docs: update changelog and versionadded

CONTRIBUTING.md

@@ -60,7 +60,7 @@ system with CMake 3.14+:
 python3 -m venv venv
 source venv/bin/activate
 pip install -r tests/requirements.txt
-cmake -S . -B build -DPYTHON_EXECUTABLE=$(which python) -DDOWNLOAD_CATCH=ON -DDOWNLOAD_EIGEN=ON
+cmake -S . -B build -DDOWNLOAD_CATCH=ON -DDOWNLOAD_EIGEN=ON
 cmake --build build -j4
 ```
 
@@ -71,9 +71,10 @@ Tips:
 * You can select any name for your environment folder; if it contains "env" it
   will be ignored by git.
 * If you don’t have CMake 3.14+, just add “cmake” to the pip install command.
-* You can use `-DPYBIND11_FINDPYTHON=ON` instead of setting the
-  `PYTHON_EXECUTABLE` - the new search algorithm can find virtual environments,
-  Conda, and more.
+* You can use `-DPYBIND11_FINDPYTHON=ON` to use FindPython on CMake 3.12+
+* In classic mode, you may need to set `-DPYTHON_EXECUTABLE=/path/to/python`.
+  FindPython uses `-DPython_ROOT_DIR=/path/to` or
+  `-DPython_EXECUTABLE=/path/to/python`.
 
 ### Configuration options
 
@@ -104,10 +105,12 @@ The valid options are:
 * Use `cmake build -LH` to list the CMake options with help.
 * Use `ccmake` if available to see a curses (terminal) gui, or `cmake-gui` for
   a completely graphical interface (not present in the PyPI package).
-* Use `-G` and the name of a generator to use something different, like `Ninja`
-  (automatic multithreading!). `cmake --help` lists the generators available.
-* Open the `CMakeLists.txt` with QtCreator to generate for that IDE.
 * Use `cmake --build build -j12` to build with 12 cores (for example).
+* Use `-G` and the name of a generator to use something different. `cmake
+  --help` lists the generators available.
+      - On Unix, setting `CMAKE_GENERATER=Ninja` in your environment will give
+        you automatic mulithreading on all your CMake projects!
+* Open the `CMakeLists.txt` with QtCreator to generate for that IDE.
 * You can use `-DCMAKE_EXPORT_COMPILE_COMMANDS=ON` to generate the `.json` file
   that some tools expect.
 

docs/advanced/classes.rst

@@ -149,8 +149,7 @@ memory for the C++ portion of the instance will be left uninitialized, which
 will generally leave the C++ instance in an invalid state and cause undefined
 behavior if the C++ instance is subsequently used.
 
-.. versionadded:: 2.5.1
-
+.. versionchanged:: 2.6
    The default pybind11 metaclass will throw a ``TypeError`` when it detects
    that ``__init__`` was not called by a derived class.
 
@@ -597,6 +596,8 @@ For more information, see :ref:`the documentation on exceptions <unraisable_exce
 
     pybind11 does not support C++ destructors marked ``noexcept(false)``.
 
+.. versionadded:: 2.6
+
 .. _implicit_conversions:
 
 Implicit conversions
@@ -1147,6 +1148,8 @@ error:
 
 .. note:: This attribute is currently ignored on PyPy
 
+.. versionadded:: 2.6
+
 Custom automatic downcasters
 ============================
 

docs/advanced/exceptions.rst

@@ -188,3 +188,5 @@ You can convert them to Python exceptions and then discard as unraisable.
             third_party::log(e);
         }
     }
+
+.. versionadded:: 2.6

docs/advanced/functions.rst

@@ -390,6 +390,8 @@ argument annotations when registering the function:
 Note that, as in Python, you cannot combine this with a ``py::args`` argument.
 This feature does *not* require Python 3 to work.
 
+.. versionadded:: 2.6
+
 .. _nonconverting_arguments:
 
 Non-converting arguments

docs/advanced/pycpp/numpy.rst

@@ -387,6 +387,9 @@ operation on the C++ side:
    py::array a = /* A NumPy array */;
    py::array b = a[py::make_tuple(0, py::ellipsis(), 0)];
 
+.. versionchanged:: 2.6
+   ``py::ellipsis()`` is now also avaliable in Python 2.
+
 Memory view
 ===========
 
@@ -428,3 +431,6 @@ We can also use ``memoryview::from_memory`` for a simple 1D contiguous buffer:
 .. note::
 
     ``memoryview::from_memory`` is not available in Python 2.
+
+.. versionchanged:: 2.6
+    ``memoryview::from_memory`` added.

docs/changelog.rst

@@ -11,6 +11,24 @@ v2.6.0 (IN PROGRESS)
 
 See :ref:`upgrade-guide-2.6` for help upgrading to the new version.
 
+* Keyword only argument supported in Python 2 or 3 with ``py::kwonly()``.
+  `#2100 <https://github.com/pybind/pybind11/pull/2100>`_
+
+* Perfect forwarding support for methods.
+  `#2048 <https://github.com/pybind/pybind11/pull/2048>`_
+
+* Added ``py::error_already_set::discard_as_unraisable()``.
+  `#2372 <https://github.com/pybind/pybind11/pull/2372>`_
+
+* ``py::hash`` is now public.
+  `#2217 <https://github.com/pybind/pybind11/pull/2217>`_
+
+* ``py::is_final()`` class modifier to block subclassing (CPython only).
+  `#2151 <https://github.com/pybind/pybind11/pull/2151>`_
+
+* ``py::memoryview``  update and documentation.
+  `#2223 <https://github.com/pybind/pybind11/pull/2223>`_
+
 * Minimum CMake required increased to 3.4.
   `#2338 <https://github.com/pybind/pybind11/pull/2338>`_ and
   `#2370 <https://github.com/pybind/pybind11/pull/2370>`_
@@ -36,6 +54,39 @@ See :ref:`upgrade-guide-2.6` for help upgrading to the new version.
   `#2265 <https://github.com/pybind/pybind11/pull/2265>`_ and
   `#2346 <https://github.com/pybind/pybind11/pull/2346>`_
 
+Smaller or developer focused features:
+
+* Error now thrown when ``__init__`` is forgotten on subclasses.
+  `#2152 <https://github.com/pybind/pybind11/pull/2152>`_
+
+* If ``__eq__`` defined but not ``__hash__``, ``__hash__`` is now set to
+  ``None``.
+  `#2291 <https://github.com/pybind/pybind11/pull/2291>`_
+
+* ``py::ellipsis`` now also works on Python 2
+  `#2360 <https://github.com/pybind/pybind11/pull/2360>`_
+
+* Added missing signature for ``py::array``
+  `#2363 <https://github.com/pybind/pybind11/pull/2363>`_
+
+* Bugfixes related to more extensive testing
+  `#2321 <https://github.com/pybind/pybind11/pull/2321>`_
+
+* Pointer to ``std::tuple`` & ``std::pair`` supported in cast.
+  `#2334 <https://github.com/pybind/pybind11/pull/2334>`_
+
+* Small fixes in NumPy support. ``py::array`` now uses ``py::ssize_t`` as first
+  argument type.
+  `#2293 <https://github.com/pybind/pybind11/pull/2293>`_
+
+* PyPy fixes, including support for PyPy3 and PyPy 7.
+  `#2146 <https://github.com/pybind/pybind11/pull/2146>`_
+
+* CPython 3.9 fixes.
+  `#2253 <https://github.com/pybind/pybind11/pull/2253>`_
+
+* Debug Python interpreter support.
+  `#2025 <https://github.com/pybind/pybind11/pull/2025>`_
 
 
 

docs/upgrade.rst

@@ -13,6 +13,14 @@ modernization and other useful information.
 v2.6
 ====
 
+An error is now thrown when ``__init__`` is forgotten on subclasses. This was
+incorrect before, but was not checked. Add a call to ``__init__`` if it is
+missing.
+
+If ``__eq__`` defined but not ``__hash__``, ``__hash__`` is now set to
+``None``, as in normal CPython. You should add ``__hash__`` if you intended the
+class to be hashable, possibly using the new ``py::hash`` shortcut.
+
 CMake support:
 --------------