Align Executor concept and executor_ref with P4003

[mvandeberg]

• Executor concept: pass continuation by reference in requires-expression to match stable-address semantics of all implementations
• executor_ref constructor: constrain to Executor to reject non-conforming types at the call site instead of deferring to vtable instantiation
• executor_ref::target(): add noexcept to both overloads (trivially non-throwing type-id comparison and static_cast)

Summary by CodeRabbit

• Refactor
  • Updated executor concept parameter binding requirements
  • Enhanced exception safety with noexcept annotations to executor reference methods

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 3a94ad25-7b35-4e89-908d-62062ba7591e

📥 Commits

Reviewing files that changed from the base of the PR and between 8c2ca12 and c0988e2.

📒 Files selected for processing (2)

• include/boost/capy/concept/executor.hpp
• include/boost/capy/ex/executor_ref.hpp

---

📝 Walkthrough

Walkthrough

The PR refines the Executor concept by requiring dispatch/post methods to accept a non-const lvalue reference for continuation parameters, and strengthens executor_ref's constructor constraint while adding noexcept qualifiers to target() methods.

Changes

Cohort / File(s)	Summary
Executor Concept Refinement include/boost/capy/concept/executor.hpp	Modified Executor concept's requires clause to bind the last parameter of dispatch/post as a non-const lvalue reference (continuation& c instead of continuation c), tightening concept satisfaction rules.
Executor Reference Enhancements include/boost/capy/ex/executor_ref.hpp	Added #include <boost/capy/concept/executor.hpp>, strengthened executor_ref(Ex const&) constructor template constraint with Executor<Ex> requirement, and added noexcept qualifiers to both target() const and target() method signatures.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• The usual suspects #125: Modifies the Executor concept's dispatch/post requirements, directly related to the concept parameter binding changes in this PR.
• Add target() to executor_ref and execution_context #154: Introduces target() accessor methods on executor_ref; this PR refines their signatures by adding noexcept qualifiers.
• Prepare Capy for Review #96: Performs broad refactoring of executor-related APIs including executor_ref and executor concepts, overlapping with the constraint and signature updates made here.

Poem

🐰 Hoppity-hop, the executor's refined,
Lvalue references now rightly bind,
Concepts tighten, noexcept gleams,
Carrots of safety in our type-checked dreams! 🥕✨

🚥 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 'Align Executor concept and executor_ref with P4003' accurately summarizes the main change, which involves aligning the Executor concept and executor_ref with P4003 specifications.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[cppalliance-bot]

An automated preview of the documentation is available at https://250.capy.prtest3.cppalliance.org/index.html

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

2026-04-01 22:51:51 UTC

[cppalliance-bot]

GCOVR code coverage report https://250.capy.prtest3.cppalliance.org/gcovr/index.html
LCOV code coverage report https://250.capy.prtest3.cppalliance.org/genhtml/index.html
Coverage Diff Report https://250.capy.prtest3.cppalliance.org/diff-report/index.html

Build time: 2026-04-01 23:07:04 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.47%. Comparing base (8c2ca12) to head (c0988e2).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #250      +/-   ##
===========================================
- Coverage    92.50%   92.47%   -0.03%     
===========================================
  Files          170      170              
  Lines         9348     9348              
===========================================
- Hits          8647     8645       -2     
- Misses         701      703       +2     

Flag	Coverage Δ
linux	92.46% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
include/boost/capy/ex/executor_ref.hpp	85.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8c2ca12...c0988e2. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.