为 QDoc 安装 Clang

QDoc uses Clang when parsing C++ files as well as function signatures in \fn commands. Clang is part of the LLVM Compiler Infrastructure Project . If you're going to build QDoc from source, you must install Clang 8.0 or later.

You can get Clang through various channels:

• Qt 提供 prebuilt Clang packages that are used for the Qt binaries in the online installer. These let you link LLVM/Clang libraries statically, but only support Release builds on Windows.
• Linux distributions often provide a package called libclang-dev or libclang-devel . Qt's build system instructs CMake to look for ClangConfig.cmake , so make sure you install the package that provides this file if you want to build QDoc. Running QDoc requires only libclang .
• On macOS, you can also use Homebrew's llvm formula .

注意： the prebuilt binaries from http://releases.llvm.org/download.html cannot be used, as they miss certain components required by QDoc.

If you install Clang in a custom location you need to tell CMake where to find it. This can be done by specifying your LLVM installation path using the LLVM_INSTALL_DIR environment variable when configuring Qt. Alternatively, you can add the installation path to the CMAKE_PREFIX_PATH CMake cache variable.