ICE: cfi: `encode_ty: unexpected 'CoroutineWitness'`

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(async_closure)]

fn main() {
    let a = async move |a: i32, b: i32| {};
    let b = |a: i32, b: i32| {};
    a(1, 2);
    b(1, 2);
}

original code

original:

//@ compile-flags: --cfg something
//@ edition:2018

#![feature(async_closure)]
#![deny(unused_variables)]

async fn foo_async(
    a: i32,
    //~^ ERROR unused variable: `a`
    #[allow(unused_variables)] b: i32,
) {}
fn foo(
    #[allow(unused_variables)] a: i32,
    b: i32,
    //~^ ERROR unused variable: `b`
) {}

struct RefStruct {}
impl RefStruct {
    async fn bar_async(
        &self,
        a: i32,
        //~^ ERROR unused variable: `a`
        #[allow(unused_variables)] b: i32,
    ) {}
    fn bar(
        &self,
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    ) {}
    fn issue_64682_associated_fn(
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    ) {}
}
trait RefTrait {
    fn bar(
        &self,
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    ) {}
    fn issue_64682_associated_fn(
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    ) {}
}
impl RefTrait for RefStruct {
    fn bar(
        &self,
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    ) {}
    fn issue_64682_associated_fn(
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    ) {}
}

fn main() {
    let _: fn(_, _) = foo;
    let a = async move |
        a: i32,
        //~^ ERROR unused variable: `a`
        #[allow(unused_variables)] b: i32,
    | {};
    let b = |
        #[allow(unused_variables)] a: i32,
        b: i32,
        //~^ ERROR unused variable: `b`
    | {};
    a(1, 2);
    b(1, 2);
}

Version information

rustc 1.79.0-nightly (3cdcdaf31 2024-03-18)
binary: rustc
commit-hash: 3cdcdaf31b45f8045164aae9604573d23091970b
commit-date: 2024-03-18
host: x86_64-unknown-linux-gnu
release: 1.79.0-nightly
LLVM version: 18.1.2

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --edition=2021 --cap-lints=warn -Zsanitizer=cfi -Ccodegen-units=1 -Clto

Program output

warning: unused variable: `a`
 --> /tmp/icemaker_global_tempdir.Zzjtx1Evw50c/rustc_testrunner_tmpdir_reporting.EkN8stMQHPaP/mvce.rs:4:25
  |
4 |     let a = async move |a: i32, b: i32| {};
  |                         ^ help: if this is intentional, prefix it with an underscore: `_a`
  |
  = note: `#[warn(unused_variables)]` on by default

warning: unused variable: `b`
 --> /tmp/icemaker_global_tempdir.Zzjtx1Evw50c/rustc_testrunner_tmpdir_reporting.EkN8stMQHPaP/mvce.rs:4:33
  |
4 |     let a = async move |a: i32, b: i32| {};
  |                                 ^ help: if this is intentional, prefix it with an underscore: `_b`

warning: unused variable: `a`
 --> /tmp/icemaker_global_tempdir.Zzjtx1Evw50c/rustc_testrunner_tmpdir_reporting.EkN8stMQHPaP/mvce.rs:5:14
  |
5 |     let b = |a: i32, b: i32| {};
  |              ^ help: if this is intentional, prefix it with an underscore: `_a`

warning: unused variable: `b`
 --> /tmp/icemaker_global_tempdir.Zzjtx1Evw50c/rustc_testrunner_tmpdir_reporting.EkN8stMQHPaP/mvce.rs:5:22
  |
5 |     let b = |a: i32, b: i32| {};
  |                      ^ help: if this is intentional, prefix it with an underscore: `_b`

warning: unused implementer of `Future` that must be used
 --> /tmp/icemaker_global_tempdir.Zzjtx1Evw50c/rustc_testrunner_tmpdir_reporting.EkN8stMQHPaP/mvce.rs:6:5
  |
6 |     a(1, 2);
  |     ^^^^^^^
  |
  = note: futures do nothing unless you `.await` or poll them
  = note: `#[warn(unused_must_use)]` on by default

error: internal compiler error: compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs:737:13: encode_ty: unexpected `CoroutineWitness(DefId(0:5 ~ mvce[abe4]::main::{closure#0}::{closure#0}), [])`

thread 'rustc' panicked at compiler/rustc_middle/src/util/bug.rs:35:44:
Box<dyn Any>
stack backtrace:
   0:     0x7fc2e75a1fa5 - std::backtrace_rs::backtrace::libunwind::trace::h14c26439c9e659cb
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x7fc2e75a1fa5 - std::backtrace_rs::backtrace::trace_unsynchronized::h44d92edd05bbbfda
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fc2e75a1fa5 - std::sys_common::backtrace::_print_fmt::h13f1beea5570cb83
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7fc2e75a1fa5 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hb8ca44e969e3f71b
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fc2e75f2feb - core::fmt::rt::Argument::fmt::h5c946a89981df55e
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/core/src/fmt/rt.rs:142:9
   5:     0x7fc2e75f2feb - core::fmt::write::hd586e7360777cc96
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/core/src/fmt/mod.rs:1153:17
   6:     0x7fc2e7596cbf - std::io::Write::write_fmt::h710cbd7bbf99ccca
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/io/mod.rs:1843:15
   7:     0x7fc2e75a1d7e - std::sys_common::backtrace::_print::hf1afff5c335e465f
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7fc2e75a1d7e - std::sys_common::backtrace::print::he54a51a147efc885
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7fc2e75a49f9 - std::panicking::default_hook::{{closure}}::hcd08c4e3ffa464ca
  10:     0x7fc2e75a4763 - std::panicking::default_hook::h2663042b363aa298
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/panicking.rs:292:9
  11:     0x7fc2e41ba58f - std[f1ab4ce7166604a0]::panicking::update_hook::<alloc[ef09d9835563b69e]::boxed::Box<rustc_driver_impl[76e846938966200a]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7fc2e75a5150 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hcd6186c20f61b1dd
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/alloc/src/boxed.rs:2034:9
  13:     0x7fc2e75a5150 - std::panicking::rust_panic_with_hook::h2a6da5de52d72055
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/panicking.rs:783:13
  14:     0x7fc2e41e6a54 - std[f1ab4ce7166604a0]::panicking::begin_panic::<rustc_errors[c906f5c4cf1f88ae]::ExplicitBug>::{closure#0}
  15:     0x7fc2e41e3976 - std[f1ab4ce7166604a0]::sys_common::backtrace::__rust_end_short_backtrace::<std[f1ab4ce7166604a0]::panicking::begin_panic<rustc_errors[c906f5c4cf1f88ae]::ExplicitBug>::{closure#0}, !>
  16:     0x7fc2e41e3656 - std[f1ab4ce7166604a0]::panicking::begin_panic::<rustc_errors[c906f5c4cf1f88ae]::ExplicitBug>
  17:     0x7fc2e41efed1 - <rustc_errors[c906f5c4cf1f88ae]::diagnostic::BugAbort as rustc_errors[c906f5c4cf1f88ae]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x7fc2e4675b91 - rustc_middle[712e48954d6afe8b]::util::bug::opt_span_bug_fmt::<rustc_span[74819862fbf5924e]::span_encoding::Span>::{closure#0}
  19:     0x7fc2e4658ffa - rustc_middle[712e48954d6afe8b]::ty::context::tls::with_opt::<rustc_middle[712e48954d6afe8b]::util::bug::opt_span_bug_fmt<rustc_span[74819862fbf5924e]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7fc2e4658e98 - rustc_middle[712e48954d6afe8b]::ty::context::tls::with_context_opt::<rustc_middle[712e48954d6afe8b]::ty::context::tls::with_opt<rustc_middle[712e48954d6afe8b]::util::bug::opt_span_bug_fmt<rustc_span[74819862fbf5924e]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7fc2e239c5a0 - rustc_middle[712e48954d6afe8b]::util::bug::bug_fmt
  22:     0x7fc2e4b28802 - rustc_symbol_mangling[6a6f4f831c70879f]::typeid::typeid_itanium_cxx_abi::encode_ty
  23:     0x7fc2e4b260b7 - rustc_symbol_mangling[6a6f4f831c70879f]::typeid::typeid_itanium_cxx_abi::encode_args
  24:     0x7fc2e4b26a8f - rustc_symbol_mangling[6a6f4f831c70879f]::typeid::typeid_itanium_cxx_abi::encode_ty
  25:     0x7fc2e4b27252 - rustc_symbol_mangling[6a6f4f831c70879f]::typeid::typeid_itanium_cxx_abi::encode_ty
  26:     0x7fc2e4b2b5f2 - rustc_symbol_mangling[6a6f4f831c70879f]::typeid::typeid_itanium_cxx_abi::typeid_for_fnabi
  27:     0x7fc2e4b2a557 - rustc_symbol_mangling[6a6f4f831c70879f]::typeid::typeid_itanium_cxx_abi::typeid_for_instance
  28:     0x7fc2e29d368a - <rustc_codegen_llvm[4330239e0645e5fe]::context::CodegenCx as rustc_codegen_ssa[c5bbf89d97e47a4c]::traits::declare::PreDefineMethods>::predefine_fn
  29:     0x7fc2e6128613 - rustc_codegen_llvm[4330239e0645e5fe]::base::compile_codegen_unit::module_codegen
  30:     0x7fc2e6124956 - <rustc_codegen_llvm[4330239e0645e5fe]::LlvmCodegenBackend as rustc_codegen_ssa[c5bbf89d97e47a4c]::traits::backend::ExtraBackendMethods>::compile_codegen_unit
  31:     0x7fc2e631aceb - rustc_codegen_ssa[c5bbf89d97e47a4c]::base::codegen_crate::<rustc_codegen_llvm[4330239e0645e5fe]::LlvmCodegenBackend>
  32:     0x7fc2e630daa9 - <rustc_codegen_llvm[4330239e0645e5fe]::LlvmCodegenBackend as rustc_codegen_ssa[c5bbf89d97e47a4c]::traits::backend::CodegenBackend>::codegen_crate
  33:     0x7fc2e630d41f - rustc_interface[6e8cd5a4c59e5ecd]::passes::start_codegen
  34:     0x7fc2e630cbbf - <rustc_interface[6e8cd5a4c59e5ecd]::queries::Queries>::codegen_and_build_linker
  35:     0x7fc2e60900d7 - rustc_interface[6e8cd5a4c59e5ecd]::interface::run_compiler::<core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>, rustc_driver_impl[76e846938966200a]::run_compiler::{closure#0}>::{closure#0}
  36:     0x7fc2e6160a45 - std[f1ab4ce7166604a0]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[6e8cd5a4c59e5ecd]::util::run_in_thread_with_globals<rustc_interface[6e8cd5a4c59e5ecd]::util::run_in_thread_pool_with_globals<rustc_interface[6e8cd5a4c59e5ecd]::interface::run_compiler<core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>, rustc_driver_impl[76e846938966200a]::run_compiler::{closure#0}>::{closure#0}, core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>>::{closure#0}, core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>>
  37:     0x7fc2e6160872 - <<std[f1ab4ce7166604a0]::thread::Builder>::spawn_unchecked_<rustc_interface[6e8cd5a4c59e5ecd]::util::run_in_thread_with_globals<rustc_interface[6e8cd5a4c59e5ecd]::util::run_in_thread_pool_with_globals<rustc_interface[6e8cd5a4c59e5ecd]::interface::run_compiler<core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>, rustc_driver_impl[76e846938966200a]::run_compiler::{closure#0}>::{closure#0}, core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>>::{closure#0}, core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[254dfe32d5b92b13]::result::Result<(), rustc_span[74819862fbf5924e]::ErrorGuaranteed>>::{closure#1} as core[254dfe32d5b92b13]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  38:     0x7fc2e75ae919 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h24cb68345bc0eeeb
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/alloc/src/boxed.rs:2020:9
  39:     0x7fc2e75ae919 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h1d32c6c52d61212f
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/alloc/src/boxed.rs:2020:9
  40:     0x7fc2e75ae919 - std::sys::pal::unix::thread::Thread::new::thread_start::h789f3c93e78a3e64
                               at /rustc/3cdcdaf31b45f8045164aae9604573d23091970b/library/std/src/sys/pal/unix/thread.rs:108:17
  41:     0x7fc2e10a955a - <unknown>
  42:     0x7fc2e1126a3c - <unknown>
  43:                0x0 - <unknown>

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 1.79.0-nightly (3cdcdaf31 2024-03-18) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z sanitizer=cfi -C codegen-units=1 -C lto -Z dump-mir-dir=dir

query stack during panic:
end of query stack
error: aborting due to 1 previous error; 5 warnings emitted

[workingjubilee]

cc @rcvalle @maurer

[maurer]

(Previously incorrectly thought this compiled with my patch; there were still issues.)

[workingjubilee]

oh does it now? interesting.

[compiler-errors]

@maurer: This doesn't change the way that TyKind::CoroutineClosure (i.e. async closures) are encoded in CFI, so this isn't a fix. This still ICEs, for example:

#![feature(async_closure)]

#[inline(never)]
fn foo<T>(x: T) {}

fn main() {
    let a = async move |a: i32, b: i32| {};
    foo(a);
}

Not sure why we're not just encoding the parent args for closures and coroutine-closures. I'll put up a PR.

@rustbot claim

[maurer]

Yes, you're right, we need to be able to encode these.

[compiler-errors]

Well @rcvalle just pinged me and said he may have a PR that already addresses this, so I guess I'll wait for him to comment. If not, I'll put up a fix for this in a few days since I'm the expert on ty::CoroutineClosure.