HirId { owner: DefIndex(12), local_id: 10 }))", "(HirId { owner: DefIndex(12), local_id: 7 } path segment std (hir_id=HirId { owner: DefIndex(12), local_id: 7 }))", "(HirId { owner: DefIndex(12), local_id: 4 } expr { (/*ERROR*/) } (hir_id=HirId { owner: DefIndex(12), local_id: 4 }))", "(HirId { owner: DefIndex(12), local_id: 14 } expr { ::std::future::from_generator(|| { (/*ERROR*/) }); } (hir_id=HirId { owner: DefIndex(12), local_id: 14 }))", "(HirId { owner: DefIndex(12), local_id: 11 } expr ::std::future::from_generator(|| { (/*ERROR*/) }) (hir_id=HirId { owner: DefIndex(12), local_id: 11 }))", "(HirId { owner: DefIndex(12), local_id: 8 } path segment future (hir_id=HirId { owner: DefIndex(12), local_id: 8 }))", "(HirId { owner: DefIndex(12), local_id: 5 } expr || { (/*ERROR*/) } (hir_id=HirId { owner: DefIndex(12), local_id: 5 }))", "(HirId { owner: DefIndex(12), local_id: 2 } expr (/*ERROR*/) (hir_id=HirId { owner: DefIndex(12), local_id: 2 }))", "(HirId { owner: DefIndex(12), local_id: 12 } stmt ::std::future::from_generator(|| { (/*ERROR*/) }); (hir_id=HirId { owner: DefIndex(12), local_id: 12 }))", "(HirId { owner: DefIndex(12), local_id: 9 } path segment from_generator (hir_id=HirId { owner: DefIndex(12), local_id: 9 }))", "(HirId { owner: DefIndex(12), local_id: 6 } path segment  (hir_id=HirId { owner: DefIndex(12), local_id: 6 }))", "(HirId { owner: DefIndex(12), local_id: 3 } block { (/*ERROR*/) } (hir_id=HirId { owner: DefIndex(12), local_id: 3 }))"]', src/librustc/util/bug.rs:37:26
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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.40.0-beta.2 (2a0ba54fa 2019-11-16) running on x86_64-apple-darwin

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

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

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0658`.
error: could not compile `rust-games`.

[nikomatsakis]

Tagging as P-medium and "triaged" for async-await.

Note that yield is unstable.

[estebank]

@Centril the feature is nightly but the ice doesn't require any feature gate to trigger.

[chrissimpkins]

Regression found in the compiler

searched nightlies: from nightly-2019-01-01 to nightly-2020-02-01
regressed nightly: nightly-2019-09-29
searched commits: from 084beb8 to 488381c
regressed commit: f3c8eba
source code: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=956b959a5649adaecb4fe39acef8239d

Instructions

cargo bisect-rustc --start 2019-09-28 --end 2019-09-29 --prompt

Error

COLLAPSIBLE ERROR STACKTRACE

error[E0658]: yield syntax is experimental
 --> src/main.rs:2:13
  |
2 |     async { yield print!(":C") };
  |             ^^^^^^^^^^^^^^^^^^
  |
  = note: for more information, see https://github.com/rust-lang/rust/issues/43122
  = help: add `#![feature(generators)]` to the crate attributes to enable

error[E0727]: `async` generators are not yet supported
 --> src/main.rs:2:13
  |
2 |     async { yield print!(":C") };
  |             ^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at 'src/librustc/hir/map/hir_id_validator.rs:27: 
ItemLocalIds not assigned densely in ::main[0]. Max ItemLocalId = 14, missing IDs = ["[local_id: 1, node:unknown node (hir_id=HirId { owner: DefIndex(3), local_id: 1 })]"]; seens IDs = ["(HirId { owner: DefIndex(3), local_id: 0 } fn main (hir_id=HirId { owner: DefIndex(3), local_id: 0 }))", "(HirId { owner: DefIndex(3), local_id: 13 } block { ::std::future::from_generator(|| { (/*ERROR*/) }); } (hir_id=HirId { owner: DefIndex(3), local_id: 13 }))", "(HirId { owner: DefIndex(3), local_id: 10 } expr ::std::future::from_generator (hir_id=HirId { owner: DefIndex(3), local_id: 10 }))", "(HirId { owner: DefIndex(3), local_id: 7 } path segment std (hir_id=HirId { owner: DefIndex(3), local_id: 7 }))", "(HirId { owner: DefIndex(3), local_id: 4 } expr { (/*ERROR*/) } (hir_id=HirId { owner: DefIndex(3), local_id: 4 }))", "(HirId { owner: DefIndex(3), local_id: 14 } expr { ::std::future::from_generator(|| { (/*ERROR*/) }); } (hir_id=HirId { owner: DefIndex(3), local_id: 14 }))", "(HirId { owner: DefIndex(3), local_id: 11 } expr ::std::future::from_generator(|| { (/*ERROR*/) }) (hir_id=HirId { owner: DefIndex(3), local_id: 11 }))", "(HirId { owner: DefIndex(3), local_id: 8 } path segment future (hir_id=HirId { owner: DefIndex(3), local_id: 8 }))", "(HirId { owner: DefIndex(3), local_id: 5 } expr || { (/*ERROR*/) } (hir_id=HirId { owner: DefIndex(3), local_id: 5 }))", "(HirId { owner: DefIndex(3), local_id: 2 } expr (/*ERROR*/) (hir_id=HirId { owner: DefIndex(3), local_id: 2 }))", "(HirId { owner: DefIndex(3), local_id: 12 } stmt ::std::future::from_generator(|| { (/*ERROR*/) }); (hir_id=HirId { owner: DefIndex(3), local_id: 12 }))", "(HirId { owner: DefIndex(3), local_id: 9 } path segment from_generator (hir_id=HirId { owner: DefIndex(3), local_id: 9 }))", "(HirId { owner: DefIndex(3), local_id: 6 } path segment  (hir_id=HirId { owner: DefIndex(3), local_id: 6 }))", "(HirId { owner: DefIndex(3), local_id: 3 } block { (/*ERROR*/) } (hir_id=HirId { owner: DefIndex(3), local_id: 3 }))"]', src/librustc/util/bug.rs:37:26
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:77
   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:1052
   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: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:474
  12: std::panicking::begin_panic
  13: rustc::util::bug::opt_span_bug_fmt::{{closure}}
  14: rustc::ty::context::tls::with_opt::{{closure}}
  15: rustc::ty::context::tls::with_opt
  16: rustc::util::bug::opt_span_bug_fmt
  17: rustc::util::bug::bug_fmt
  18: rustc::hir::map::hir_id_validator::check_crate
  19: rustc_session::utils::<impl rustc_session::session::Session>::time
  20: rustc::hir::map::map_crate
  21: rustc_interface::passes::create_global_ctxt
  22: rustc_interface::queries::Queries::global_ctxt
  23: rustc_interface::interface::run_compiler_in_existing_thread_pool
  24: scoped_tls::ScopedKey<T>::set
  25: syntax::attr::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose 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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.43.0-nightly (58b834344 2020-02-05) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
end of query stack
error: aborting due to 2 previous errors

Some errors have detailed explanations: E0658, E0727.
For more information about an error, try `rustc --explain E0658`.

[nikomatsakis]

@chrissimpkins thanks for the bisection!

Annoyingly, it regressed in a rollup PR, which means there are many candidates:

• Docs: slice elements are equidistant #64703 (Docs: slice elements are equidistant) -- ❌
• Include message on tests that should panic but do not #64745 (Include message on tests that should panic but do not) -- ❌
• Remove stray references to the old global tcx #64781 (Remove stray references to the old global tcx) -- ❌
• Remove unused DepTrackingMap #64794 (Remove unused DepTrackingMap) -- ❌
• Account for tail expressions when pointing at return type #64802 (Account for tail expressions when pointing at return type) -- ❓
• hir: Disallow target_feature on constants #64809 (hir: Disallow target_feature on constants) -- ❌
• Fix div_duration() marked as stable by mistake #64815 (Fix div_duration() marked as stable by mistake) -- ❌
• update rtpSpawn's parameters type(It's prototype has been updated in libc) #64818 (update rtpSpawn's parameters type(It's prototype has been updated in libc)) -- ❌
• Thou shallt not .abort_if_errors() #64830 (Thou shallt not .abort_if_errors()) -- 🎯
• Stabilize map_get_key_value feature #64836 (Stabilize map_get_key_value feature) -- ❌
• pin.rs: fix links to primitives in documentation #64845 (pin.rs: fix links to primitives in documentation) -- ❌
• Upgrade env_logger to 0.7 #64847 (Upgrade env_logger to 0.7) -- ❌
• Add mailmap entry for Dustin Bensing by request #64851 (Add mailmap entry for Dustin Bensing by request) -- ❌
• check_match: improve diagnostics for let A = 2; with const A: i32 = 3 #64859 (check_match: improve diagnostics for let A = 2; with const A: i32 = 3) -- ❓

[nikomatsakis]

If I had to guess, I would guess #64830 (cc @estebank) triggered this regression, but #64859 or #64802 are possibilities. I would guess #64830 because it caused the compiler to keep compiling when it might've aborted, and maybe it would've aborted in these cases and hence never reached the code that causes an ICE.

If indeed I am correct, then this could be fixed by adding a delay_span_bug call at the point of the ICE (i.e., basically asserting that some error has occurred but otherwise just try to not crash).