Dear fellow Debian Python and Science maintainers, I am pleased to announce that I am almost ready to start thetransition to NumPy 2. A preliminary release of NumPy 2.1.0 is in experimental already, I'm just waiting for the resolution of #1076236 [1] and the necessary NEW roundtrip before I request a transition slot from the Release Team for the required rebuild of all binary extensions.
[1] https://bugs.debian.org/1076236I have a few remarks for the maintainers of NumPy reverse dependencies; everyone else feel free to skip the rest of this email.
a) I expect that many upstream releases are NumPy 2 ready at this point, but needless to say, the major version bump comes with extensive cleanup of legacy APIs. Old stuff might break.
b) For binary Python extensions, the NumPy developers have reset the ABI counter: the latest NumPy 1 ABI 9 is succeeded by NumPy 2 ABI 0. This is reflected in a new virtual package name, python3-numpy2-abi0 (note the additional "2" in the name). The API counter, on the other hand, has not been reset and just bumped to 19.
c) Speaking of ABI breakage, while binary extensions built against NumPy 1.x will not work with NumPy 2, everything rebuilt against NumPy 2 is currently binary compatible with NumPy 1.25 and newer. Therefore, ${numpy3:Depends} will usually resolve to "python3-numpy2-abi0 | python3-numpy-abi9" for binary extensions.
d) Related to the previous point, I deliberately dropped the constraint "python3-numpy (>= min-api-version)" for binary extensions. In my experience, the C API version has very little bearing on whether or not a module can be imported with a particular NumPy version; in fact, arch:all packages never had a version restriction for "python3-numpy" despite the Python API being much more exposed than the C API. As corroborating evidence, the SciPy 1.13.1-5 package rebuilt against NumPy 2 still passes its test suite with the trixie autopkgtest and NumPy 1. Nevertheless, dh_numpy3 in strict mode will continue to add a dependency for the current API version, and you can always add an explicit versioned dependency on "python3-numpy" to your binary package if need be.
Cheers Timo -- ⢀⣴⠾⠻⢶⣦⠀ ╭────────────────────────────────────────────────────╮ ⣾⠁⢠⠒⠀⣿⡁ │ Timo Röhling │ ⢿⡄⠘⠷⠚⠋⠀ │ 9B03 EBB9 8300 DF97 C2B1 23BF CC8C 6BDD 1403 F4CA │ ⠈⠳⣄⠀⠀⠀⠀ ╰────────────────────────────────────────────────────╯
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