ice: expected async fn to have impl Future output, but it returns impl Future<Output = i32>

[matthiaskrgr]

Code

#![feature(async_fn_in_trait)]
#![allow(incomplete_features)]

trait MyTrait {
    async fn foo(&self) -> i32;
    async fn bar(&self) -> i32;
}

impl MyTrait for i32 {
    async fn MyTrait(&self) -> i32 {
        *self
    }

    async fn bar(&self) -> i32 {
        self.foo().await
    }
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.72.0-nightly (6fc0273b5 2023-06-20)
binary: rustc
commit-hash: 6fc0273b5a57eb78cc00841181113fda3e509478
commit-date: 2023-06-20
host: x86_64-unknown-linux-gnu
release: 1.72.0-nightly
LLVM version: 16.0.5

Error output

error[E0407]: method `MyTrait` is not a member of trait `MyTrait`
  --> crash.rs:10:5
   |
10 | /     async fn MyTrait(&self) -> i32 {
11 | |         *self
12 | |     }
   | |_____^ not a member of trait `MyTrait`

Backtrace

error: internal compiler error: compiler/rustc_hir_analysis/src/check/mod.rs:416:21: expected async fn to have `impl Future` output, but it returns impl Future<Output = i32>
 --> crash.rs:5:14
  |
5 |     async fn foo(&self) -> i32;
  |              ^^^

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/compiler/rustc_errors/src/lib.rs:994:33
stack backtrace:
   0:     0x7f7f51390dc1 - std::backtrace_rs::backtrace::libunwind::trace::h1549ddfd8a258aeb
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f7f51390dc1 - std::backtrace_rs::backtrace::trace_unsynchronized::he8406d242e2495d8
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f7f51390dc1 - std::sys_common::backtrace::_print_fmt::hcbd55f29c8b6bb87
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f7f51390dc1 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hc330ee62a3534284
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f7f513f23df - core::fmt::rt::Argument::fmt::h944c617571c59f55
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/core/src/fmt/rt.rs:138:9
   5:     0x7f7f513f23df - core::fmt::write::hdfb34466040e87e7
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/core/src/fmt/mod.rs:1094:21
   6:     0x7f7f51383927 - std::io::Write::write_fmt::hc3f6c030108d0f8f
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/io/mod.rs:1714:15
   7:     0x7f7f51390bd5 - std::sys_common::backtrace::_print::h090226f042b44130
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f7f51390bd5 - std::sys_common::backtrace::print::h881d7f1cf79f05ba
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f7f51393983 - std::panicking::default_hook::{{closure}}::hf0985bb10495a514
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/panicking.rs:269:22
  10:     0x7f7f51393714 - std::panicking::default_hook::h1534132078381b49
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/panicking.rs:288:9
  11:     0x7f7f501af98b - <rustc_driver_impl[6aaee82d15fcd1b5]::install_ice_hook::{closure#0} as core[c45177fb2e5c300e]::ops::function::FnOnce<(&core[c45177fb2e5c300e]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  12:     0x7f7f513941ae - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h461508deb496d74f
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/alloc/src/boxed.rs:2007:9
  13:     0x7f7f513941ae - std::panicking::rust_panic_with_hook::h1bba696c0525b1be
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/panicking.rs:709:13
  14:     0x7f7f503120f1 - std[33c81befc1327b2c]::panicking::begin_panic::<rustc_errors[45ab742dbf8d46a1]::ExplicitBug>::{closure#0}
  15:     0x7f7f5030fa16 - std[33c81befc1327b2c]::sys_common::backtrace::__rust_end_short_backtrace::<std[33c81befc1327b2c]::panicking::begin_panic<rustc_errors[45ab742dbf8d46a1]::ExplicitBug>::{closure#0}, !>
  16:     0x7f7f502b9c46 - std[33c81befc1327b2c]::panicking::begin_panic::<rustc_errors[45ab742dbf8d46a1]::ExplicitBug>
  17:     0x7f7f5030e20e - <rustc_errors[45ab742dbf8d46a1]::HandlerInner>::span_bug::<rustc_span[a992d7e7973c1be2]::span_encoding::Span, alloc[5f60cdf87399dbe2]::string::String>
  18:     0x7f7f5030df3d - <rustc_errors[45ab742dbf8d46a1]::Handler>::span_bug::<rustc_span[a992d7e7973c1be2]::span_encoding::Span, alloc[5f60cdf87399dbe2]::string::String>
  19:     0x7f7f5031234d - rustc_middle[4875513d3ec05678]::util::bug::opt_span_bug_fmt::<rustc_span[a992d7e7973c1be2]::span_encoding::Span>::{closure#0}
  20:     0x7f7f5031237a - rustc_middle[4875513d3ec05678]::ty::context::tls::with_opt::<rustc_middle[4875513d3ec05678]::util::bug::opt_span_bug_fmt<rustc_span[a992d7e7973c1be2]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x7f7f5031109a - rustc_middle[4875513d3ec05678]::ty::context::tls::with_context_opt::<rustc_middle[4875513d3ec05678]::ty::context::tls::with_opt<rustc_middle[4875513d3ec05678]::util::bug::opt_span_bug_fmt<rustc_span[a992d7e7973c1be2]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x7f7f50310a64 - rustc_middle[4875513d3ec05678]::util::bug::span_bug_fmt::<rustc_span[a992d7e7973c1be2]::span_encoding::Span>
  23:     0x7f7f4f4b0535 - rustc_hir_analysis[37adeb9a3b5fd3e]::check::check::check_impl_items_against_trait
  24:     0x7f7f4f4a40ee - rustc_hir_analysis[37adeb9a3b5fd3e]::check::check::check_mod_item_types
  25:     0x7f7f4ee4ca3c - rustc_query_impl[8b1986df9d148b15]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8b1986df9d148b15]::query_impl::check_mod_item_types::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4875513d3ec05678]::query::erase::Erased<[u8; 0usize]>>
  26:     0x7f7f4ee4ca1e - <rustc_query_impl[8b1986df9d148b15]::query_impl::check_mod_item_types::dynamic_query::{closure#2} as core[c45177fb2e5c300e]::ops::function::FnOnce<(rustc_middle[4875513d3ec05678]::ty::context::TyCtxt, rustc_span[a992d7e7973c1be2]::def_id::LocalDefId)>>::call_once
  27:     0x7f7f4e857f6f - rustc_query_system[cca36986bbe76e10]::query::plumbing::try_execute_query::<rustc_query_impl[8b1986df9d148b15]::DynamicConfig<rustc_query_system[cca36986bbe76e10]::query::caches::VecCache<rustc_span[a992d7e7973c1be2]::def_id::LocalDefId, rustc_middle[4875513d3ec05678]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[8b1986df9d148b15]::plumbing::QueryCtxt, false>
  28:     0x7f7f4fb1bc12 - rustc_query_impl[8b1986df9d148b15]::query_impl::check_mod_item_types::get_query_non_incr::__rust_end_short_backtrace
  29:     0x7f7f4f5c1927 - <rustc_middle[4875513d3ec05678]::hir::map::Map>::for_each_module::<rustc_hir_analysis[37adeb9a3b5fd3e]::check_crate::{closure#6}::{closure#0}>
  30:     0x7f7f4f5c113d - <rustc_session[9b1eb2cc4d9315ee]::session::Session>::time::<(), rustc_hir_analysis[37adeb9a3b5fd3e]::check_crate::{closure#6}>
  31:     0x7f7f4f5bf657 - rustc_hir_analysis[37adeb9a3b5fd3e]::check_crate
  32:     0x7f7f4f5b2cfa - rustc_interface[f2bb2657274807ca]::passes::analysis
  33:     0x7f7f4f61ba7a - rustc_query_impl[8b1986df9d148b15]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[8b1986df9d148b15]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[4875513d3ec05678]::query::erase::Erased<[u8; 1usize]>>
  34:     0x7f7f4f61ba69 - <rustc_query_impl[8b1986df9d148b15]::query_impl::analysis::dynamic_query::{closure#2} as core[c45177fb2e5c300e]::ops::function::FnOnce<(rustc_middle[4875513d3ec05678]::ty::context::TyCtxt, ())>>::call_once
  35:     0x7f7f4f8313e8 - rustc_query_system[cca36986bbe76e10]::query::plumbing::try_execute_query::<rustc_query_impl[8b1986df9d148b15]::DynamicConfig<rustc_query_system[cca36986bbe76e10]::query::caches::SingleCache<rustc_middle[4875513d3ec05678]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[8b1986df9d148b15]::plumbing::QueryCtxt, false>
  36:     0x7f7f4f8311c7 - rustc_query_impl[8b1986df9d148b15]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  37:     0x7f7f4f6cc4d5 - <rustc_middle[4875513d3ec05678]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[6aaee82d15fcd1b5]::run_compiler::{closure#1}::{closure#2}::{closure#4}, core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>>
  38:     0x7f7f4f6cb49e - rustc_span[a992d7e7973c1be2]::set_source_map::<core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>, rustc_interface[f2bb2657274807ca]::interface::run_compiler<core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>, rustc_driver_impl[6aaee82d15fcd1b5]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  39:     0x7f7f4f6c3c79 - <scoped_tls[708333a90650a86b]::ScopedKey<rustc_span[a992d7e7973c1be2]::SessionGlobals>>::set::<rustc_interface[f2bb2657274807ca]::interface::run_compiler<core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>, rustc_driver_impl[6aaee82d15fcd1b5]::run_compiler::{closure#1}>::{closure#0}, core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>>
  40:     0x7f7f4f6c3276 - std[33c81befc1327b2c]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[f2bb2657274807ca]::util::run_in_thread_pool_with_globals<rustc_interface[f2bb2657274807ca]::interface::run_compiler<core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>, rustc_driver_impl[6aaee82d15fcd1b5]::run_compiler::{closure#1}>::{closure#0}, core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>>
  41:     0x7f7f4f6c3025 - <<std[33c81befc1327b2c]::thread::Builder>::spawn_unchecked_<rustc_interface[f2bb2657274807ca]::util::run_in_thread_pool_with_globals<rustc_interface[f2bb2657274807ca]::interface::run_compiler<core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>, rustc_driver_impl[6aaee82d15fcd1b5]::run_compiler::{closure#1}>::{closure#0}, core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[c45177fb2e5c300e]::result::Result<(), rustc_span[a992d7e7973c1be2]::ErrorGuaranteed>>::{closure#1} as core[c45177fb2e5c300e]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  42:     0x7f7f5139e635 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h9b20d6135dc15bb0
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/alloc/src/boxed.rs:1993:9
  43:     0x7f7f5139e635 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he0b0b7512c2c83c3
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/alloc/src/boxed.rs:1993:9
  44:     0x7f7f5139e635 - std::sys::unix::thread::Thread::new::thread_start::hf6254ce8e731db9d
                               at /rustc/6fc0273b5a57eb78cc00841181113fda3e509478/library/std/src/sys/unix/thread.rs:108:17
  45:     0x7f7f4ce9d44b - <unknown>
  46:     0x7f7f4cf20e40 - <unknown>
  47:                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 1.72.0-nightly (6fc0273b5 2023-06-20) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [check_mod_item_types] checking item types in top-level module
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors

[matthiaskrgr]

#112596 cc @compiler-errors