QDoc and lupdate will not be compiled

[dalishi]

When build Qt6 on Ubuntu 20 as static from source, configure says QDoc and lupdate will not be compiled because llvm or clang cannot be located. I'm sure the llvm and clang libs have been installed from apt install libclang-dev llvm. I also tried to set the CMAKE_PREFIX_PATH to /usr/lib/llvm-10, it still does not work. Anyone have encountered this issue?

WARNING: QDoc will not be compiled, probably because libclang could not be located. This means that you cannot build the Qt documentation.
Either set CMAKE_PREFIX_PATH or LLVM_INSTALL_DIR to the location of your llvm installation.
On Linux systems, you may be able to install libclang by installing the libclang-dev or libclang-devel package, depending on your distribution.
On macOS, you can use Homebrew's llvm package.
You will also need to set the FEATURE_clang CMake variable to ON to re-evaluate this check.
WARNING: Clang-based lupdate parser will not be available. LLVM and Clang C++ libraries have not been found.
You will need to set the FEATURE_clangcpp CMake variable to ON to re-evaluate this check.

[SGaist]

Hi,

Did you check the configure logs to see what happens with the clang detection ?

[dalishi]

Hi @SGaist I found some info in the log. Am I supposed to set Clang_DIR?

-- Could NOT find Clang (missing: Clang_DIR)
-- Could NOT find WrapLibClang (missing: WrapLibClang_FOUND) (Required is at least version "8")
-- Running syncqt for module: 'QtTools' 
-- Could NOT find Clang (missing: Clang_DIR)
-- Could NOT find WrapLibClang (missing: WrapLibClang_FOUND) (Required is at least version "8")

[SGaist]

Did you do the clang installation prior to the configure call or after ?

If after, do a new configure from a clean state.