feat(Async): StartTaskImmediate

[bartelink]

Addresses the task start+await aspect of fsharp/fslang-suggestions#1284

See also fsharp/fslang-suggestions#1467

Checklist

• Test cases added
• Update Await/AwaitTask xmldoc to mention that this is how you tie in cancellation
• self review
• Release notes entry updated
• Close Add Async.AwaitTask overloads which helps with CancellationToken passing, and a new warning fsharp/fslang-suggestions#1284 ?

[github-actions]

❗ Release notes required

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✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
`src/FSharp.Core`	docs/release-notes/.FSharp.Core/11.0.100.md

[Copilot]

Pull request overview

This PR introduces Async.StartTaskImmediate, a new FSharp.Core API that runs a task factory with the ambient Async.CancellationToken and then awaits the produced task/task-like value using Async.Await (non-AggregateException wrapping) semantics. It also updates documentation and unit tests to cover the new behavior and updates the public-surface baselines and release notes accordingly.

Changes:

• Add Async.StartTaskImmediate overloads for Task, Task<'T>, ValueTask, ValueTask<'T>, plus an SRTP-based overload for task-like .GetAwaiter() values.
• Update Await/AwaitTask xmldoc to point users to StartTaskImmediate for the “start + await with cancellation” scenario.
• Add/extend unit tests and update surface area baselines + release notes.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/AsyncType.fs	Adds coverage for StartTaskImmediate across Task/ValueTask and task-like awaitables.
tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.release.bsl	Updates netstandard2.1 release surface area baseline for the new APIs.
tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.debug.bsl	Updates netstandard2.1 debug surface area baseline for the new APIs.
tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.release.bsl	Updates netstandard2.0 release surface area baseline for the new Task-only APIs.
tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.debug.bsl	Updates netstandard2.0 debug surface area baseline for the new Task-only APIs.
src/FSharp.Core/async.fsi	Adds public API declarations and xmldoc for StartTaskImmediate, plus cross-references from Await/AwaitTask.
src/FSharp.Core/async.fs	Implements StartTaskImmediate in terms of binding Async.CancellationToken and awaiting via Async.Await.
docs/release-notes/.FSharp.Core/11.0.100.md	Adds a release note entry for Async.StartTaskImmediate.

Suppressed comments (1)

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/AsyncType.fs:906

• This new test module should also be part of NotThreadSafeResourceCollection, otherwise it may run in parallel with tests that mutate the global default cancellation token (Async.CancelDefaultToken), causing nondeterministic failures.

module AsyncStartTaskImmediateTaskLikeTests =

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[bartelink]

@T-Gro I hit the merge button on the PR page around the time you approved, which seems to have mangled things - have force-pushed a fresh (local) merge. I've yet to do a local build and/or validate it's actually any more healthy (the conflict was in the release notes but it appears that surface area tests are failing, which I guess you understand re the net10.0 TFM changes - I put NET in the #ifdefs but maybe !NETFRAMEWORK is better?) Silenced build fails post merge by adding | NET to NETSTANDARD_21 in guards to correct baseline validation re net10 package validation (maybe that should be !NETFRAMEWORK instead)

[T-Gro]

The ifdef guard is correct, thanks for actioning this !

Pls let me know if I am owing any other reviews - I believe we might be finished with all the Async/Task/Value task improvements for NET11 by now? 🥇 👍

[bartelink]

Thanks for shepherding these through, great to see them in!

Pls let me know if I am owing any other reviews

@T-Gro these were my notes regarding potential additions fsharp/fslang-suggestions#1467 (comment)

I personally have a fondness for startAsyncImmediate (piping and forcing a CT to be supplied is very unintuitive IME without it and tends to be wrong in most codebases)

The parallelDo for Async pops up in every codebase IME. And once you have Async.Parallel you want the Task equivalent and its easy to forget cancellation so I think that impl (plus the cancellable task ehancements in that other PR are subtle enough to help enough people - having to drag in FsToolkit.ErrorHandling is very annoying for a relatively common thing)

All that said I do know your previous attitude has been to defer that from this batch of things - if that remains your stance, I might fork off a new pair of suggestions (this also would allow me to close the temp issues in TaskSeq thatnhave sat there annoying the RepoAssist bot for years!)