Hello Python packagers.
After touching the %python_provide topic in:
https://lists.fedoraproject.org/archives/list/python-devel@xxxxxxxxxxxxxxxxxxxxxxx/thread/SSJLPWSGFGPYRSHXQZDR7JNQXSDGGX3Z/
I have realized several things I don't like about %python_provide:
1) It must be used conditionally (it is not defined in python-srpm-macros).
That means you always wrap it in %{?python_provide:...} in order to have a
"valid" specfile even when the macro is not yet defined (e.g. during SRPM
creation in Koji or on a packager's machine without python-rpm-macros installed).
2) You cannot use it with arbitrary versions. Suppose you package python3-foo
1.0 but you want to provide python3-bar 2.0 for some reason -- this is not very
common, but it happens. %python_provide only takes the "name" as an argument,
always using %{?epoch} %{version} and %{release}.
3) You need to both add a virtual provide + use the macro. Suppose you want to
provide python3-pkg_resources from python3-setuptools. Currently, you need to add:
Provides: python3-pkg_resources = %{version}-%{release}
%{?python_provide:%python_provide python3-pkg_resources}
4) When used with (sub)package name, it generates a duplicate dependency on
Fedora 33+ (and an rpmlint error).
5) It produces Obsoletes, but that might no longer be necessary nor desired.
6) Broken expectations about %_isa. It used to add %_isa provides based on wrong
data, it no longer does that (except on old releases and EPELs), can be used
manually with name%{?_isa}, but not on the old releases.
7) Undocuemnted error handling (e.g. the macro expands to nothing when used with
pypy-foo, but errors when used with foo).
Hence, I was thinking (for the sake of backwards compatibility) to provide a new
mechanism to do this and preserve the old macro as is, deprecating it in Fedora
36-ish, actually maybe removing it once RHEL 9 goes EOL (or never, which is
basically the same from today's perspective).
The new macro should solve the problems from above, my current (quick, untested)
ideas are:
1) Define the macro in python-srpm-macros. No need to use it conditionally. We
can backport it to EPEL 8 and define a "stub" macro in EPEL 7 and 6. (An if we
start using the macro only after Fedora 30 goes EOL, we can make the macro
behave consistently across all Fedora versions.)
2) Accept version identifier as an optional argument, use %{?epoch} %{version}
and %{release} as default. (See for example %{pypi_source} on how this can be done.)
3) Make the macro also produce the provide for the given name and document that.
E.g. when you call it with python3-pkg_resources, it also provides
python3-pkg_resources (not only python-pkg_resources etc.).
4) Make it so that for given arguments, the macro will only expand to something
once per build. Hence when you use it with package name, the automatic provides
won't re-add the same provide again. This also means you cannot have 2 different
(sub)packages provide the same name-version-release, but that shall be very very
very uncommon need and can always be workarounded somehow if needed.
5) No obsoletes with the new macro. Packagers use manual obsoletes when desired.
6) Document clearly that there is no %{?_isa} (and there is no "backwards
compatibility" load to carry). When absolutely desired, packagers can call the
macro with %{name}%{?_isa}.
7) Support arbitrary names. Only provide the given name and nothing else if not
"recognized".
As a bonus, I think the current if-elif-elif-elif-elif code can be replaced with
lua patterns (imagine regex).
As always, this leaves us with the name problem, but I'd very much like to use
%python_provides (note the s). The only problem I see is that it is likely to be
mistaken for the old one, but IMHO it shouldn't really hurt that much.
Usage example:
%package -n python3-setuptools
%python_provides python3-pkg_resources
Resulting provides:
python3-setuptools = 46.6.6-6.fc33
python-setuptools = 46.6.6-6.fc33
python39-pkg_resources = 46.6.6-6.fc33
python3-pkg_resources = 46.6.6-6.fc33
python-pkg_resources = 46.6.6-6.fc33
python39-pkg_resources = 46.6.6-6.fc33
Another example:
%package -n python3-pillow
%python_provides python3-PIL 1.1.6-100
Resulting provides:
python3-pillow = 7.1.1-1.fc33
python-pillow = 7.1.1-1.fc33
python39-pillow = 7.1.1-1.fc33
python3-PIL = 1.1.6-100
python-PIL = 1.1.6-100
python39-PIL = 1.1.6-100
Dummy when used with package name:
%package -n python3-pip
%python_provides python3-pip
Provides:
python3-pip = 20.0.2-1.fc33
python-pip = 20.0.2-1.fc33
python39-pip = 20.0.2-1.fc33
(all of them only once)
Any name is OK:
%python_provides wroom 666
Provides:
wroom = 666
What do you think?
--
Miro Hrončok
--
Phone: +420777974800
IRC: mhroncok
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