In order to build and contribute to ClickHouse, you must use LLVM and Clang.
These are the commands to build the latest version of LLVM and Clang on Linux:
git clone [email protected]:llvm/llvm-project.git
mkdir llvm-build
cd llvm-build
cmake -GNinja -DCMAKE_BUILD_TYPE:STRING=Release -DLLVM_ENABLE_PROJECTS=all -DLLVM_TARGETS_TO_BUILD=all ../llvm-project/llvm
time ninja
sudo ninja install