Cmake update appears to break compilation

[fnmut]

I'm seeing this error during a build:

22.60     | CMake Error at src/h3lib/CMakeLists.txt:15 (cmake_minimum_required):
22.60     |   Compatibility with CMake < 3.5 has been removed from CMake.
22.60     |
22.60     |   Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
22.60     |   to tell CMake that the project requires at least <min> but has been updated
22.60     |   to work with policies introduced by <max> or earlier.
22.60     |
22.60     |   Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.

It appears cmake updated yesterday to version 4.0. I think this introduces this compatibility issue.

[ajfriend]

Thanks for flagging! For now, I suppose we can just handle this by pinning the cmake version < 4

[ajfriend]

Actually, how are you building this? I didn't run into the issue building locally just now.

[BenDRoberson]

I am seeing this error in a CI build as well but I'm using an older version of h3 and not cmake version 4.0+.

• my image is based on Ubuntu 20.04
• h3 version is 3.7.7 - but works on versions >=4 for me. We have some dependencies that don't work on 4.0+ hence version 3.7.7
• cmake version 3.16.3

error is exactly the same and I was able to make it build by updating the minimum version for cmake:

• CMAKE_POLICY_VERSION_MINIMUM=3.5 allows it to build successfully
• Alternatively manually updating src/h3lib/CMakeLists.txt to a minimum version of 3.5 with a find-replace also worked.

Looks like older h3-py builds didn't explicitly set the minimum and that's probably causing the problem - maybe cmake changed from just a warning to an error recently?

[fnmut]

maybe cmake changed from just a warning to an error recently?

Yep it appears that is the case, and PyPi cmake got updated to 4.0 late last week.

Your suggestion to use CMAKE_POLICY_VERSION_MINIMUM=3.5 does resolve the issue though, so thank you.

but I'm using an older version of h3 and not cmake version 4.0+

We're also using an older version (3.7.6). The error output contains:

8.483     | An error occurred while configuring with CMake.
8.483     |   Command:
8.483     |     /tmp/tmp_tk0bqml/.venv/lib/python3.12/site-packages/cmake/data/bin/cmake /tmp/tmpupm7xrjn/h3-3.7.6

Which made me think it was using a version installed to /tmp. I made several attempts on Friday to get h3 to use a locally installed cmake (whether through system packages or PyPi) and it did not seem to want to use anything else. It's very possible I missed something obvious though.

Looks like older h3-py builds didn't explicitly set the minimum and that's probably causing the problem

My understanding is that's what this is, but it doesn't seem to be respected...

Actually, how are you building this? I didn't run into the issue building locally just now.

Here is a minimal repro dockerfile:

FROM python:3.12

RUN curl -sSL https://install.python-poetry.org | POETRY_HOME=/opt/poetry python3 - && \
    cd /usr/local/bin && \
    ln -s /opt/poetry/bin/poetry && \
    poetry config virtualenvs.create false
                                                           WORKDIR /app

RUN poetry init --name "my_project" \
    --python "^3.12" \
    --no-interaction

RUN poetry add h3==3.7.6

docker buildx build --platform linux/amd64 .

edit:

In fact, the poetry stuff is unnecessary, it looks like you just can't install the older versions in a clean environment.

FROM python:3.12

WORKDIR /app

RUN pip install h3==3.7.6

[BenDRoberson]

Looks like older h3-py builds didn't explicitly set the minimum and that's probably causing the problem

My understanding is that's what this is, but it doesn't seem to be respected...

You're right I should have been more explicit - looks like the syntax changed from cmake_minimum_required(VERSION 3.7.2) to cmake_minimum_required(VERSION 3.15...3.26). For some reason the version seems to be respected now when you give both a min and a max, but isn't in the old version (at least as best I can tell right now)