No unreleased changes.

Features:

• PEP 751: support pylock (:pull:`900`)
• PEP 794: import name metadata (:pull:`948`)
• Support for writing metadata to a file (:pull:`846`)
• Support __replace__ on Version (:pull:`1003`)
• Support positional pattern matching for Version and SpecifierSet (:pull:`1004`)

Behavior adaptations:

• PEP 440 handling of prereleases for Specifier.contains, SpecifierSet.contains, and SpecifierSet.filter (:pull:`897`)
• Handle PEP 440 edge case in SpecifierSet.filter (:pull:`942`)
• Adjust arbitrary equality intersection preservation in SpecifierSet (:pull:`951`)
• Return False instead of raising for .contains with invalid version (:pull:`932`)
• Support arbitrary equality on arbitrary strings for Specifier and SpecifierSet's filter and contains method. (:pull:`954`)
• Only try to parse as Version on certain marker keys, return False on unequal ordered comparisons (:pull:`939`)

Fixes:

• Update _hash when unpickling Tag() (:pull:`860`)
• Correct comment and simplify implicit prerelease handling in Specifier.prereleases (:pull:`896`)
• Use explicit _GLibCVersion NamedTuple in _manylinux (:pull:`868`)
• Detect invalid license expressions containing () (:pull:`879`)
• Correct regex for metadata 'name' format (:pull:`925`)
• Improve the message around expecting a semicolon (:pull:`833`)
• Support nested parens in license expressions (:pull:`931`)
• Add space before at symbol in Requirements string (:pull:`953`)
• A root logger use found, use a packaging logger instead (:pull:`965`)
• Better support for subclassing Marker and Requirement (:pull:`1022`)
• Normalize all extras, not just if it comes first (:pull:`1024`)
• Don't produce a broken repr if Marker fails to construct (:pull:`1033`)

Performance:

• Avoid recompiling regexes in the tokenizer for a 3x speedup (:pull:`1019`)
• Improve performance in _manylinux.py (:pull:`869`)
• Minor cleanups to Version (:pull:`913`)
• Skip redundant creation of Version's in specifier comparison (:pull:`986`)
• Cache the Specifier's Version (:pull:`985`)
• Make Version a little faster (:pull:`987`)
• Minor Version regex cleanup (:pull:`990`)
• Faster regex on Python 3.11.5+ for Version (:pull:`988`, :pull:`1055`)
• Lazily calculate _key in Version (:pull:`989`, :pull:`1048`)
• Faster canonicalize_version (:pull:`993`)
• Use re.fullmatch in a couple more places (:pull:`992`, :pull:`1029`)
• Use map instead of generator (:pull:`996`)
• Deprecate ._version (_Version, a NamedTuple) (:pull:`995`, :pull:`1062`)
• Avoid duplicate Version creation in canonicalize_version (:pull:`994`)
• Add __slots__ to core classes (:pull:`1001`, :pull:`1002`, :pull:`1032`)
• Use Version.__replace__ in specifier comparison (:pull:`999`)
• Use _get_spec_version in more places in Specifier (:pull:`1005`)
• Pull set construction out of function (:pull:`1012`)
• Letter normalization dict for prereleases and the like (:pull:`1014`)
• Use str.partition in _parse_project_urls (:pull:`1013`)
• Avoid normalizing extras again when comparing (:pull:`1028`)
• Speed up Version.__str__ by about 10% (:pull:`997`)
• Much faster canonicalize_name by avoiding a regex (:pull:`1030`, :pull:`1047`, :pull:`1064`)
• Faster zero stripping (:pull:`1058`)

Type annotations:

• Fix a type annotation (:pull:`907`)
• Fix type hint of function used with contextlib.contextmanager (:pull:`1046`)
• Fix tags return type in parse_wheel_filename docs (:pull:`973`)
• Add type hint for _version in .version.Version (:pull:`927`)
• Changed static type annotations in prereleases setter method in specifier.py (:pull:`930`)
• Statically type our test suite (:pull:`982`)

Internal:

• Test and declare support for Python 3.14 (:pull:`901`)
• Change our license metadata to use an SPDX license expression (:pull:`881`, :pull:`924`)
• Expand the Ruff checks run on our codebase (:pull:`835`, :pull:`957`, :pull:`959`, :pull:`963`, :pull:`956`, :pull:`961`, :pull:`964`, :pull:`958`, :pull:`960`, :pull:`968`, :pull:`967`, :pull:`966`, :pull:`969`, :pull:`980`, :pull:`979`, :pull:`962`, :pull:`984`, :pull:`972`)
• Add spell checking (:pull:`904`, :pull:`910`, :pull:`1015`)
• Improve links back to source in the documentation (:pull:`991`)
• Add case insensitivity tests for arbitrary equality (:pull:`975`)
• Fix incorrectly implicitly concatenated string in specifiers test (:pull:`946`)
• Simpler else instead of assert in a check (:pull:`1027`, :pull:`1031`)
• Synchronize documentation and code for markers (:pull:`1008`)
• Use the GitHub Actions slim runner for the all pass check (:pull:`1021`)
• Use actionlint to check CI workflows (:pull:`1052`)
• Use Trusted Publishing (:pull:`893`, :pull:`1043`, :pull:`1045`, :pull:`1051`)
• Use zizmor to check CI (:pull:`1035`)
• Test on first public release of CPython 3.11 and newer (:pull:`1056`)

Since the final release candidate: Faster canonicalize_name, especially on Python 3.12 and 3.13, where performance regressed previously (:pull:`1064`), and reintroduce (deprecated) support for Version._.version (:pull:`1062`).

Third release candidate for 26.0. Avoid bug in CPython 3.11.0-3.11.4 and older PyPy 3.11 (:pull:`1055`).

Second release candidate for 26.0. Fixed a regression in (private) Version._key for packaging_legacy (:pull:`1048`), and speed up stripping zeros a little more (:pull:`1058`).

First release candidate for 26.0.

• PEP 751: Add support for extras and dependency_groups markers. (:issue:`885`)
• PEP 738: Add support for Android platform tags. (:issue:`880`)

• PEP 639: Implement License-Expression and License-File (:issue:`828`)
• Use !r formatter for error messages with filenames (:issue:`844`)
• Add support for PEP 730 iOS tags (:issue:`832`)
• Fix prerelease detection for > and < (:issue:`794`)
• Fix uninformative error message (:issue:`830`)
• Refactor canonicalize_version (:issue:`793`)
• Patch python_full_version unconditionally (:issue:`825`)
• Fix doc for canonicalize_version to mention strip_trailing_zero and a typo in a docstring (:issue:`801`)
• Fix typo in Version __str__ (:issue:`817`)
• Support creating a SpecifierSet from an iterable of Specifier objects (:issue:`775`)

• Document markers.default_environment() (:issue:`753`).
• Add support for Python 3.13 (:issue:`783`).
• Modernise type annotations (:issue:`785`).
• Work around platform.python_version() returning non PEP 440 compliant version for non-tagged CPython builds (:issue:`802`).

• Do specifier matching correctly when the specifier contains an epoch number and has more components than the version (:issue:`683`)
• Support the experimental --disable-gil builds in packaging.tags (:issue:`727`)
• BREAKING: Make optional metadata.Metadata attributes default to None (:issue:`733`)
• Fix errors when trying to access the description_content_type, keywords, and requires_python attributes on metadata.Metadata when those values have not been provided (:issue:`733`)
• Fix a bug preventing the use of the built in ExceptionGroup on versions of Python that support it (:issue:`725`)

• Document calendar-based versioning scheme (:issue:`716`)
• Enforce that the entire marker string is parsed (:issue:`687`)
• Requirement parsing no longer automatically validates the URL (:issue:`120`)
• Canonicalize names for requirements comparison (:issue:`644`)
• Introduce metadata.Metadata (along with metadata.ExceptionGroup and metadata.InvalidMetadata; :issue:`570`)
• Introduce the validate keyword parameter to utils.normalize_name() (:issue:`570`)
• Introduce utils.is_normalized_name() (:issue:`570`)
• Make utils.parse_sdist_filename() and utils.parse_wheel_filename() raise InvalidSdistFilename and InvalidWheelFilename, respectively, when the version component of the name is invalid
• Remove support for Python 3.7 (:issue:`783`)

• Parse raw metadata (:issue:`671`)
• Import underlying parser functions as an underscored variable (:issue:`663`)
• Improve error for local version label with unsupported operators (:issue:`675`)
• Add dedicated error for specifiers with incorrect .* suffix
• Replace spaces in platform names with underscores (:issue:`620`)
• Relax typing of _key on _BaseVersion (:issue:`669`)
• Handle prefix match with zeros at end of prefix correctly (:issue:`674`)

• Allow "extra" to be None in the marker environment (:issue:`650`)
• Refactor tags._generic_api to use EXT_SUFFIX (:issue:`607`)
• Correctly handle trailing whitespace on URL requirements (:issue:`642`)
• Fix typing for specifiers.BaseSpecifier.filter() (:issue:`643`)
• Use stable Python 3.11 in tests (:issue:`641`)
• Correctly handle non-normalised specifiers in requirements (:issue:`634`)
• Move to src/ layout (:issue:`626`)
• Remove __about__ file, in favour of keeping constants in __init__ (:issue:`626`)

• Explicitly declare support for Python 3.11 (:issue:`587`)
• Remove support for Python 3.6 (:issue:`500`)
• Remove LegacySpecifier and LegacyVersion (:issue:`407`)
• Add __hash__ and __eq__ to Requirement (:issue:`499`)
• Add a cpNNN-none-any tag (:issue:`541`)
• Adhere to PEP 685 when evaluating markers with extras (:issue:`545`)
• Allow accepting locally installed prereleases with SpecifierSet (:issue:`515`)
• Allow pre-release versions in marker evaluation (:issue:`523`)
• Correctly parse ELF for musllinux on Big Endian (:issue:`538`)
• Document packaging.utils.NormalizedName (:issue:`565`)
• Document exceptions raised by functions in packaging.utils (:issue:`544`)
• Fix compatible version specifier incorrectly strip trailing 0 (:issue:`493`)
• Fix macOS platform tags with old macOS SDK (:issue:`513`)
• Forbid prefix version matching on pre-release/post-release segments (:issue:`563`)
• Normalize specifier version for prefix matching (:issue:`561`)
• Improve documentation for packaging.specifiers and packaging.version. (:issue:`572`)
• Marker.evaluate will now assume evaluation environment with empty extra. Evaluating markers like "extra == 'xyz'" without passing any extra in the environment will no longer raise an exception (:issue:`550`)
• Remove dependency on pyparsing, by replacing it with a hand-written parser. This package now has no runtime dependencies (:issue:`468`)
• Update return type hint for Specifier.filter and SpecifierSet.filter to use Iterator instead of Iterable (:issue:`584`)

• Add a pp3-none-any tag (:issue:`311`)
• Replace the blank pyparsing 3 exclusion with a 3.0.5 exclusion (:issue:`481`, :issue:`486`)
• Fix a spelling mistake (:issue:`479`)

• Update documentation entry for 21.1.

• Update pin to pyparsing to exclude 3.0.0.

• PEP 656: musllinux support (:issue:`411`)
• Drop support for Python 2.7, Python 3.4 and Python 3.5.
• Replace distutils usage with sysconfig (:issue:`396`)
• Add support for zip files in parse_sdist_filename (:issue:`429`)
• Use cached _hash attribute to short-circuit tag equality comparisons (:issue:`417`)
• Specify the default value for the specifier argument to SpecifierSet (:issue:`437`)
• Proper keyword-only "warn" argument in packaging.tags (:issue:`403`)
• Correctly remove prerelease suffixes from ~= check (:issue:`366`)
• Fix type hints for Version.post and Version.dev (:issue:`393`)
• Use typing alias UnparsedVersion (:issue:`398`)
• Improve type inference for packaging.specifiers.filter() (:issue:`430`)
• Tighten the return type of canonicalize_version() (:issue:`402`)

• Run isort over the code base (:issue:`377`)
• Add support for the macosx_10_*_universal2 platform tags (:issue:`379`)
• Introduce packaging.utils.parse_wheel_filename() and parse_sdist_filename() (:issue:`387` and :issue:`389`)

• Revert back to setuptools for compatibility purposes for some Linux distros (:issue:`363`)
• Do not insert an underscore in wheel tags when the interpreter version number is more than 2 digits (:issue:`372`)

No unreleased changes.

• Fix flit configuration, to include LICENSE files (:issue:`357`)
• Make intel a recognized CPU architecture for the universal macOS platform tag (:issue:`361`)
• Add some missing type hints to packaging.requirements (issue:350)

• Officially support Python 3.9 (:issue:`343`)
• Deprecate the LegacyVersion and LegacySpecifier classes (:issue:`321`)
• Handle OSError on non-dynamic executables when attempting to resolve the glibc version string.

• Canonicalize version before comparing specifiers. (:issue:`282`)
• Change type hint for canonicalize_name to return packaging.utils.NormalizedName. This enables the use of static typing tools (like mypy) to detect mixing of normalized and un-normalized names.

• Fix changelog for 20.2.

• Fix a bug that caused a 32-bit OS that runs on a 64-bit ARM CPU (e.g. ARM-v8, aarch64), to report the wrong bitness.

• Fix a bug caused by reuse of an exhausted iterator. (:issue:`257`)

• Add type hints (:issue:`191`)
• Add proper trove classifiers for PyPy support (:issue:`198`)
• Scale back depending on ctypes for manylinux support detection (:issue:`171`)
• Use sys.implementation.name where appropriate for packaging.tags (:issue:`193`)
• Expand upon the API provided by packaging.tags: interpreter_name(), mac_platforms(), compatible_tags(), cpython_tags(), generic_tags() (:issue:`187`)
• Officially support Python 3.8 (:issue:`232`)
• Add major, minor, and micro aliases to packaging.version.Version (:issue:`225`)
• Properly mark packaging has being fully typed by adding a py.typed file (:issue:`226`)

• Remove dependency on attrs (:issue:`178`, :issue:`179`)
• Use appropriate fallbacks for CPython ABI tag (:issue:`181`, :issue:`185`)
• Add manylinux2014 support (:issue:`186`)
• Improve ABI detection (:issue:`181`)
• Properly handle debug wheels for Python 3.8 (:issue:`172`)
• Improve detection of debug builds on Windows (:issue:`194`)

• Add the packaging.tags module. (:issue:`156`)
• Correctly handle two-digit versions in python_version (:issue:`119`)

• Fix string representation of PEP 508 direct URL requirements with markers.

• Better handling of file URLs

  This allows for using file:///absolute/path, which was previously prevented due to the missing netloc.

  This allows for all file URLs that urlunparse turns back into the original URL to be valid.

• Improve error messages when invalid requirements are given. (:issue:`129`)

• Fix utils.canonicalize_version when supplying non PEP 440 versions.

• Drop support for python 2.6, 3.2, and 3.3.
• Define minimal pyparsing version to 2.0.2 (:issue:`91`).
• Add epoch, release, pre, dev, and post attributes to Version and LegacyVersion (:issue:`34`).
• Add Version().is_devrelease and LegacyVersion().is_devrelease to make it easy to determine if a release is a development release.
• Add utils.canonicalize_version to canonicalize version strings or Version instances (:issue:`121`).

• Fix markers that utilize in so that they render correctly.
• Fix an erroneous test on Python RC releases.

• Add support for the deprecated python_implementation marker which was an undocumented setuptools marker in addition to the newer markers.

• Add support for the deprecated, PEP 345 environment markers in addition to the newer markers.

• Fix a regression in parsing requirements with whitespaces between the comma separators.

• Fix a regression in parsing requirements like foo (==4).

• Fix a bug where packaging.requirements:Requirement was overly strict when matching legacy requirements.

• Add a function that implements the name canonicalization from PEP 503.

• Implement requirement specifiers from PEP 508.

• Relicense so that packaging is available under either the Apache License, Version 2.0 or a 2 Clause BSD license.
• Support installation of packaging when only distutils is available.
• Fix == comparison when there is a prefix and a local version in play. (:issue:`41`).
• Implement environment markers from PEP 508.

• Normalize post-release spellings for rev/r prefixes. :issue:`35`

• Fix an error where the arbitrary specifier (===) was not correctly allowing pre-releases when it was being used.
• Expose the specifier and version parts through properties on the Specifier classes.
• Allow iterating over the SpecifierSet to get access to all of the Specifier instances.
• Allow testing if a version is contained within a specifier via the in operator.

• Fix a logic error that was causing inconsistent answers about whether or not a pre-release was contained within a SpecifierSet or not.

• Add Version().is_postrelease and LegacyVersion().is_postrelease to make it easy to determine if a release is a post release.
• Add Version().base_version and LegacyVersion().base_version to make it easy to get the public version without any pre or post release markers.
• Support the update to PEP 440 which removed the implied !=V.* when using either >V or <V and which instead special cased the handling of pre-releases, post-releases, and local versions when using >V or <V.

• Normalize release candidates as rc instead of c.
• Expose the VERSION_PATTERN constant, a regular expression matching a valid version.

• Ensure that versions are normalized before comparison when used in a specifier with a less than (<) or greater than (>) operator.

• BACKWARDS INCOMPATIBLE Refactor specifier support so that it can sanely handle legacy specifiers as well as PEP 440 specifiers.
• BACKWARDS INCOMPATIBLE Move the specifier support out of packaging.version into packaging.specifiers.

• Add prerelease support to Specifier.
• Remove the ability to do item in Specifier() and replace it with Specifier().contains(item) in order to allow flags that signal if a prerelease should be accepted or not.
• Add a method Specifier().filter() which will take an iterable and returns an iterable with items that do not match the specifier filtered out.

• Allow LegacyVersion and Version to be sorted together.
• Add packaging.version.parse() to enable easily parsing a version string as either a Version or a LegacyVersion depending on it's PEP 440 validity.

• Initial release.