Use clang-format 20

Author: st0012

.github/workflows/clang-format.yml

@@ -33,8 +33,11 @@ jobs:
           sudo apt-get install -y libdb-dev curl autoconf automake m4 libtool
       - name: Install clang-format 20
         run: |
-          sudo apt-get install -y clang-format-20
-          sudo ln -sf /usr/bin/clang-format-20 /usr/bin/clang-format
+          # Download pre-built binary directly
+          cd /tmp
+          wget https://github.com/llvm/llvm-project/releases/download/llvmorg-20.1.1/clang+llvm-20.1.1-x86_64-linux-gnu-ubuntu-22.04.tar.xz
+          tar xf clang+llvm-20.1.1-x86_64-linux-gnu-ubuntu-22.04.tar.xz
+          sudo cp clang+llvm-20.1.1-x86_64-linux-gnu-ubuntu-22.04/bin/clang-format /usr/local/bin/clang-format
           clang-format --version
       - name: Install Re2c
         run: |

README.md

@@ -208,15 +208,23 @@ First, install clang-format:
 
 ```bash
 # macOS
-brew install clang-format
+brew install clang-format@20
+brew link clang-format@20
 
 # Ubuntu/Debian
-sudo apt-get install clang-format
+# Add LLVM repo and install version 20
+wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+sudo apt-add-repository "deb http://apt.llvm.org/$(lsb_release -cs)/ llvm-toolchain-$(lsb_release -cs)-20 main"
+sudo apt-get update
+sudo apt-get install -y clang-format-20
+sudo ln -sf /usr/bin/clang-format-20 /usr/bin/clang-format
 
 # Windows
-choco install llvm
+choco install llvm --version=20.0.0
 ```
 
+> **Important**: This project requires clang-format version 20.x for consistent formatting. Using other versions may result in formatting inconsistencies between local development and CI.
+
 #### Usage
 
 Format all C source files:
@@ -231,6 +239,12 @@ Check formatting without making changes:
 rake format:c_check
 ```
 
+Verbose check that shows differences:
+
+```bash
+rake format:c_verbose
+```
+
 #### Editor Integration
 
 For VS Code users, install the "clangd" extension which will automatically use the project's `.clang-format` file.