Merge pull request #1993 from h-vetinari/macos

add announcement for dropping MacOS<10.13

src/user/announcements.rst

@@ -8,6 +8,24 @@ Our announcements are published to an RSS feed `here <https://conda-forge.org/do
 2023
 ----
 
+2023-08-24: Bumping Minimum MacOS version to 10.13
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+We will bump the minimum MacOS version from 10.9 (released in Oct. 2013, end-of-life since
+Dec. 2016) to 10.13 (released Sept. 2017, end-of-life since Dec. 2020). The main reason we
+managed to support 10.9 this long at all, is that conda-forge is able to ship an up-to-date
+C++ standard library for OSX, ``libcxx``, superseding the old one present in the MacOS SDK
+on the system (at least from the point-of-view of the respective conda environments).
+
+However, several core packages in the ecosystem now require at least 10.13 (or will very soon),
+in a way that we cannot be circumvent. These packages include ``libcxx``,
+`starting <https://discourse.llvm.org/t/libc-bumping-minimal-deployment-target-for-building-the-dylib-static-library-on-macos/68912>`_
+with version 17.0.
+This change will not affect already published artifacts, but in the near future, all new builds
+for OSX will require at least 10.13. This constraint will be implemented through the ``__osx``
+virtual package, but the details of how we will achieve this are still being worked out. Only ``conda`` versions 4.8.0 or newer have this virtual package. If you are using a system with MacOS older than 10.13 and are using ``conda`` older than 4.8.0, you will need to either upgrade ``conda`` to at least 4.8.0 or upgrade your system to at least MacOS 10.13.
+
+
 2023-07-12: End-of-life for CentOS 6
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^