Update when_all to operate on IoAwaitable

[mvandeberg]

Summary by CodeRabbit

• Refactor
  • Updated when_all API to accept IoAwaitables directly instead of exclusively task types, enabling composition with a broader range of awaitable types.

[coderabbitai]

📝 Walkthrough

Walkthrough

A detail-level type alias awaitable_result_t is added to extract awaitable result types via await_resume(). The when_all API is refactored from accepting task<Ts>... to accepting IoAwaitable... As, updating its public signature, internal state representation, and storage. The same type alias is removed from when_any to avoid duplication.

Changes

Cohort / File(s)	Summary
Type Extraction Infrastructure include/boost/capy/concept/io_awaitable.hpp	Adds detail-level type alias awaitable_result_t<A> that extracts result type by invoking await_resume() on a decayed awaitable reference.
when_all Awaitable Refactor include/boost/capy/when_all.hpp	Refactors when_all API from task-centric to awaitable-centric: public function signature changes from when_all(task<Ts>... tasks) to when_all(As... awaitables) with IoAwaitable constraint; result type calculation updated to use awaitable_result_t<As>...; internal state storage, frame storage, launcher adapters, and dispatch flow all switched from task-based to awaitable-based; documentation and parameter descriptions updated accordingly.
Type Alias Deduplication include/boost/capy/when_any.hpp	Removes detail-level awaitable_result_t type alias (now centralized in io_awaitable.hpp).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Feature: when_any #101: Directly related through shared use of awaitable_result_t and awaitable-based combinator APIs; implements when_any which previously defined the type alias now extracted to io_awaitable.hpp.

Poem

🐰 Awaitables hop in with grace,
Tasks yield to a better place,
Type aliases extracted, deduplicated clean,
When_all now sees what all have seen! ✨

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main objective: refactoring when_all to operate on IoAwaitable entities instead of task types, which is the primary change across all modified files.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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No actionable comments were generated in the recent review. 🎉

🧹 Recent nitpick comments

include/boost/capy/when_all.hpp (1)

400-448: Consider documenting parent-cancellation propagation and @throws behavior.

The javadoc is well-written and covers concurrency, result ordering, and the first-exception-wins policy. Two gaps relative to the coding guidelines for async/awaitable function javadoc:

1. Cancellation support: The launcher (line 310‑323) propagates the parent's stop_token to children, but the doc doesn't mention that callers can cancel when_all via a parent stop token (and that the resulting error compares equal to capy::cond::canceled).
2. @throws: The function rethrows the first child exception (line 468‑469), which could be documented with a @throws clause.

As per coding guidelines: "Document cancellation support in async/awaitable function javadoc" and "Document @throws in async/awaitable function javadoc for precondition violations".

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[cppalliance-bot]

An automated preview of the documentation is available at https://146.capy.prtest3.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-02-10 18:51:34 UTC

[cppalliance-bot]

GCOVR code coverage report https://146.capy.prtest3.cppalliance.org/gcovr/index.html
LCOV code coverage report https://146.capy.prtest3.cppalliance.org/genhtml/index.html
Coverage Diff Report https://146.capy.prtest3.cppalliance.org/diff-report/index.html

Build time: 2026-02-10 19:00:15 UTC