Bumping Minimum MacOS version to 10.13

#1993

Co-authored-by: Matthew R. Becker <[email protected]>
Co-authored-by: h-vetinari <[email protected]>

Author: 3 people

news/2023-08-24-bumping-minimum-macos-version-to-1013.md

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+# 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.