Make {Mutex, Notify, OnceCell, RwLock, Semaphore}::const_new always available

[NobodyXu]

Motivation

MSRV is bumped to 1.63 in #5887 , nowMutex::new is usable in const context, so these functions should now be always available.

Solution

This patch makes these function always available.

Also use assert! in const function to ensure correctness instead of silently truncating the value and remove use of cfg tokio_no_const_mutex_new.

This PR might resolve #4623

[NobodyXu]

Why not make Mutex::new and others const on rust-version >= 1.63?

Unfortunately they can't since with cfg(all(tokio_unstable, feature = "tracing")) Mutex::new will log using tracing::trace! and it also constructs a span using tracing::trace_span!.

From #4623 (comment)

[NobodyXu]

I see #5877 tries to bump msrv to 1.63 and it will eliminate the use of build.rs and make const_new always available.
If that is desired, I can close this PR and open another one to bump msrv and removes build.rs.

Or merging this PR first then talk about bumping msrv later, I'm fine with either.

[taiki-e]

Personally, I would prefer to raise the MSRV, but we will have to hear from other maintainers on that.

[carllerche]

We can raise the MSRV to 1.63 and remove the trace call from Mutex::new (tracing is unstable).

[NobodyXu]

Somehow rebasing this against main caused CI to fail:

thread 'tokio-runtime-worker' panicked at 'explicit panic', tokio/src/runtime/scheduler/multi_thread_alt/queue.rs:149:13
stack backtrace:
   0: rust_begin_unwind
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/std/src/panicking.rs:593:5
   1: core::panicking::panic_fmt
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/core/src/panicking.rs:67:14
   2: core::panicking::panic
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/core/src/panicking.rs:117:5
   3: tokio::runtime::scheduler::multi_thread_alt::queue::Local<T>::push_back
             at ./src/runtime/scheduler/multi_thread_alt/queue.rs:149:13
   4: tokio::runtime::scheduler::multi_thread_alt::worker::Worker::next_remote_task_batch_synced
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:799:9
   5: tokio::runtime::scheduler::multi_thread_alt::worker::Worker::do_park
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:1154:29
   6: tokio::runtime::scheduler::multi_thread_alt::worker::Worker::park
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:1125:30
   7: tokio::runtime::scheduler::multi_thread_alt::worker::Worker::next_task
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:707:46
   8: tokio::runtime::scheduler::multi_thread_alt::worker::Worker::run
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:570:35
   9: tokio::runtime::scheduler::multi_thread_alt::worker::run::{{closure}}::{{closure}}
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:502:23
  10: tokio::runtime::context::scoped::Scoped<T>::set
             at ./src/runtime/context/scoped.rs:40:9
  11: tokio::runtime::context::set_scheduler::{{closure}}
             at ./src/runtime/context.rs:176:26
  12: std::thread::local::LocalKey<T>::try_with
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/std/src/thread/local.rs:270:16
  13: std::thread::local::LocalKey<T>::with
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/std/src/thread/local.rs:246:9
  14: tokio::runtime::context::set_scheduler
             at ./src/runtime/context.rs:176:9
  15: tokio::runtime::scheduler::multi_thread_alt::worker::run::{{closure}}
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:498:9
  16: tokio::runtime::context::runtime::enter_runtime
             at ./src/runtime/context/runtime.rs:65:16
  17: tokio::runtime::scheduler::multi_thread_alt::worker::run
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:487:5
  18: tokio::runtime::scheduler::multi_thread_alt::worker::create::{{closure}}
             at ./src/runtime/scheduler/multi_thread_alt/worker.rs:334:49
  19: <tokio::runtime::blocking::task::BlockingTask<T> as core::future::future::Future>::poll
             at ./src/runtime/blocking/task.rs:42:21
  20: <tracing::instrument::Instrumented<T> as core::future::future::Future>::poll
             at /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tracing-0.1.37/src/instrument.rs:272:9
  21: tokio::runtime::task::core::Core<T,S>::poll::{{closure}}
             at ./src/runtime/task/core.rs:334:17
  22: tokio::loom::std::unsafe_cell::UnsafeCell<T>::with_mut
             at ./src/loom/std/unsafe_cell.rs:16:9
  23: tokio::runtime::task::core::Core<T,S>::poll
             at ./src/runtime/task/core.rs:323:13
  24: tokio::runtime::task::harness::poll_future::{{closure}}
             at ./src/runtime/task/harness.rs:485:19
  25: <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/core/src/panic/unwind_safe.rs:271:9
  26: std::panicking::try::do_call
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/std/src/panicking.rs:500:40
  27: __rust_try
  28: std::panicking::try
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/std/src/panicking.rs:464:19
  29: std::panic::catch_unwind
             at /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/library/std/src/panic.rs:142:14
  30: tokio::runtime::task::harness::poll_future
             at ./src/runtime/task/harness.rs:473:18
  31: tokio::runtime::task::harness::Harness<T,S>::poll_inner
             at ./src/runtime/task/harness.rs:208:27
  32: tokio::runtime::task::harness::Harness<T,S>::poll
             at ./src/runtime/task/harness.rs:153:15
  33: tokio::runtime::task::raw::poll
             at ./src/runtime/task/raw.rs:276:5
  34: tokio::runtime::task::raw::RawTask::poll
             at ./src/runtime/task/raw.rs:200:18
  35: tokio::runtime::task::UnownedTask<S>::run
             at ./src/runtime/task/mod.rs:437:9
  36: tokio::runtime::blocking::pool::Task::run
             at ./src/runtime/blocking/pool.rs:159:9
  37: tokio::runtime::blocking::pool::Inner::run
             at ./src/runtime/blocking/pool.rs:513:17
  38: tokio::runtime::blocking::pool::Spawner::spawn_thread::{{closure}}
             at ./src/runtime/blocking/pool.rs:471:13
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
worker thread panicking; aborting process

I don't think this is caused by this PR.

[Darksonn]

If we are raising the MSRV, then it should happen in its own separate PR.

[NobodyXu]

If we are raising the MSRV, then it should happen in its own separate PR.

I've opened #5887 to bump tokio MSRV to 1.63

[Darksonn]

There are some tests using this that currently only run when the parking_lot feature is set. Please make them run always.

[NobodyXu]

There are some tests using this that currently only run when the parking_lot feature is set. Please make them run always.

Thanks, I've enabled these tests by default and also remove use of cfg tokio_no_const_mutex_new.

[NobodyXu]

We can raise the MSRV to 1.63 and remove the trace call from Mutex::new (tracing is unstable).

I think it's better to do this in a separate PR and it will require quite some duplication since rust doesn't permit cfg_attr(not(all(loom, test)), const).

[NobodyXu]

Test injection_queue_depth failed in windows CI, I don't think this is caused by this PR and I will open an issue for this.

[Darksonn]

Thanks. I've restarted the failed CI jobs.

[NobodyXu]

I've removed the tokio_no_const_mutex_new cfg from CI but it seems that the repository is set to depends on cross-test-with-parking_lot (armv5te-unknown-linux-gnueabi, --cfg tokio_no_const_mutex_new) and cross-test-without-parking_lot (armv5te-unknown-linux-gnueabi, --cfg tokio_no_const_mutex_new).

[Darksonn]

I've removed those checks from the list of required checks.

[NobodyXu]

I've removed those checks from the list of required checks.

Thanks!

Now CI is green.

[Darksonn]

Thanks.