Bug summary
Two ways of generating a matplotlib plot in our package started producing images with slightly different dimensions since the 3.11.0 release, using the macosx backend. Switching to the agg backend makes the problem disappear.
I know I can't provide an actual MWE since I don't own a mac device, but maybe someone has an idea what is happening based on the diff image?
Code for reproduction
Actual outcome
Expected outcome
We expect the two images to be the same.
Additional information
Since the 3.11 release, the CI pipelines for our scientific python package have been failing for the macos builds only. Our testsuite fails on some image comparison tests, that checks if two different ways to create a plot result in the same outcome. These tests used to pass for a long time, across multiple matplotlib versions. They still pass in our linux pipelines. But after the 3.11 release, they started failing on macos, because the vertical image dimensions differ by 2 pixels. I also compared the resulting images and there are also tiny differences in the rendering.
You can see the output log here at the bottom: https://gitlab.com/ifosim/finesse/finesse3/-/jobs/14970136713
Operating system
OS/X
Matplotlib Version
3.11.0
Matplotlib Backend
macosx
Python version
3.11 till 3.14
Jupyter version
No response
Installation
conda
Bug summary
Two ways of generating a matplotlib plot in our package started producing images with slightly different dimensions since the 3.11.0 release, using the macosx backend. Switching to the agg backend makes the problem disappear.
I know I can't provide an actual MWE since I don't own a mac device, but maybe someone has an idea what is happening based on the diff image?
Code for reproduction
Actual outcome
Expected outcome
We expect the two images to be the same.
Additional information
Since the 3.11 release, the CI pipelines for our scientific python package have been failing for the macos builds only. Our testsuite fails on some image comparison tests, that checks if two different ways to create a plot result in the same outcome. These tests used to pass for a long time, across multiple matplotlib versions. They still pass in our linux pipelines. But after the 3.11 release, they started failing on macos, because the vertical image dimensions differ by 2 pixels. I also compared the resulting images and there are also tiny differences in the rendering.
You can see the output log here at the bottom: https://gitlab.com/ifosim/finesse/finesse3/-/jobs/14970136713
Operating system
OS/X
Matplotlib Version
3.11.0
Matplotlib Backend
macosx
Python version
3.11 till 3.14
Jupyter version
No response
Installation
conda