Add blog post about clang-20 availability

Author: resistor

_posts/2025-04-23-clang-20-in-devcontainer.markdown

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+---
+layout: post
+title:  "Clang 20 is now in the CHERIoT devcontainer!"
+date:   2025-04-23
+categories: cheri toolchain
+author: Owen Anderson
+---
+
+As of today, the [Clang 20](https://releases.llvm.org/20.1.0/tools/clang/docs/ReleaseNotes.html)/[LLVM 20](https://releases.llvm.org/20.1.0/docs/ReleaseNotes.html) toolchain is available in the CHERIoT devcontainer.
+This follows on the heels of our recent releases of [Clang 18](https://releases.llvm.org/18.1.0/tools/clang/docs/ReleaseNotes.html)/[LLVM 18](https://releases.llvm.org/18.1.0/docs/ReleaseNotes.html) and [Clang 19](https://releases.llvm.org/19.1.0/tools/clang/docs/ReleaseNotes.html)/[LLVM 19](https://releases.llvm.org/19.1.0/docs/ReleaseNotes.html) in recent months.
+
+With this release, we are now caught up to the most recent upstream Clang release.Going forward, we will be continuously tracking upstream Clang development in a `cheriot-upstream` branch within the [toolchain repository](https://github.com/cherIoT-Platform/llvm-project), and we will release new major versions to CHERIoT developers as they are released upstream as well.
+
+As we move beyond toolchain updates, we will be refocusing toolchain development on further enhancements, such as:
+
+* Adding support for [LLDB](https://lldb.llvm.org) as a debugger for CHERIoT hardware.
+* Implementing toolchain primitives needed to unblock [Rust](https://www.rust-lang.org) on CHERIoT, including burning down inline assembly [hacks](https://github.com/CHERIoT-Platform/llvm-project/issues/6).
+* Preparing the toolchain for ABI freeze, which will guarantee binary compatibility going forward.
+* Investigating performance and code size gaps compared to RISC-V.
+* User-requested bug fixes and improvements.
+
+As always, don't hesitate to report any issues or areas for improvement on the CHERIoT toolchain [issues page](https://github.com/CHERIoT-Platform/llvm-project/issues)!