Meta: Switch to clang-format-20 as the standard formatter

Author: https://github.com/trflynn89
Commit: d30f6f1b11
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4715
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/BertalanD
Reviewed-by: https://github.com/InvalidUsernameException

.github/workflows/lint-code.yml

@@ -15,7 +15,7 @@ jobs:
         run: |
           set -e
 
-          brew install curl flake8 llvm@19 ninja optipng shellcheck swift-format unzip
+          brew install curl flake8 llvm@20 ninja optipng shellcheck swift-format unzip
 
           # Note: gn isn't available in homebrew :(
           # Corresponds to https://gn.googlesource.com/gn/+/225e90c5025bf74f41dbee60d9cde4512c846fe7

CONTRIBUTING.md

@@ -67,7 +67,7 @@ Nobody is perfect, and sometimes we mess things up. That said, here are some goo
 **Do:**
 
 * Write in idiomatic project-style C++23, using the `AK` containers in all code.
-* Conform to the project coding style found in [CodingStyle.md](https://github.com/LadybirdBrowser/ladybird/blob/master/Documentation/CodingStyle.md). Use `clang-format` (version 19) to automatically format C++ files. See [AdvancedBuildInstructions.md](https://github.com/LadybirdBrowser/ladybird/blob/master/Documentation/AdvancedBuildInstructions.md#clang-format-updates) for instructions on how to get an up-to-date version if your OS distribution does not ship clang-format-19.
+* Conform to the project coding style found in [CodingStyle.md](https://github.com/LadybirdBrowser/ladybird/blob/master/Documentation/CodingStyle.md). Use `clang-format` to automatically format C++ files.
 * Choose expressive variable, function and class names. Make it as obvious as possible what the code is doing.
 * Split your changes into separate, atomic commits (i.e. A commit per feature or fix, where the build, tests and the system are all functioning).
 * Make sure your commits are rebased on the master branch.

Documentation/CodingStyle.md

@@ -2,7 +2,12 @@
 
 For low-level styling (spaces, parentheses, brace placement, etc), all code should follow the format specified in `.clang-format` in the project root.
 
-**Important: Make sure you use `clang-format` version 19!**
+**Important: Make sure you use the correct version of `clang-format`!**
+
+See [lint-clang-format.sh](../Meta/lint-clang-format.sh) for the version enforced in CI.
+
+See [AdvancedBuildInstructions.md](AdvancedBuildInstructions.md#clang-format-updates) for instructions on how to get an
+up-to-date version if your OS distribution does not ship the correct version.
 
 This document describes the coding style used for C++ code in the Ladybird Browser project. All new code should conform to this style.
 

Meta/lint-clang-format.sh

@@ -2,7 +2,7 @@
 
 set -e
 
-CLANG_FORMAT_VERSION=19
+CLANG_FORMAT_VERSION=20
 
 script_path=$(cd -P -- "$(dirname -- "$0")" && pwd -P)
 cd "${script_path}/.." || exit 1