ice: ` failed to compute implied bounds Coroutine(DefId`

[matthiaskrgr]

File: /tmp/im/45d62c73863a92cb3871aaaba9e7b5afe966a5a4.rs

auto-reduced (treereduce-rust):

#![feature(unboxed_closures)]
use std::future::Future;

async fn wrapper<F>(f: F)
where
    for<F> F:,
    for<'a> <i32 as FnOnce<(&'a mut i32,)>>::Output: Future<Output = ()> + 'a,
{
    let mut i = 41;
    &mut i;
}

original:

// edition:2018
// check-pass

#![feature(unboxed_closures)]
use std::future::Future;

async fn wrapper<F>(f: F)
where for<F> F: FnOnce<(&'a mut i32,)>,
    for<'a> <i32 as FnOnce<(&'a mut i32,)>>::Output: Future<Output=()> + 'a
{
    let mut i = 41;
    &mut i;
}

async fn add_one(i: &mut F) {
    *i = *i + 1;
}

fn main() {}

Version information

rustc 1.75.0-nightly (ab5c841a1 2023-10-25)
binary: rustc
commit-hash: ab5c841a1f3c09edc5ea07722519627c960aed17
commit-date: 2023-10-25
host: x86_64-unknown-linux-gnu
release: 1.75.0-nightly
LLVM version: 17.0.3

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

error[E0670]: `async fn` is not permitted in Rust 2015
 --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:4:1
  |
4 | async fn wrapper<F>(f: F)
  | ^^^^^ to use `async fn`, switch to Rust 2018 or later
  |
  = help: pass `--edition 2021` to `rustc`
  = note: for more on editions, read https://doc.rust-lang.org/edition-guide

error[E0658]: only lifetime parameters can be used in this context
 --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:6:9
  |
6 |     for<F> F:,
  |         ^
  |
  = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
  = help: add `#![feature(non_lifetime_binders)]` to the crate attributes to enable

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:11:2
   |
11 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs`

error[E0277]: expected a `FnOnce<(&'a mut i32,)>` closure, found `i32`
 --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:4:1
  |
4 | / async fn wrapper<F>(f: F)
5 | | where
6 | |     for<F> F:,
7 | |     for<'a> <i32 as FnOnce<(&'a mut i32,)>>::Output: Future<Output = ()> + 'a,
  | |______________________________________________________________________________^ expected an `FnOnce<(&'a mut i32,)>` closure, found `i32`
  |
  = help: the trait `for<'a> FnOnce<(&'a mut i32,)>` is not implemented for `i32`

error[E0277]: expected a `FnOnce<(&'a mut i32,)>` closure, found `i32`
 --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:4:10
  |
4 | async fn wrapper<F>(f: F)
  |          ^^^^^^^ expected an `FnOnce<(&'a mut i32,)>` closure, found `i32`
  |
  = help: the trait `for<'a> FnOnce<(&'a mut i32,)>` is not implemented for `i32`

error[E0277]: expected a `FnOnce<(&'a mut i32,)>` closure, found `i32`
  --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:8:1
   |
8  | / {
9  | |     let mut i = 41;
10 | |     &mut i;
11 | | }
   | |_^ expected an `FnOnce<(&'a mut i32,)>` closure, found `i32`
   |
   = help: the trait `for<'a> FnOnce<(&'a mut i32,)>` is not implemented for `i32`

warning: unused variable: `f`
 --> /tmp/icemaker_global_tempdir.OGfH7yzRDDs1/rustc_testrunner_tmpdir_reporting.GyfjgkDNkTIP/mvce.rs:4:21
  |
4 | async fn wrapper<F>(f: F)
  |                     ^ help: if this is intentional, prefix it with an underscore: `_f`
  |
  = note: `#[warn(unused_variables)]` on by default

error: internal compiler error: compiler/rustc_borrowck/src/type_check/free_region_relations.rs:321:33: failed to compute implied bounds Coroutine(DefId(0:8 ~ mvce[5878]::wrapper::{closure#0}), [F/#0, std::future::ResumeTy, (), (), CoroutineWitness(DefId(0:8 ~ mvce[5878]::wrapper::{closure#0}), [F/#0]), (F/#0,)], Static)

thread 'rustc' panicked at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/compiler/rustc_errors/src/lib.rs:1659:9:
Box<dyn Any>
stack backtrace:
   0:     0x7f77e536917c - std::backtrace_rs::backtrace::libunwind::trace::h866f402f2b7c0bba
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f77e536917c - std::backtrace_rs::backtrace::trace_unsynchronized::h49496fdc222c8507
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f77e536917c - std::sys_common::backtrace::_print_fmt::ha3bb87f7115465ff
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f77e536917c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h2df2d9ea73d83a54
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f77e53cb3e0 - core::fmt::rt::Argument::fmt::hafc42cfbf5ed0d04
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/core/src/fmt/rt.rs:142:9
   5:     0x7f77e53cb3e0 - core::fmt::write::hca2076664d4a5105
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/core/src/fmt/mod.rs:1117:17
   6:     0x7f77e535d00f - std::io::Write::write_fmt::h98796c32234a7fea
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/io/mod.rs:1762:15
   7:     0x7f77e5368f64 - std::sys_common::backtrace::_print::h2752a08f115c9ce3
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f77e5368f64 - std::sys_common::backtrace::print::hf0f5f9a9ad1e4b5f
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f77e536bbf7 - std::panicking::default_hook::{{closure}}::hfadb6461fe55452e
  10:     0x7f77e536b95f - std::panicking::default_hook::hea9d23f5d4088f4c
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/panicking.rs:292:9
  11:     0x7f77e7ed18e0 - std[667748eccaa7b38e]::panicking::update_hook::<alloc[ff2a8f107125114]::boxed::Box<rustc_driver_impl[9a9fc32bafb41e38]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f77e536c338 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hdda1ca31f157a447
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/alloc/src/boxed.rs:2021:9
  13:     0x7f77e536c338 - std::panicking::rust_panic_with_hook::hd95bfee795a92c13
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/panicking.rs:735:13
  14:     0x7f77e82974e4 - std[667748eccaa7b38e]::panicking::begin_panic::<rustc_errors[853efc71507e763b]::ExplicitBug>::{closure#0}
  15:     0x7f77e8289916 - std[667748eccaa7b38e]::sys_common::backtrace::__rust_end_short_backtrace::<std[667748eccaa7b38e]::panicking::begin_panic<rustc_errors[853efc71507e763b]::ExplicitBug>::{closure#0}, !>
  16:     0x7f77e8279c96 - std[667748eccaa7b38e]::panicking::begin_panic::<rustc_errors[853efc71507e763b]::ExplicitBug>
  17:     0x7f77e82710c4 - <rustc_errors[853efc71507e763b]::HandlerInner>::bug::<alloc[ff2a8f107125114]::string::String>
  18:     0x7f77e8270e84 - <rustc_errors[853efc71507e763b]::Handler>::bug::<alloc[ff2a8f107125114]::string::String>
  19:     0x7f77e831097d - rustc_middle[b225c6f618f5ae33]::util::bug::opt_span_bug_fmt::<rustc_span[39946a06a66a7393]::span_encoding::Span>::{closure#0}
  20:     0x7f77e82f8c6a - rustc_middle[b225c6f618f5ae33]::ty::context::tls::with_opt::<rustc_middle[b225c6f618f5ae33]::util::bug::opt_span_bug_fmt<rustc_span[39946a06a66a7393]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x7f77e82f8b08 - rustc_middle[b225c6f618f5ae33]::ty::context::tls::with_context_opt::<rustc_middle[b225c6f618f5ae33]::ty::context::tls::with_opt<rustc_middle[b225c6f618f5ae33]::util::bug::opt_span_bug_fmt<rustc_span[39946a06a66a7393]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x7f77e63e8390 - rustc_middle[b225c6f618f5ae33]::util::bug::bug_fmt
  23:     0x7f77e9b5f142 - <rustc_borrowck[2ca7a04d39bdc360]::type_check::free_region_relations::UniversalRegionRelationsBuilder>::add_implied_bounds
  24:     0x7f77e996a87c - rustc_borrowck[2ca7a04d39bdc360]::type_check::type_check
  25:     0x7f77e68085e3 - rustc_borrowck[2ca7a04d39bdc360]::nll::compute_regions
  26:     0x7f77e9da33f0 - rustc_borrowck[2ca7a04d39bdc360]::do_mir_borrowck
  27:     0x7f77e9d934f9 - rustc_borrowck[2ca7a04d39bdc360]::mir_borrowck
  28:     0x7f77e9d93099 - rustc_query_impl[faf73ee31f8b0020]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[faf73ee31f8b0020]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>
  29:     0x7f77e91453ac - rustc_query_system[8b4f6d9fea7b3c3]::query::plumbing::try_execute_query::<rustc_query_impl[faf73ee31f8b0020]::DynamicConfig<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::VecCache<rustc_span[39946a06a66a7393]::def_id::LocalDefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[faf73ee31f8b0020]::plumbing::QueryCtxt, false>
  30:     0x7f77e9144fd0 - rustc_query_impl[faf73ee31f8b0020]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  31:     0x7f77e996645f - <rustc_borrowck[2ca7a04d39bdc360]::type_check::TypeChecker>::prove_closure_bounds
  32:     0x7f77e9d62a71 - <rustc_borrowck[2ca7a04d39bdc360]::type_check::TypeChecker>::typeck_mir
  33:     0x7f77e996b2e6 - rustc_borrowck[2ca7a04d39bdc360]::type_check::type_check
  34:     0x7f77e68085e3 - rustc_borrowck[2ca7a04d39bdc360]::nll::compute_regions
  35:     0x7f77e9da33f0 - rustc_borrowck[2ca7a04d39bdc360]::do_mir_borrowck
  36:     0x7f77e9d934f9 - rustc_borrowck[2ca7a04d39bdc360]::mir_borrowck
  37:     0x7f77e9d93099 - rustc_query_impl[faf73ee31f8b0020]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[faf73ee31f8b0020]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>
  38:     0x7f77e91453ac - rustc_query_system[8b4f6d9fea7b3c3]::query::plumbing::try_execute_query::<rustc_query_impl[faf73ee31f8b0020]::DynamicConfig<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::VecCache<rustc_span[39946a06a66a7393]::def_id::LocalDefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[faf73ee31f8b0020]::plumbing::QueryCtxt, false>
  39:     0x7f77e9144fd0 - rustc_query_impl[faf73ee31f8b0020]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  40:     0x7f77e9cc2f11 - rustc_hir_analysis[7763bf1ab586a91f]::collect::type_of::type_of_opaque
  41:     0x7f77e9cc2cdb - rustc_query_impl[faf73ee31f8b0020]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[faf73ee31f8b0020]::query_impl::type_of_opaque::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>
  42:     0x7f77e9079685 - rustc_query_system[8b4f6d9fea7b3c3]::query::plumbing::try_execute_query::<rustc_query_impl[faf73ee31f8b0020]::DynamicConfig<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::DefaultCache<rustc_span[39946a06a66a7393]::def_id::DefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[faf73ee31f8b0020]::plumbing::QueryCtxt, false>
  43:     0x7f77e9ef341e - rustc_query_impl[faf73ee31f8b0020]::query_impl::type_of_opaque::get_query_non_incr::__rust_end_short_backtrace
  44:     0x7f77e9119a77 - rustc_middle[b225c6f618f5ae33]::query::plumbing::query_get_at::<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::DefaultCache<rustc_span[39946a06a66a7393]::def_id::DefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>>
  45:     0x7f77e907c5cd - rustc_hir_analysis[7763bf1ab586a91f]::collect::type_of::type_of
  46:     0x7f77e907a2e9 - rustc_query_impl[faf73ee31f8b0020]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[faf73ee31f8b0020]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>
  47:     0x7f77e9079685 - rustc_query_system[8b4f6d9fea7b3c3]::query::plumbing::try_execute_query::<rustc_query_impl[faf73ee31f8b0020]::DynamicConfig<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::DefaultCache<rustc_span[39946a06a66a7393]::def_id::DefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[faf73ee31f8b0020]::plumbing::QueryCtxt, false>
  48:     0x7f77e90792ab - rustc_query_impl[faf73ee31f8b0020]::query_impl::type_of::get_query_non_incr::__rust_end_short_backtrace
  49:     0x7f77e9119a77 - rustc_middle[b225c6f618f5ae33]::query::plumbing::query_get_at::<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::DefaultCache<rustc_span[39946a06a66a7393]::def_id::DefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 8usize]>>>
  50:     0x7f77e9bbfb01 - rustc_hir_analysis[7763bf1ab586a91f]::check::check::check_mod_item_types
  51:     0x7f77e9bbe4cd - rustc_query_impl[faf73ee31f8b0020]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[faf73ee31f8b0020]::query_impl::check_mod_item_types::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 0usize]>>
  52:     0x7f77e98e6cb4 - rustc_query_system[8b4f6d9fea7b3c3]::query::plumbing::try_execute_query::<rustc_query_impl[faf73ee31f8b0020]::DynamicConfig<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::DefaultCache<rustc_span[39946a06a66a7393]::def_id::LocalModDefId, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[faf73ee31f8b0020]::plumbing::QueryCtxt, false>
  53:     0x7f77e98e6643 - rustc_query_impl[faf73ee31f8b0020]::query_impl::check_mod_item_types::get_query_non_incr::__rust_end_short_backtrace
  54:     0x7f77e944bdb2 - rustc_hir_analysis[7763bf1ab586a91f]::check_crate
  55:     0x7f77e9a35756 - rustc_interface[e333ecdbf287bc9f]::passes::analysis
  56:     0x7f77e9a35175 - rustc_query_impl[faf73ee31f8b0020]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[faf73ee31f8b0020]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 1usize]>>
  57:     0x7f77e9afbee6 - rustc_query_system[8b4f6d9fea7b3c3]::query::plumbing::try_execute_query::<rustc_query_impl[faf73ee31f8b0020]::DynamicConfig<rustc_query_system[8b4f6d9fea7b3c3]::query::caches::SingleCache<rustc_middle[b225c6f618f5ae33]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[faf73ee31f8b0020]::plumbing::QueryCtxt, false>
  58:     0x7f77e9afbd15 - rustc_query_impl[faf73ee31f8b0020]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  59:     0x7f77e9d4248d - std[667748eccaa7b38e]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[e333ecdbf287bc9f]::util::run_in_thread_with_globals<rustc_interface[e333ecdbf287bc9f]::interface::run_compiler<core[f43f289626e60610]::result::Result<(), rustc_span[39946a06a66a7393]::ErrorGuaranteed>, rustc_driver_impl[9a9fc32bafb41e38]::run_compiler::{closure#1}>::{closure#0}, core[f43f289626e60610]::result::Result<(), rustc_span[39946a06a66a7393]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f43f289626e60610]::result::Result<(), rustc_span[39946a06a66a7393]::ErrorGuaranteed>>
  60:     0x7f77e9d41773 - <<std[667748eccaa7b38e]::thread::Builder>::spawn_unchecked_<rustc_interface[e333ecdbf287bc9f]::util::run_in_thread_with_globals<rustc_interface[e333ecdbf287bc9f]::interface::run_compiler<core[f43f289626e60610]::result::Result<(), rustc_span[39946a06a66a7393]::ErrorGuaranteed>, rustc_driver_impl[9a9fc32bafb41e38]::run_compiler::{closure#1}>::{closure#0}, core[f43f289626e60610]::result::Result<(), rustc_span[39946a06a66a7393]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f43f289626e60610]::result::Result<(), rustc_span[39946a06a66a7393]::ErrorGuaranteed>>::{closure#1} as core[f43f289626e60610]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  61:     0x7f77e5377105 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3d899b39694f6cd5
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/alloc/src/boxed.rs:2007:9
  62:     0x7f77e5377105 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hdaaee2e740e70fd9
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/alloc/src/boxed.rs:2007:9
  63:     0x7f77e5377105 - std::sys::unix::thread::Thread::new::thread_start::h5d67d25c88de79b5
                               at /rustc/ab5c841a1f3c09edc5ea07722519627c960aed17/library/std/src/sys/unix/thread.rs:108:17
  64:     0x7f77e51409eb - <unknown>
  65:     0x7f77e51c47cc - <unknown>
  66:                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 1.75.0-nightly (ab5c841a1 2023-10-25) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [mir_borrowck] borrow-checking `wrapper::{closure#0}`
#1 [mir_borrowck] borrow-checking `wrapper`
#2 [type_of_opaque] computing type of opaque `wrapper::{opaque#0}`
#3 [type_of] computing type of `wrapper::{opaque#0}`
#4 [check_mod_item_types] checking item types in top-level module
#5 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 7 previous errors; 1 warning emitted

Some errors have detailed explanations: E0277, E0601, E0658, E0670.
For more information about an error, try `rustc --explain E0277`.

[matthiaskrgr]

Regression in ab5c841
#117159 cc @oli-obk 😅

[oli-obk]

I knew this was a source of ICEs 😃

Most of these should already be reachable if they are in the body of a constant used in an array length. If you want to try fuzzing by sticking code into a const body...