2488353 – Cython fails to build with Python 3.15: Errors found in shards 17, 21, 5, 2, 9: TypeError: not enough arguments for format string + AssertionError: Items in the first set but not the second

Bug 2488353 - Cython fails to build with Python 3.15: Errors found in shards 17, 21, 5, 2, 9: TypeError: not enough arguments for format string + AssertionError: Items in the first set but not the second

Summary: Cython fails to build with Python 3.15: Errors found in shards 17, 21, 5, 2, ...

Keywords:
Status:	NEW
Alias:	None
Product:	Fedora
Classification:	Fedora
Component:	Cython
Sub Component:
Version:	rawhide
Hardware:	Unspecified
OS:	Unspecified
Priority:	unspecified
Severity:	unspecified
Target Milestone:	---
Assignee:	Miro Hrončok
QA Contact:	Fedora Extras Quality Assurance
Docs Contact:
URL:
Whiteboard:
Depends On:
Blocks:	PYTHON3.15 F45FTBFS, RAWHIDEFTBFS
TreeView+	depends on / blocked

Reported:	2026-06-12 14:03 UTC by Karolina Surma
Modified:	2026-06-12 14:03 UTC (History)
CC List:	5 users (show)
Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type:	Bug
Embargoed:
Dependent Products:

Attachments	(Terms of Use)

Description Karolina Surma 2026-06-12 14:03:19 UTC

Cython fails to build with Python 3.15.0b2. Updating to the latest minor version (3.2.5) might solve the issue.

Errors found in shards 17, 21, 5, 2, 9
Errors from shard 17:
======================================================================
FAIL: mod_format_tuple (strmethods_ll2) [1]
Doctest: strmethods_ll2.mod_format_tuple
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/TEST_TMP/17/run/c/strmethods_ll2/strmethods_ll2.cpython-315-x86_64-linux-gnu.so", line 155, in strmethods_ll2.mod_format_tuple
AssertionError: Failed example:
    mod_format_tuple()
Expected:
    Traceback (most recent call last):
    TypeError: not enough arguments for format string
Got:
    Traceback (most recent call last):
      File "<doctest strmethods_ll2.mod_format_tuple[1]>", line 1, in <module>
        mod_format_tuple()
        ~~~~~~~~~~~~~~~~^^
      File "tests/run/strmethods.pyx", line 160, in strmethods_ll2.mod_format_tuple
        return 'abc%sdef' % values
    TypeError: not enough arguments for format string (got 0)
======================================================================
FAIL: mod_format_tuple (strmethods_ll2) [1]
Doctest: strmethods_ll2.mod_format_tuple
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/TEST_TMP/17/run/cpp/strmethods_ll2/strmethods_ll2.cpython-315-x86_64-linux-gnu.so", line 155, in strmethods_ll2.mod_format_tuple
AssertionError: Failed example:
    mod_format_tuple()
Expected:
    Traceback (most recent call last):
    TypeError: not enough arguments for format string
Got:
    Traceback (most recent call last):
      File "<doctest strmethods_ll2.mod_format_tuple[1]>", line 1, in <module>
        mod_format_tuple()
        ~~~~~~~~~~~~~~~~^^
      File "tests/run/strmethods.pyx", line 160, in strmethods_ll2.mod_format_tuple
        return 'abc%sdef' % values
    TypeError: not enough arguments for format string (got 0)
Errors from shard 21:
======================================================================
FAIL: test_python_builtin_compatibility (Cython.Compiler.Tests.TestBuiltin.TestBuiltinCompatibility.test_python_builtin_compatibility)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/Cython/Compiler/Tests/TestBuiltin.py", line 52, in test_python_builtin_compatibility
    self.assertSetEqual(runtime_builtins, expected_builtins)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: Items in the first set but not the second:
'frozendict'
'__lazy_import__'
'sentinel'
'ImportCycleError'
Errors from shard 5:
======================================================================
FAIL: mod_format_tuple (unicodemethods) [1]
Doctest: unicodemethods.mod_format_tuple
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/TEST_TMP/5/run/c/unicodemethods/unicodemethods.cpython-315-x86_64-linux-gnu.so", line 584, in unicodemethods.mod_format_tuple
AssertionError: Failed example:
    mod_format_tuple()
Expected:
    Traceback (most recent call last):
    TypeError: not enough arguments for format string
Got:
    Traceback (most recent call last):
      File "<doctest unicodemethods.mod_format_tuple[1]>", line 1, in <module>
        mod_format_tuple()
        ~~~~~~~~~~~~~~~~^^
      File "tests/run/unicodemethods.pyx", line 589, in unicodemethods.mod_format_tuple
        return u'abc%sdef' % values
    TypeError: not enough arguments for format string (got 0)
======================================================================
FAIL: mod_format_tuple (unicodemethods) [1]
Doctest: unicodemethods.mod_format_tuple
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/TEST_TMP/5/run/cpp/unicodemethods/unicodemethods.cpython-315-x86_64-linux-gnu.so", line 584, in unicodemethods.mod_format_tuple
AssertionError: Failed example:
    mod_format_tuple()
Expected:
    Traceback (most recent call last):
    TypeError: not enough arguments for format string
Got:
    Traceback (most recent call last):
      File "<doctest unicodemethods.mod_format_tuple[1]>", line 1, in <module>
        mod_format_tuple()
        ~~~~~~~~~~~~~~~~^^
      File "tests/run/unicodemethods.pyx", line 589, in unicodemethods.mod_format_tuple
        return u'abc%sdef' % values
    TypeError: not enough arguments for format string (got 0)
Errors from shard 2:
======================================================================
FAIL: mod_format_tuple (strmethods) [1]
Doctest: strmethods.mod_format_tuple
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/TEST_TMP/2/run/c/strmethods/strmethods.cpython-315-x86_64-linux-gnu.so", line 155, in strmethods.mod_format_tuple
AssertionError: Failed example:
    mod_format_tuple()
Expected:
    Traceback (most recent call last):
    TypeError: not enough arguments for format string
Got:
    Traceback (most recent call last):
      File "<doctest strmethods.mod_format_tuple[1]>", line 1, in <module>
        mod_format_tuple()
        ~~~~~~~~~~~~~~~~^^
      File "tests/run/strmethods.pyx", line 160, in strmethods.mod_format_tuple
        return 'abc%sdef' % values
    TypeError: not enough arguments for format string (got 0)
======================================================================
FAIL: mod_format_tuple (strmethods) [1]
Doctest: strmethods.mod_format_tuple
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILD/Cython-3.2.4-build/cython-3.2.4/TEST_TMP/2/run/cpp/strmethods/strmethods.cpython-315-x86_64-linux-gnu.so", line 155, in strmethods.mod_format_tuple
AssertionError: Failed example:
    mod_format_tuple()
Expected:
    Traceback (most recent call last):
    TypeError: not enough arguments for format string
Got:
    Traceback (most recent call last):
      File "<doctest strmethods.mod_format_tuple[1]>", line 1, in <module>
        mod_format_tuple()
        ~~~~~~~~~~~~~~~~^^
      File "tests/run/strmethods.pyx", line 160, in strmethods.mod_format_tuple
        return 'abc%sdef' % values
    TypeError: not enough arguments for format string (got 0)
Errors from shard 9:
======================================================================
FAIL: test_formatting (test_unicode.UnicodeTest.test_formatting)
----------------------------------------------------------------------
TypeError: format argument: %x requires an integer, not float
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "tests/run/test_unicode.pyx", line 1449, in test_unicode.UnicodeTest.test_formatting
    self.assertRaisesRegex(TypeError, '%x format: an integer is required, not float', operator.mod, '%x', 3.14),
AssertionError: "%x format: an integer is required, not float" does not match "format argument: %x requires an integer, not float"
======================================================================
FAIL: test_formatting (test_unicode.UnicodeTest.test_formatting)
----------------------------------------------------------------------
TypeError: format argument: %x requires an integer, not float
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "tests/run/test_unicode.pyx", line 1449, in test_unicode.UnicodeTest.test_formatting
    self.assertRaisesRegex(TypeError, '%x format: an integer is required, not float', operator.mod, '%x', 3.14),
AssertionError: "%x format: an integer is required, not float" does not match "format argument: %x requires an integer, not float"

https://docs.python.org/3.15/whatsnew/3.15.html

For our attempts to build Cython with Python 3.15, see:
https://koji.fedoraproject.org/koji/search?terms=Cython&type=package&match=exact

Let us know here if you have any questions.

Python 3.15 is planned to be included in Fedora 45.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.15.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.

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