From `python3-foo` packages automatically generate `python3.X-foo` Obsoletes tags on CentOS/RHEL

python-rpm-generators.spec

@@ -1,7 +1,7 @@
 Name:           python-rpm-generators
 Summary:        Dependency generators for Python RPMs
 Version:        12
-Release:        12%{?dist}
+Release:        13%{?dist}
 
 # Originally all those files were part of RPM, so license is kept here
 License:        GPLv2+
@@ -25,7 +25,7 @@ Requires:       python3-packaging
 # We have parametric macro generators, we need RPM 4.16 (4.15.90+ is 4.16 alpha)
 Requires:       rpm > 4.15.90-0
 # This contains the Lua functions we use:
-Requires:       python-srpm-macros >= 3.8-5
+Requires:       python-srpm-macros >= 3.10-15
 
 %description -n python3-rpm-generators
 %{summary}.
@@ -47,6 +47,10 @@ install -Dpm0755 -t %{buildroot}%{_rpmconfigdir} *.py
 %{_rpmconfigdir}/pythonbundles.py
 
 %changelog
+* Wed Jan 26 2022 Tomas Orsava <torsava@redhat.com> - 12-13
+- From `python3-foo` packages automatically generate `python3.X-foo` Obsoletes
+  tags on CentOS/RHEL
+
 * Fri Jan 21 2022 Fedora Release Engineering <releng@fedoraproject.org> - 12-12
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_36_Mass_Rebuild
 

pythonname.attr

@@ -16,4 +16,27 @@
     end
 }
 
+%__pythonname_obsoletes() %{?rhel:%{lua:
+    -- On CentOS/RHEL we automatically generate Obsoletes tags in the form:
+    --   package python3-foo -> Obsoletes: python3.XY-foo
+    -- This provides a clean upgrade path between major versions of CentOS/RHEL.
+    -- In Fedora this is not needed as we don't ship ecosystem packages
+    -- for alternative Python interpreters.
+    local python = require 'fedora.srpm.python'
+    -- this macro is called for each file in a package, the path being in %1
+    -- but we don't need to know the path, so we would get for each file: Macro %1 defined but not used within scope
+    -- in here, we expand %name conditionally on %1 to suppress the warning
+    local name = rpm.expand('%{?1:%{name}}')
+    local evr = rpm.expand('%{?epoch:%{epoch}:}%{version}-%{release}')
+    local obsoletes = python.python_altobsoletes_once(name, evr)
+    -- obsoletes is either an array/table or nil
+    -- nil means the function was already called with the same arguments:
+    --   either with another file in %1 or manually via %py_provides
+    if obsoletes then
+      for i, obsolete in ipairs(obsoletes) do
+          print(obsolete .. ' ')
+        end
+    end
+}}
+
 %__pythonname_path ^/