pybind11: add version 3.0.0 by tttapa · Pull Request #28174 · conan-io/conan-center-index

tttapa · 2025-08-15T14:22:20Z

Summary

Changes to recipe: pybind11/3.0.0

Motivation

Adds the latest version: https://github.com/pybind/pybind11/releases/tag/v3.0.0

Details

The new version has been added to config.yml and conandata.yml.
One of the patches to tools/pybind11Common.cmake is no longer necessary since the if(TARGET ...) guard logic was removed in pybind/pybind11@28dbce4.

Read the contributing guidelines
Checked that this PR is not a duplicate: list of PRs by recipe
Tested locally with at least one configuration using a recent version of Conan

Signed-off-by: Uilian Ries <uilianr@jfrog.com>

uilianries

@tttapa Thank you for your PR!

The new major version comes with a ton of changes, but in terms of building, it looks okay: pybind/pybind11@v2.13.6...v3.0.0#diff-1e7de1ae2d059d21e1dd75d5812d5a34b0222cef273b7c3a2af62eb747f9d20a

I also made a few changes in your PR, adapting to a lighter revision. Cheers!

tttapa

I've added two comments and pushed corresponding commits to address them. Let me know if any further changes are necessary.

tttapa · 2025-08-19T13:15:55Z

 cmake_minimum_required(VERSION 3.15)
 project(test_package LANGUAGES CXX)

+find_package(PythonInterp REQUIRED)


It may be better to use the FindPython module instead of the (long deprecated) FindPythonInterp module:
https://pybind11.readthedocs.io/en/stable/cmake/index.html#modes

Good catch!

tttapa · 2025-08-19T13:39:45Z

        cmake.build()

-    @property
    def _python_interpreter(self):


This doesn't work for me because I have multiple versions of Python installed. CMake locates Python 3.14, whereas python3 in the PATH is Python 3.10 (this is the system-wide default on Ubuntu 22.04). To fix this, we should use the ${Python_EXECUTABLE} selected by CMake to run the tests.

@tttapa We have multiple Python versions installed in the CI, too. In order to make sure which version should be used, we manipulate the PATH in the profile:

[buildenv] PATH=+(path)/opt/pyenv/versions/3.12.7/bin/ [runenv] PATH=+(path)/opt/pyenv/versions/3.12.7/bin/

So we know Python 3.12 will be found first. Please, try a similar approach. Using a well-configured profile ensures you will have no surprises in case you install a new Python version on your machine. Personally, I use pyenv, so I have a bunch of Python versions installed too, so I used profiles to avoid messing around, as usually I need to run more than one Python version when developing Conan or running specific tests.

CMake locates Python 3.14, whereas python3 in the PATH is Python 3.10 (this is the system-wide default on Ubuntu 22.04).

Interesting! this seems odd - though I think CMake tries to locate the most recent python it can find rather than the "default in the current context" one.
If you tweak the test package to pass Python_FIND_UNVERSIONED_NAMES set to FIRST, does it now work? We can probably tweak these variables to make it more consistent for everyone:

Python_FIND_UNVERSIONED_NAMES

Python_FIND_STRATEGY (though I think it this already behaves as we want for policy level >=3.15

we manipulate the PATH in the profile

Unfortunately, this trick does not work if multiple Python versions are installed with the same prefix (e.g. /usr or /usr/local).

I'd argue that it is desirable to have the build and tests succeed without requiring users to tweak their profiles (to modify the path or set FindPython hints). One way to achieve this is by using Python_EXECUTABLE in CMake as in 43663bc, but I'm open to alternatives, of course.

does it work correctly setting Python_FIND_UNVERSIONED_NAMES to First? it should hopefully get CMake to find the first python that it can find PATH

Yes, adding toolchain.variables["Python_FIND_UNVERSIONED_NAMES"] = "FIRST" also works at 1524c40. CMake then selects Python 3.10 as expected.

uilianries · 2025-08-20T07:15:31Z


    def generate(self):
        tc = CMakeToolchain(self)
+        tc.variables["PYBIND11_FINDPYTHON"] = True


@tttapa Why do you need PYBIND11_FINDPYTHON only now? As far as I see, it's active by default: https://github.com/pybind/pybind11/blob/v3.0.0/CMakeLists.txt#L86. What error are you trying to mitigate?

I added it for consistency between the build and the test_package. Setting this variable ensures that they both use FindPython. Otherwise, users may need to provide CMake hints for both FindPythonInterp and FindPython if they want to select a specific interpreter, and a different interpreter may be found during the build and the tests (which AFAICT is fine in the case of pybind11, but it could lead to confusion).
It is indeed active by default in recent versions of pybind11, but the recipe still supports versions <3.12.0, where FindPython is not yet the default.

It also gets rid of the following CMake warning during the build:

CMake Warning (dev) at tools/FindPythonLibsNew.cmake:98 (find_package): Policy CMP0148 is not set: The FindPythonInterp and FindPythonLibs modules are removed. Run "cmake --help-policy CMP0148" for policy details. Use the cmake_policy command to set the policy and suppress this warning. Call Stack (most recent call first): tools/pybind11Tools.cmake:50 (find_package) tools/pybind11Common.cmake:180 (include) CMakeLists.txt:206 (include)

uilianries · 2025-08-20T07:15:36Z


    def generate(self):
        tc = CMakeToolchain(self)
+        tc.variables["PYBIND11_FINDPYTHON"] = True


@tttapa Why do you need PYBIND11_FINDPYTHON only now? As far as I see, it's active by default: https://github.com/pybind/pybind11/blob/v3.0.0/CMakeLists.txt#L86. What error are you trying to mitigate?

uilianries · 2025-08-20T07:16:35Z

 project(test_package LANGUAGES CXX)
+enable_testing()

+find_package(Python REQUIRED COMPONENTS Development OPTIONAL_COMPONENTS Interpreter)


Interpreter should be required; otherwise, we will testing nothing in case it's missing.

The interpreter could be missing when cross-compiling, for example. How should such cases be handled? Explicitly checking for CMAKE_CROSSCOMPILING?
Related: pybind/pybind11#5083 and https://gitlab.kitware.com/cmake/cmake/-/issues/26696

We apply can_run() to avoid running tests when cross-building. Please, check https://github.com/conan-io/conan-center-index/blob/master/docs/package_templates/cmake_package/all/test_package/conanfile.py#L23

We apply can_run() to avoid running tests when cross-building. Please, check https://github.com/conan-io/conan-center-index/blob/master/docs/package_templates/cmake_package/all/test_package/conanfile.py#L23

The problem is that if the interpreter isn't found when cross-building, the test project (the bit that can be crossbuilt), won't be crossbuilt if the interpreter is marked as required, so I think the logic as it is is correct.

tttapa · 2025-08-26T09:04:28Z

@uilianries do you need me to modify or revert any of these changes? Thanks!

uilianries · 2025-08-27T06:40:01Z

@tttapa Thank you for your PR and detailed changes.

* pybind11: add version 3.0.0 * Simplify python interpreter location for testing Signed-off-by: Uilian Ries <uilianr@jfrog.com> * Use python3 for unix Signed-off-by: Uilian Ries <uilianr@jfrog.com> * Use Python interpreter found by cmake Signed-off-by: Uilian Ries <uilianr@jfrog.com> * Stop maintaining old versions Signed-off-by: Uilian Ries <uilianr@jfrog.com> * pybind11: use FindPython module instead of deprecated FindPythonInterp * pybind11: use Python interpreter selected by CMake for tests --------- Signed-off-by: Uilian Ries <uilianr@jfrog.com> Co-authored-by: Uilian Ries <uilianr@jfrog.com>

pybind11: add version 3.0.0

1c1bc95

This was referenced Aug 15, 2025

Updatable recipes qchateau/conan-center-bot#1

Closed

[request] Updatable recipes #3470

Closed

tttapa mentioned this pull request Aug 19, 2025

[service] Unsupported Python version in CI #28198

Closed

uilianries added 4 commits August 19, 2025 11:09

Simplify python interpreter location for testing

a1acb38

Signed-off-by: Uilian Ries <uilianr@jfrog.com>

Use python3 for unix

bfcd2b8

Signed-off-by: Uilian Ries <uilianr@jfrog.com>

Use Python interpreter found by cmake

c655dd1

Signed-off-by: Uilian Ries <uilianr@jfrog.com>

Stop maintaining old versions

4b047e3

Signed-off-by: Uilian Ries <uilianr@jfrog.com>

uilianries previously approved these changes Aug 19, 2025

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AbrilRBS previously approved these changes Aug 19, 2025

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tttapa added 2 commits August 19, 2025 14:40

pybind11: use FindPython module instead of deprecated FindPythonInterp

1524c40

pybind11: use Python interpreter selected by CMake for tests

43663bc

tttapa dismissed stale reviews from AbrilRBS and uilianries via 43663bc August 19, 2025 13:41

tttapa commented Aug 19, 2025

View reviewed changes

uilianries reviewed Aug 20, 2025

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uilianries approved these changes Aug 27, 2025

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jcar87 merged commit d2b4d8a into conan-io:master Aug 27, 2025

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tttapa commented Aug 15, 2025

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uilianries Aug 20, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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tttapa commented Aug 26, 2025

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uilianries commented Aug 27, 2025

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uilianries Aug 20, 2025 •

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