Incompatible with Cython 3 due to division semantics

[musicinmybrain]

Cython 3.0.0 was released, and indexed_gzip is not quite compatible.

=================================== FAILURES ===================================
________________________________ test_read_all _________________________________
[gw7] linux -- Python 3.12.0 /usr/bin/python3

testfile = '/builddir/build/BUILD/indexed_gzip-1.7.1/ctest_zran_15801045_False.gz'
nelems = 15801045, use_mmap = False

    def test_read_all(testfile, nelems, use_mmap):
        for no_fds in (True, False):
>           ctest_zran.test_read_all(testfile, no_fds, nelems, use_mmap)

../../BUILDROOT/python-indexed_gzip-1.7.1-5.fc39.x86_64/usr/lib64/python3.12/site-packages/indexed_gzip/tests/test_zran.py:86:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   nelemsp = nbytes / 8.
E   TypeError: 'float' object cannot be interpreted as an integer

indexed_gzip/tests/ctest_zran.pyx:799: TypeError
__________________________ test_seek_then_read_block ___________________________
[gw2] linux -- Python 3.12.0 /usr/bin/python3

testfile = '/builddir/build/BUILD/indexed_gzip-1.7.1/ctest_zran_15249998_False.gz'
nelems = 15249998, niters = 1000, seed = 497514082, use_mmap = False

    @pytest.mark.slow_test
    def test_seek_then_read_block(testfile, nelems, niters, seed, use_mmap):
        for no_fds in (True, False):
>           ctest_zran.test_seek_then_read_block(
                testfile, no_fds, nelems, niters, seed, use_mmap
            )

../../BUILDROOT/python-indexed_gzip-1.7.1-5.fc39.x86_64/usr/lib64/python3.12/site-packages/indexed_gzip/tests/test_zran.py:91:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
indexed_gzip/tests/ctest_zran.pyx:817: in indexed_gzip.tests.ctest_zran.test_seek_then_read_block
    with open(testfile, 'rb') as pyfid:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   nelemsp = nbytes / 8.
E   TypeError: 'float' object cannot be interpreted as an integer

indexed_gzip/tests/ctest_zran.pyx:858: TypeError
---------------------------- Captured stdout setup -----------------------------
Seed for random number generator: 497514082
----------------------------- Captured stdout call -----------------------------
0 / 1000: reading 3257996 elements from 9244320 ...

The obvious issue here is that Cython 3 aligns division semantics with Python 3, so x / y always produces a Python float even where x and y are both Python integers. This could be rewritten as x // y to produce an integer.

I could offer a PR for the particular cases showing up in the test failures, but it might be best for someone more familiar with the code to review uses of the / operator throughout the various .pyx files.

[pauldmccarthy]

Hi @musicinmybrain, thanks for the report - the only offending division operations are in the unit tests. I'm hoping to have a new release out today, with fixes for this and for #126.

[musicinmybrain]

Awesome, thanks!