Merge pull request matplotlib#21527 from QuLogic/more-3.5-docs

Add more 3.5 release notes

Author: QuLogic

doc/api/prev_api_changes/api_changes_3.5.0/development.rst

@@ -18,6 +18,39 @@ some :ref:`optional dependencies <optional_dependencies>` are being bumped:
 This is consistent with our :ref:`min_deps_policy` and `NEP29
 <https://numpy.org/neps/nep-0029-deprecation_policy.html>`__
 
+New wheel architectures
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Wheels have been added for:
+
+- Python 3.10
+- PyPy 3.7
+- macOS on Apple Silicon (both arm64 and universal2)
+
+New build dependencies
+~~~~~~~~~~~~~~~~~~~~~~
+
+Versioning has been switched from bundled versioneer to `setuptools-scm
+<https://github.com/pypa/setuptools_scm/>`__ using the
+``release-branch-semver`` version scheme. The latter is well-maintained, but
+may require slight modification to packaging scripts.
+
+The `setuptools-scm-git-archive
+<https://pypi.org/project/setuptools-scm-git-archive/>`__ plugin is also used
+for consistent version export.
+
+Data directory is no longer optional
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Historically, the ``mpl-data`` directory has been optional (example files were
+unnecessary, and fonts could be deleted if a suitable dependency on a system
+font were provided). Though example files are still optional, they have been
+substantially pared down, and we now consider the directory to be required.
+
+Specifically, the ``matplotlibrc`` file found there is used for runtime
+verifications and must exist. Packagers may still symlink fonts to system
+versions if needed.
+
 New runtime dependencies
 ~~~~~~~~~~~~~~~~~~~~~~~~
 

doc/users/explain/backends.rst

@@ -232,19 +232,23 @@ for more details.
 
 .. _QT_API-usage:
 
-How do I select PyQt5 or PySide2?
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+How do I select the Qt implementation?
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-The :envvar:`QT_API` environment variable can be set to either ``pyqt5`` or
-``pyside2`` to use ``PyQt5`` or ``PySide2``, respectively.
+The QtAgg and QtCairo backends support both Qt 5 and 6, as well as both Python
+bindings (`PyQt`_ or `Qt for Python`_, a.k.a. PySide). If any binding has
+already been loaded, then it will be used for the Qt backend. Otherwise, the
+first available binding is used, in the order: PyQt6, PySide6, PyQt5, PySide2.
 
-Since the default value for the bindings to be used is ``PyQt5``, Matplotlib
-first tries to import it. If the import fails, it tries to import
-``PySide2``.
+The :envvar:`QT_API` environment variable can be set to override the search
+when nothing has already been loaded. It may be set to (case-insensitively)
+PyQt6, PySide6, PyQt5, or PySide2 to pick the version and binding to use. If
+the chosen implementation is unavailable, the Qt backend will fail to load
+without attempting any other Qt implementations.
 
 Using non-builtin backends
 --------------------------
 More generally, any importable backend can be selected by using any of the
 methods above. If ``name.of.the.backend`` is the module containing the
 backend, use ``module://name.of.the.backend`` as the backend name, e.g.
-``matplotlib.use('module://name.of.the.backend')``.
+``matplotlib.use('module://name.of.the.backend')``.