C issues:

[billbrod]

In conda-forge/staged-recipes#25506, the OSX build of pyrtools was failing because of a compilation error in the C code (which uses gcc in our deploy action here, but clang16 in the conda build).

I installed clang=16 from conda-forge in a new conda environment, then ran CC=clang pip install . in a clean version of the repo (which forced the compilation to use clang, see setuptools docs), and was able to reproduce the error (if uninstalling and reinstalling, in order to try possible solutions, must also delete the build/ directory that gets created by pip install; adding -vvv will cause the output to include the compilation command, also useful for debugging).

The issue was the x_stop and y_stop did not have a type declared: parameter 'y_stop' was not declared, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int]

I also removed unused i,j, which were raising a warning. There are many other warnings, largely about function definitions without prototypes, and I don't understand C well enough to fix them. Writing out these notes in case we need to come back and fix them at some point.

[billbrod]

After this is merged, will update the version on pypi and then trigger the conda build again.