This page gives you the shortest path to checking out Clang and demos a few options. This should get you up and running with the minimum of muss and fuss. If you like what you see, please consider getting involved with the Clang community. If you run into problems, please file bugs on the LLVM bug tracker . Release Clang Versions Clang is released as part of regular LLVM releases. You can download the release versions from https://llvm.org/releases/ . Clang is also provided in all major BSD or GNU/Linux distributions as part of their respective packaging systems. From Xcode 4.2, Clang is the default compiler for Mac OS X. Building Clang and Working with the Code On Unix-like Systems If you would like to check out and build Clang, the current procedure is as follows: Get the required tools. See Getting Started with the LLVM System - Requirements . Note also that Python is needed for running the test suite. Get it at: https://www.python.org/downloads/ Standard build process uses CMake. Get it at: https://cmake.org/download/ Check out the LLVM project: Change directory to where you want the llvm directory placed. git clone https://github.com/llvm/llvm-project.git The above command is very slow. It can be made faster by creating a shallow clone. Shallow clone saves storage and speeds up the checkout time. This is done by using the command: git clone --depth=1 https://github.com/llvm/llvm-project.git (using this only the latest version of llvm can be built) For normal users looking to just compile, this command works fine. But if someone later becomes a contributor, since they can't push code from a shallow clone, it needs to be converted into a full clone: cd llvm-project git fetch --unshallow Build LLVM and Clang: cd llvm-project mkdir build (in-tree build is not supported) cd build This builds both LLVM and Clang in release mode. Alternatively, if you need a debug build, switch Release to Debug. See frequently used cmake variables for more options. cmake -DLLVM_ENABLE_PROJECTS=clang -DCMAKE_BUILD_TYPE=Release -G "Unix Makefiles" ../llvm make Note: For subsequent Clang development, you can just run make clang . CMake allows you to generate project files for several IDEs: Xcode, Eclipse CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3. For more details see Building LLVM with CMake page. On Linux, you may need GCC runtime libraries (e.g. crtbeginS.o, libstdc++.so ) and libstdc++ headers. In general, Clang will detect well-known GCC installation paths matching the target triple (configured at build time (see clang --version ); overriden by --target= ) and use the largest version. If your configuration fits none of the standard scenarios, you can set --gcc-install-dir= to the GCC installation directory (something like /usr/lib/gcc/$triple/$major ). If your GCC installation is under /usr/lib/gcc but uses a different triple, you can set --gcc-triple=$triple . Try it out (assuming you add llvm/build/bin to your path): clang --help clang file.c -fsyntax-only (check for correctness) clang file.c -S -emit-llvm -o - (print out unoptimized llvm code) clang file.c -S -emit-llvm -o - -O3 clang file.c -S -O3 -o - (output native machine code) Run the testsuite: make check-clang See Getting Started with the LLVM System - Requirements . Note also that Python is needed for running the test suite. Get it at: https://www.python.org/downloads/ Standard build process uses CMake. Get it at: https://cmake.org/download/ Check out the LLVM project: Change directory to where you want the llvm directory placed. git clone https://github.com/llvm/llvm-project.git The above command is very slow. It can be made faster by creating a shallow clone. Shallow clone saves storage and speeds up the checkout time. This is done by using the command: git clone --depth=1 https://github.com/llvm/llvm-project.git (using this only the latest version of llvm can be built) For normal users looking to just compile, this command works fine. But if someone later becomes a contributor, since they can't push code from a shallow clone, it needs to be converted into a full clone: cd llvm-project git fetch --unshallow Change directory to where you want the llvm directory placed. git clone https://github.com/llvm/llvm-project.git The above command is very slow. It can be made faster by creating a shallow clone. Shallow clone saves storage and speeds up the checkout time. This is done by using the command: git clone --depth=1 https://github.com/llvm/llvm-project.git (using this only the latest version of llvm can be built) For normal users looking to just compile, this command works fine. But if someone later becomes a contributor, since they can't push code from a shallow clone, it needs to be converted into a full clone: cd llvm-project git fetch --unshallow git clone --depth=1 https://github.com/llvm/llvm-project.git (using this only the latest version of llvm can be built) For normal users looking to just compile, this command works fine. But if someone later becomes a contributor, since they can't push code from a shallow clone, it needs to be converted into a full clone: cd llvm-project git fetch --unshallow cd llvm-project git fetch --unshallow Build LLVM and Clang: cd llvm-project mkdir build (in-tree build is not supported) cd build This builds both LLVM and Clang in release mode. Alternatively, if you need a debug build, switch Release to Debug. See frequently used cmake variables for more options. cmake -DLLVM_ENABLE_PROJECTS=clang -DCMAKE_BUILD_TYPE=Release -G "Unix Makefiles" ../llvm make Note: For subsequent Clang development, you can just run make clang . CMake allows you to generate project files for several IDEs: Xcode, Eclipse CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3. For more details see Building LLVM with CMake page. cd llvm-project mkdir build (in-tree build is not supported) This builds both LLVM and Clang in release mode. Alternatively, if you need a debug build, switch Release to Debug. See frequently used cmake variables for more options. cmake -DLLVM_ENABLE_PROJECTS=clang -DCMAKE_BUILD_TYPE=Release -G "Unix Makefiles" ../llvm Note: For subsequent Clang development, you can just run make clang . CMake allows you to generate project files for several IDEs: Xcode, Eclipse CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3. For more details see Building LLVM with CMake page. On Linux, you may need GCC runtime libraries (e.g. crtbeginS.o, libstdc++.so ) and libstdc++ headers. In general, Clang will detect well-known GCC installation paths matching the target triple (configured at build time (see clang --version ); overriden by --target= ) and use the largest version. If your configuration fits none of the standard scenarios, you can set --gcc-install-dir= to the GCC installation directory (something like /usr/lib/gcc/$triple/$major ). If your GCC installation is under /usr/lib/gcc but uses a different triple, you can set --gcc-triple=$triple . Try it out (assuming you add llvm/build/bin to your path): clang --help clang file.c -fsyntax-only (check for correctness) clang file.c -S -emit-llvm -o - (print out unoptimized llvm code) clang file.c -S -emit-llvm -o - -O3 clang file.c -S -O3 -o - (output native machine code) clang file.c -fsyntax-only (check for correctness) clang file.c -S -emit-llvm -o - (print out unoptimized llvm code) clang file.c -S -emit-llvm -o - -O3 clang file.c -S -O3 -o - (output native machine code) Run the testsuite: make check-clang make check-clang Using Visual Studio The following details setting up for and building Clang on Windows using Visual Studio: Get the required tools: Git . Source code control program with its packaged bash tools. Get it from: https://git-scm.com/download or install the component Git For Windows bundled with Visual Studio. In addition to source code control, the GNU core utilities in the package are used by the tests. CMake . This is used for generating Visual Studio solution and project files. Get it from: https://cmake.org/download/ Visual Studio 2019 16.7 or later . This tutorial assumes Visual Studio 2022. Python . It is used to run the clang test suite. Get it from: https://www.python.org/download/

Git . Source code control program with its packaged bash tools. Get it from: https://git-scm.com/download or install the component Git For Windows bundled with Visual Studio. In addition to source code control, the GNU core utilities in the package are used by the tests. CMake . This is used for generating Visual Studio solution and project files. Get it from: https://cmake.org/download/ Visual Studio 2019 16.7 or later . This tutorial assumes Visual Studio 2022. Python . It is used to run the clang test suite. Get it from: https://www.python.org/download/ Check out LLVM and Clang: git clone https://github.com/llvm/llvm-project.git Note : Some Clang tests are sensitive to the line endings. Ensure that checking out the files does not convert LF line endings to CR+LF. If you're using git on Windows, make sure your core.autocrlf setting is false. git clone https://github.com/llvm/llvm-project.git Note : Some Clang tests are sensitive to the line endings. Ensure that checking out the files does not convert LF line endings to CR+LF. If you're using git on Windows, make sure your core.autocrlf setting is false. Run CMake to generate the Visual Studio solution and project files: cd llvm-project mkdir build (for building without polluting the source dir) cd build If you are using Visual Studio 2022: cmake -DLLVM_ENABLE_PROJECTS=clang -G "Visual Studio 17 2022" -A x64 -Thost=x64 ..\llvm -Thost=x64 is required, since the 32-bit linker will run out of memory. To generate x86 binaries instead of x64, pass -A Win32 . See the LLVM CMake guide for more information on other configuration options for CMake. The above, if successful, will have created an LLVM.sln file in the build directory. cd llvm-project mkdir build (for building without polluting the source dir) If you are using Visual Studio 2022: cmake -DLLVM_ENABLE_PROJECTS=clang -G "Visual Studio 17 2022" -A x64 -Thost=x64 ..\llvm -Thost=x64 is required, since the 32-bit linker will run out of memory. To generate x86 binaries instead of x64, pass -A Win32 . See the LLVM CMake guide for more information on other configuration options for CMake. The above, if successful, will have created an LLVM.sln file in the build directory. Build Clang: Open LLVM.sln in Visual Studio. Build the "clang" project for just the compiler driver and front end, or the "ALL_BUILD" project to build everything, including tools. Open LLVM.sln in Visual Studio. Build the "clang" project for just the compiler driver and front end, or the "ALL_BUILD" project to build everything, including tools. Try it out (assuming you added llvm/debug/bin to your path). (See the running examples from above.) See Hacking on clang - Testing using Visual Studio on Windows for information on running regression tests on Windows. Using Ninja alongside Visual Studio We recommend that developers who want the fastest incremental builds use the Ninja build system . You can use the generated Visual Studio project files to edit Clang source code and generate a second build directory next to it for running the tests with these steps: Check out clang and LLVM as described above Open a developer command prompt with the appropriate environment. If you open the start menu and search for "Command Prompt", you should see shortcuts created by Visual Studio to do this. To use native x64 tools, choose the one titled "x64 Native Tools Command Prompt for VS 2022". Alternatively, launch a regular cmd prompt and run the appropriate vcvarsall.bat incantation. To get the 2022 x64 tools, this would be: "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvarsall.bat" x64 If you open the start menu and search for "Command Prompt", you should see shortcuts created by Visual Studio to do this. To use native x64 tools, choose the one titled "x64 Native Tools Command Prompt for VS 2022". Alternatively, launch a regular cmd prompt and run the appropriate vcvarsall.bat incantation. To get the 2022 x64 tools, this would be: "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvarsall.bat" x64 mkdir build_ninja (or build , or use your own organization) set CC=cl (necessary to force CMake to choose MSVC over mingw GCC if you have it installed) cmake -GNinja -DLLVM_ENABLE_PROJECTS=clang ..\llvm ninja clang This will build just clang. ninja check-clang This will run the clang tests. Clang Compiler Driver (Drop-in Substitute for GCC) The clang tool is the compiler driver and front-end, which is designed to be a drop-in replacement for the gcc command. Here are some examples of how to use the high-level driver: The 'clang' driver is designed to work as closely to GCC as possible to maximize portability. The only major difference between the two is that Clang defaults to gnu99 mode while GCC defaults to gnu89 mode. If you see weird link-time errors relating to inline functions, try passing -std=gnu89 to clang. Examples of using Clang Pretty printing from the AST: Note, the -cc1 argument indicates the compiler front-end, and not the driver, should be run. The compiler front-end has several additional Clang specific features which are not exposed through the GCC compatible driver interface. Code generation with LLVM: