ci: reduced runs on draft PRs

[henryiii]

Description

This reduces the runs on draft PRs. I've also now listed all jobs explicitly, which should help both expand the variations we test, and reduce the repeated testing.

• ci: reduce runs on draft PRs
• ci: list all jobs explicitly
• tests: support C++23 in tests
• ci: rename cibw workflow file
• tests: add PYBIND11_TEST_SMART_HOLDER to tests

Suggested changelog entry:

• Support Windows C++20 and Linux C++23 in tests

[rwgk]

I didn't look in detail, but I sure love the high-level direction.

I sent this prompt to ChatGPT:

---

I'm looking at this PR:

#5707

I only have very limited experience working on .github/workflows files.

High-level question: Is the file organization idiomatic?

What's on my mind: .github/workflows/ci.yml is basically a top-level workflow, while the new .github/workflows/reusable-standard.yml appears to be a akin to a helper function. My first instinct would be to put helpers into another directory, e.g. subdirectory.

---

• https://chatgpt.com/share/6839dee3-ddd4-8008-8964-a43de992b220

---

It suggests adding a comment (I'd say not needed), and a slightly different filename:

reusable-ci-standard.yml

I like that, but what you have seems fine, too.

[henryiii]

It's all ci, so not sure ci makes much sense here. We should probably rename ci.yml to tests.yaml, then reusable-tests-standard isn't bad. (we should also standardize on yml vs. yaml, we've got one yaml). I've mostly seen these as reusable- prefixed and not in subdirectories (not sure what the requirements are, they might have to be top level for all I know).

[rwgk]

It's all ci, so not sure ci makes much sense here. We should probably rename ci.yml to tests.yaml, then reusable-tests-standard isn't bad. (we should also standardize on yml vs. yaml, we've got one yaml). I've mostly seen these as reusable- prefixed and not in subdirectories (not sure what the requirements are, they might have to be top level for all I know).

Sounds great to me, not in this PR I guess?

I think I'd pick build_and_test.yml as the new name.

[henryiii]

I like short¹, especially if it was to be in the reusable filename too. How can you test without building, isn't that implied?

Currently working on getting the CI check names shorter, as you can't read anything past a certain length in the GitHub UI. It's adding both names together with the params added too...

Footnotes

1. Within limits. classh is too short. :P ↩

[rwgk]

How can you test without building, isn't that implied?

I'm totally fine if you want to keep it short.

Just to explain:

In cuda-python, we build first, separately, then run tests from another workflow, using the artifacts from the build step (for more platforms than we build with).

With that mindset: if I see "test.yml", the question pops up: where do we build?

[henryiii]

Pybind11 doesn't have anything to build; libraries with a built component this makes more sense than a header-only library where tests are what you are building; they are the only thing you are building.

[Copilot]

Pull Request Overview

This PR reduces CI runs on draft pull requests, lists all jobs explicitly, and enhances test support for C++23 and a new “smart holder” mode.

• Add PYBIND11_TEST_SMART_HOLDER option and compile-time flags to test CMake configurations
• Introduce a reusable CI workflow and adjust ci.yml/configure.yml to skip draft PRs and split standard jobs
• Update tests to use C++23 features and alignas-based buffers, and rename workflows for clarity

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/test_embed/CMakeLists.txt	Added conditional add_compile_definitions for smart-holder flag
tests/test_cmake_build/CMakeLists.txt	Added conditional add_compile_definitions in build tests
tests/pure_cpp/smart_holder_poc_test.cpp	Included <cstddef> and replaced aligned_storage with alignas raw-byte array
tests/CMakeLists.txt	Introduced PYBIND11_TEST_SMART_HOLDER option and per-target flags
.github/workflows/reusable-standard.yml	New reusable “standard test” workflow
.github/workflows/configure.yml	Skip cmake job on draft PRs and expand pull_request types
.github/workflows/ci.yml	Split standard into small/large, integrate reusable workflow, skip draft PRs

Comments suppressed due to low confidence (3)

tests/CMakeLists.txt:504

• Consider using PRIVATE instead of PUBLIC for test-only compile definitions to avoid leaking flags into dependent targets.

target_compile_definitions(${target} PRIVATE -DPYBIND11_TEST_BOOST)

tests/CMakeLists.txt:583

• [nitpick] These repeated compile definition calls could be consolidated (e.g., via a function or variable) to reduce duplication and simplify future updates.

target_compile_definitions(mod_per_interpreter_gil PUBLIC -DPYBIND11_RUN_TESTING_WITH_SMART_HOLDER_AS_DEFAULT_BUT_NEVER_USE_IN_PRODUCTION_PLEASE)

.github/workflows/ci.yml:212

• The matrix variable args no longer exists; this placeholder should reference matrix.cmake-args or be removed to avoid an empty job name.

name: Configure C++11 ${{ matrix.args }}

[Copilot]

Pull Request Overview

This PR reduces unnecessary CI runs on draft pull requests while also expanding the explicit listing of jobs and enabling C++23 and smart holder support in tests. Key changes include:

• Adding conditions to GitHub Actions workflows to bypass execution on draft PRs.
• Updating test cases and CMake configuration to support C++23 and the PYBIND11_TEST_SMART_HOLDER option.
• Refining job matrices and configuration settings across multiple CI workflow files.

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/test_pytypes.cpp	Updated lambda parameters for better const-correctness and efficient iteration.
tests/test_embed/CMakeLists.txt	Added compile definitions for smart holder testing based on PYBIND11_TEST_SMART_HOLDER.
tests/test_cmake_build/CMakeLists.txt	Similarly added conditional compile definitions for smart holder support.
tests/pure_cpp/smart_holder_poc_test.cpp	Replaced aligned storage with an alignas-based raw byte array for memory block allocation.
tests/CMakeLists.txt	Introduced an option to toggle smart holder testing and applied corresponding definitions.
CMakePresets.json	Added settings such as CMAKE_COLOR_DIAGNOSTICS to enhance diagnostic output.
.github/workflows/reusable-standard.yml	Provided a reusable workflow for standard tests with updated job inputs.
.github/workflows/configure.yml	Added conditions to only run configuration when a PR is not in draft state.
.github/workflows/ci.yml	Modified job definitions and matrix entries to reduce CI runs on draft PRs and adjust flags.

Comments suppressed due to low confidence (1)

.github/workflows/ci.yml:171

• For clarity and consistency, consider renaming the 'python' key in the 'inplace' job matrix to 'python-version', matching the naming used in other jobs.

inplace:
    matrix:
      include:
        - runs-on: ubuntu-latest
          python: '3.9'

[henryiii]

Okay, fixed tests in C++20 on Windows, C++23. Added color compile output.

For clarity and consistency, consider renaming the 'python' key in the 'inplace' job matrix to 'python-version', matching the naming used in other jobs.

I like this, but let's do it in a followup instead of rebuilding this one again.