Fix support for CPython development releases.

CHANGES.md

@@ -1,5 +1,16 @@
 # Release Notes
 
+## 2.32.1
+
+This release fixes a long-standing bug handling development versions of
+CPython (any non-tagged release of the interpreter). These interpreters
+report a full version of `X.Y.Z+` and the trailing `+` leads to a non
+PEP-440 compliant version number. This, in turn, causes issues with the
+`packaging` library leading to failures to evaluate markers for these
+interpreters which surface as inscrutable Pex errors.
+
+* Fix support for CPython development releases. (#2655)
+
 ## 2.32.0
 
 This release adds support for Pip 25.0.

pex/pep_508.py

@@ -15,6 +15,24 @@
     from pex.third_party import attr
 
 
+def _convert_non_pep_440_dev_versions(python_full_version):
+    # type: (Optional[str]) -> Optional[str]
+
+    # This applies the same workaround that exists in packaging as of its 24.1 release.
+    # See:
+    # + https://github.com/pypa/packaging/pull/802
+    # + https://github.com/pypa/packaging/pull/825
+    #
+    # N.B.: We can't simply upgrade to packaging >= 24.1 since those changes unconditionally access
+    # the `python_full_version` marker and our `AbbreviatedPlatform` can lead to marker environments
+    # without that marker filled in. Even if we could upgrade packaging though, that would only help
+    # Pex users on Python >= 3.8 whereas this fix applies to all Pex users.
+    if python_full_version and python_full_version.endswith("+"):
+        return python_full_version + "local"
+
+    return python_full_version
+
+
 @attr.s(frozen=True)
 class MarkerEnvironment(object):
     """A PEP-508 marker environment.
@@ -125,7 +143,9 @@ def from_platform(cls, platform):
     platform_release = attr.ib(default=None)  # type: Optional[str]
     platform_system = attr.ib(default=None)  # type: Optional[str]
     platform_version = attr.ib(default=None)  # type: Optional[str]
-    python_full_version = attr.ib(default=None)  # type: Optional[str]
+    python_full_version = attr.ib(
+        default=None, converter=_convert_non_pep_440_dev_versions
+    )  # type: Optional[str]
     python_version = attr.ib(default=None)  # type: Optional[str]
     sys_platform = attr.ib(default=None)  # type: Optional[str]
 

pex/version.py

@@ -1,4 +1,4 @@
 # Copyright 2015 Pex project contributors.
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
-__version__ = "2.32.0"
+__version__ = "2.32.1"

tests/test_pep_508.py

@@ -99,3 +99,11 @@ def assert_platform_machine(
 
     assert_platform_machine("x86_64", "macosx-10.15-x86_64-cp-38-m")
     assert_platform_machine("arm64", "macosx-11.0-arm64-cp-39-cp39")
+
+
+def test_cpython_dev_release():
+    env = MarkerEnvironment(python_full_version="3.10.16+").as_dict()
+    assert evaluate_marker("python_full_version >= '3.10.16'", env)
+    assert evaluate_marker("python_full_version <= '3.10.17'", env)
+    assert evaluate_marker("python_full_version == '3.10.16'", env)
+    assert not evaluate_marker("python_full_version === '3.10.16'", env)