diff --git a/source/specifications/core-metadata.rst b/source/specifications/core-metadata.rst index 0cd05f9fa..b6fd009e2 100644 --- a/source/specifications/core-metadata.rst +++ b/source/specifications/core-metadata.rst @@ -6,7 +6,7 @@ Core metadata specifications ============================ -This page describes version 2.5, approved in September 2025. +This page describes version 2.6, approved in May 2026. Fields defined in the following specification should be considered valid, complete and not subject to change. The required fields are: @@ -50,7 +50,7 @@ Metadata-Version .. versionadded:: 1.0 Version of the file format; legal values are "1.0", "1.1", "1.2", "2.1", -"2.2", "2.3", "2.4", and "2.5". +"2.2", "2.3", "2.4", "2.5", and "2.6". Automated tools consuming metadata SHOULD warn if ``metadata-version`` is greater than the highest version they support, and MUST fail if @@ -109,6 +109,10 @@ Dynamic (multiple use) ====================== .. versionadded:: 2.2 +.. versionchanged:: 2.6 + A multiple use field that is present in the sdist and also marked + ``Dynamic`` may only be appended to in a wheel built from the sdist. + Previously any field listed in Dynamic was ignored in an sdist. A string containing the name of another core metadata field. The field names ``Name``, ``Version``, and ``Metadata-Version`` may not be specified @@ -121,8 +125,12 @@ rules apply: in any wheel built from the sdist MUST match the value in the sdist. If the field is not in the sdist, and not marked as ``Dynamic``, then it MUST NOT be present in the wheel. -2. If a field is marked as ``Dynamic``, it may contain any valid value in - a wheel built from the sdist (including not being present at all). +2. If a single-use field is marked as ``Dynamic``, it may contain any valid + value in a wheel built from the sdist (including not being present at all). +3. If a multiple use field is present in the sdist and also marked ``Dynamic``, + then a wheel built from the sdist MUST include the value(s) present in the + sdist. The wheel MAY add further values, but it MUST NOT remove, reorder, or + modify the values present in the sdist. If the sdist metadata version is older than version 2.2, then all fields should be treated as if they were specified with ``Dynamic`` (i.e. there are no special @@ -1074,6 +1082,12 @@ History - January 2026: Replaced outdated direct reference to :pep:`508` with a reference to :ref:`dependency-specifiers`. +- May 2026: Core metadata 2.6 was approved through :pep:`808`. + + - Allowed a multiple use field marked ``Dynamic`` to be appended to in a + wheel built from a sdist, requiring the wheel to preserve the value(s) + present in the sdist. + ---- .. [1] reStructuredText markup: diff --git a/source/specifications/pyproject-toml.rst b/source/specifications/pyproject-toml.rst index 60c7218f9..2708b02ac 100644 --- a/source/specifications/pyproject-toml.rst +++ b/source/specifications/pyproject-toml.rst @@ -114,6 +114,13 @@ by the metadata). Dynamic metadata is listed via the ``dynamic`` key (defined later in this specification) and represents metadata that a tool will later provide. +A key whose value is a list or a table of arbitrary entries MAY be +specified statically *and* listed in ``dynamic`` at the same time. In +that case the entries given statically are fixed and a build back-end +MAY only *append* further entries to them; the back-end MUST NOT +remove, reorder, or modify any statically-specified entries. See the +:ref:`dynamic ` key for details. + The lack of a ``[project]`` table implicitly means the :term:`build backend ` will dynamically provide all keys. @@ -619,8 +626,9 @@ provided via tooling later on. field as "Optional", the metadata MAY list it in ``dynamic`` if the expectation is a build back-end will provide the data for the key later. -- Build back-ends MUST raise an error if the metadata specifies a - key statically as well as being listed in ``dynamic``. +- Build back-ends MUST raise an error if the metadata specifies a key + statically as well as being listed in ``dynamic``, *unless* the key + represents a list or arbitrary table that can be extended, listed below. - If the metadata does not list a key in ``dynamic``, then a build back-end CANNOT fill in the requisite metadata on behalf of the user (i.e. ``dynamic`` is the only way to allow a tool to fill in @@ -630,6 +638,35 @@ provided via tooling later on. the data for it (omitting the data, if determined to be the accurate value, is acceptable). +A key whose value is a list or a table of arbitrary entries MAY be +specified statically and listed in ``dynamic`` simultaneously. The +keys fitting that description are: + +- ``authors`` +- ``classifiers`` +- ``dependencies`` +- ``entry-points`` +- ``gui-scripts`` +- ``import-names`` +- ``import-namespaces`` +- ``keywords`` +- ``license-files`` +- ``maintainers`` +- ``optional-dependencies`` +- ``scripts`` +- ``urls`` + +When such a key is specified both statically and listed in +``dynamic``: + +- A build back-end MAY only *append* entries to the value; it MUST NOT + remove, reorder, or modify any statically-specified entries. For + tables (such as ``optional-dependencies`` or ``entry-points``) this + means a back-end MAY add new keys and MAY append to the values of + existing keys (in the case of a list), but MUST NOT change or remove the + entries given statically. +- A build back-end SHOULD raise an error if a key is listed in + ``dynamic`` and it does not support extending that key. .. _pyproject-tool-table: @@ -673,4 +710,8 @@ History - January 2026: Replaced outdated direct reference to :pep:`508` with a reference to :ref:`dependency-specifiers`. +- May 2026: Allowed list and table keys to be specified statically as well + as listed in ``dynamic``, with build back-ends only able to append + entries, through :pep:`808`. + .. _TOML: https://toml.io