Latest setuptools and flit now support PEP 639

This updates the now outdated notes added in
faf4c7d.

Closes #1831.

Author: not-my-profile

source/guides/licensing-examples-and-user-scenarios.rst

@@ -12,8 +12,6 @@ This document aims to provide clear guidance how to migrate from the legacy
 to the standardized way of declaring licenses.
 Make sure your preferred build backend supports :pep:`639` before
 trying to apply the newer guidelines.
-As of February 2025, :doc:`setuptools <setuptools:userguide/pyproject_config>`
-and :ref:`flit <flit:pyproject_toml_project>` don't support :pep:`639` yet.
 
 
 Licensing Examples

source/guides/writing-pyproject-toml.rst

@@ -291,22 +291,43 @@ You can also specify the format explicitly, like this:
    readme = {file = "README.txt", content-type = "text/x-rst"}
 
 
-.. _license:
+.. _license-and-license-files:
 
-``license``
------------
+``license`` and ``license-files``
+---------------------------------
+
+As per :pep:`639` licenses should be declared with two fields:
+
+- ``license`` is an :term:`SPDX license expression <License Expression>` consisting
+  of one or more :term:`license identifiers <License Identifier>`.
+- ``license-files`` is a list of license file glob patterns.
+
+A previous PEP had specified ``license`` to be a table with a ``file`` or a
+``text`` key, this format is now deprecated. Most :term:`build backends<build
+backend>` now support the new format as shown in the following table.
+
+.. list-table:: build backend versions that introduced :pep:`639` support
+   :header-rows: 1
 
-:pep:`639` (accepted in August 2024) has changed the way the ``license`` field
-is declared. Make sure your preferred build backend supports :pep:`639` before
-trying to apply the newer guidelines.
-As of February 2025, :doc:`setuptools <setuptools:userguide/pyproject_config>`
-and :ref:`flit <flit:pyproject_toml_project>` don't support :pep:`639` yet.
+   * - hatchling
+     - setuptools
+     - flit-core [#flit-core-pep639]_
+     - pdm-backend
+     - poetry-core
+   * - 1.27.0
+     - 77.0.3
+     - 3.12
+     - 2.4.0
+     - `not yet <poetry-pep639-issue_>`_
 
-:pep:`639` license declaration
-''''''''''''''''''''''''''''''
 
-This is a valid :term:`SPDX license expression <License Expression>` consisting
-of one or more :term:`license identifiers <License Identifier>`.
+.. _license:
+
+``license``
+'''''''''''
+
+The new format for ``license`` is a valid :term:`SPDX license expression <License Expression>`
+consisting of one or more :term:`license identifiers <License Identifier>`.
 The full license list is available at the
 `SPDX license list page <spdxlicenselist_>`_. The supported list version is
 3.17 or any later compatible one.
@@ -318,6 +339,11 @@ The full license list is available at the
     # or
     license = "MIT AND (Apache-2.0 OR BSD-2-Clause)"
 
+.. note:: If you get a build error that ``license`` should be a dict/table,
+   your build backend doesn't yet support the new format. See the
+   `above section <license-and-license-files_>`_ for more context.
+   The now deprecated format is `described in PEP 621 <https://peps.python.org/pep-0621/#license>`__.
+
 As a general rule, it is a good idea to use a standard, well-known
 license, both to avoid confusion and because some organizations avoid software
 whose license is unapproved.
@@ -332,41 +358,11 @@ The custom identifiers must follow the SPDX specification,
     [project]
     license = "LicenseRef-My-Custom-License"
 
-Legacy license declaration
-''''''''''''''''''''''''''
-
-This can take two forms. You can put your license in a file, typically
-:file:`LICENSE` or :file:`LICENSE.txt`, and link that file here:
-
-.. code-block:: toml
-
-    [project]
-    license = {file = "LICENSE"}
-
-or you can write the name of the license:
-
-.. code-block:: toml
-
-    [project]
-    license = {text = "MIT License"}
-
-If you are using a standard, well-known license, it is not necessary to use this
-field. Instead, you should use one of the :ref:`classifiers` starting with ``License
-::``. (As a general rule, it is a good idea to use a standard, well-known
-license, both to avoid confusion and because some organizations avoid software
-whose license is unapproved.)
-
 
 .. _license-files:
 
 ``license-files``
------------------
-
-:pep:`639` (accepted in August 2024) has introduced the ``license-files`` field.
-Make sure your preferred build backend supports :pep:`639` before declaring the
-field.
-As of February 2025, :doc:`setuptools <setuptools:userguide/pyproject_config>`
-and :ref:`flit <flit:pyproject_toml_project>` don't support :pep:`639` yet.
+'''''''''''''''''
 
 This is a list of license files and files containing other legal
 information you want to distribute with your package.
@@ -541,7 +537,7 @@ A full example
    ]
    description = "Lovely Spam! Wonderful Spam!"
    readme = "README.rst"
-   license = "MIT"  # or license = {file = "LICENSE.txt"} for legacy declaration
+   license = "MIT"
    license-files = ["LICEN[CS]E.*"]
    keywords = ["egg", "bacon", "sausage", "tomatoes", "Lobster Thermidor"]
    classifiers = [
@@ -579,13 +575,17 @@ A full example
    like ``requires-python = "<= 3.10"`` here. `This blog post <requires-python-blog-post_>`_
    contains some information regarding possible problems.
 
+.. [#flit-core-pep639] flit-core `does not yet <flit-issue-735_>`_ support WITH in SPDX license expressions.
+
+.. _flit-issue-735: https://github.com/pypa/flit/issues/735
 .. _gfm: https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax
 .. _setuptools: https://setuptools.pypa.io
 .. _poetry: https://python-poetry.org
 .. _pypi-pip: https://pypi.org/project/pip
 .. _pypi-search-pip: https://pypi.org/search?q=pip
 .. _classifier-list: https://pypi.org/classifiers
 .. _requires-python-blog-post: https://iscinumpy.dev/post/bound-version-constraints/#pinning-the-python-version-is-special
+.. _poetry-pep639-issue: https://github.com/python-poetry/poetry/issues/9670
 .. _pytest: https://pytest.org
 .. _pygments: https://pygments.org
 .. _rest: https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html

source/shared/build-backend-tabs.rst

@@ -1,33 +1,34 @@
 .. (comment) This file is included in guides/writing-pyproject-toml.rst and tutorials/packaging-projects.rst.
+.. The minimum versions here are the versions that introduced support for PEP 639.
 
 .. tab:: Hatchling
 
     .. code-block:: toml
 
         [build-system]
-        requires = ["hatchling"]
+        requires = ["hatchling >= 1.26"]
         build-backend = "hatchling.build"
 
 .. tab:: setuptools
 
     .. code-block:: toml
 
         [build-system]
-        requires = ["setuptools >= 61.0"]
+        requires = ["setuptools >= 77.0.3"]
         build-backend = "setuptools.build_meta"
 
 .. tab:: Flit
 
     .. code-block:: toml
 
         [build-system]
-        requires = ["flit_core >= 3.4"]
+        requires = ["flit_core >= 3.12.0"]
         build-backend = "flit_core.buildapi"
 
 .. tab:: PDM
 
     .. code-block:: toml
 
         [build-system]
-        requires = ["pdm-backend"]
+        requires = ["pdm-backend >= 2.4.0"]
         build-backend = "pdm.backend"

source/tutorials/packaging-projects.rst

@@ -144,6 +144,8 @@ Frontends usually run builds in isolated environments, so omitting dependencies
 here may cause build-time errors.
 This should always include your backend's package, and might have other build-time
 dependencies.
+The minimum version specified in the above code block is the one that introduced support
+for :ref:`the new license metadata <license-and-license-files>`.
 
 The ``build-backend`` key is the name of the Python object that frontends will use
 to perform the build.
@@ -169,52 +171,27 @@ to include your username; this ensures that you have a unique
 package name that doesn't conflict with packages uploaded by other people
 following this tutorial.
 
-.. tab:: hatchling/pdm
-
-  .. code-block:: toml
-
-      [project]
-      name = "example_package_YOUR_USERNAME_HERE"
-      version = "0.0.1"
-      authors = [
-        { name="Example Author", email="[email protected]" },
-      ]
-      description = "A small example package"
-      readme = "README.md"
-      requires-python = ">=3.8"
-      classifiers = [
-          "Programming Language :: Python :: 3",
-          "Operating System :: OS Independent",
-      ]
-      license = "MIT"
-      license-files = ["LICEN[CS]E*"]
-
-      [project.urls]
-      Homepage = "https://github.com/pypa/sampleproject"
-      Issues = "https://github.com/pypa/sampleproject/issues"
-
-.. tab:: setuptools/flit
-
-  .. code-block:: toml
-
-      [project]
-      name = "example_package_YOUR_USERNAME_HERE"
-      version = "0.0.1"
-      authors = [
-        { name="Example Author", email="[email protected]" },
-      ]
-      description = "A small example package"
-      readme = "README.md"
-      requires-python = ">=3.8"
-      classifiers = [
-          "Programming Language :: Python :: 3",
-          "Operating System :: OS Independent",
-          "License :: OSI Approved :: MIT License",
-      ]
-
-      [project.urls]
-      Homepage = "https://github.com/pypa/sampleproject"
-      Issues = "https://github.com/pypa/sampleproject/issues"
+.. code-block:: toml
+
+    [project]
+    name = "example_package_YOUR_USERNAME_HERE"
+    version = "0.0.1"
+    authors = [
+      { name="Example Author", email="[email protected]" },
+    ]
+    description = "A small example package"
+    readme = "README.md"
+    requires-python = ">=3.8"
+    classifiers = [
+        "Programming Language :: Python :: 3",
+        "Operating System :: OS Independent",
+    ]
+    license = "MIT"
+    license-files = ["LICEN[CS]E*"]
+
+    [project.urls]
+    Homepage = "https://github.com/pypa/sampleproject"
+    Issues = "https://github.com/pypa/sampleproject/issues"
 
 - ``name`` is the *distribution name* of your package. This can be any name as
   long as it only contains letters, numbers, ``.``, ``_`` , and ``-``. It also
@@ -243,10 +220,9 @@ following this tutorial.
   your package will work on. For a complete list of classifiers, see
   https://pypi.org/classifiers/.
 - ``license`` is the :term:`SPDX license expression <License Expression>` of
-  your package. Not supported by all the build backends yet.
+  your package.
 - ``license-files`` is the list of glob paths to the license files,
   relative to the directory where :file:`pyproject.toml` is located.
-  Not supported by all the build backends yet.
 - ``urls`` lets you list any number of extra links to show on PyPI.
   Generally this could be to the source, documentation, issue trackers, etc.