Cross Compiling a Qt5 App using Clang and CMake

Example that uses CMake, Clang, and Qt to cross compile a simple application for Windows with MSVC compatibility.

Parts of it based on: https://gist.github.com/HiImJulien/3eb47d7d874fe5483810bd77940e74c0

Requirements

• Clang Version >= 10
• Visual Studio Build Tools: https://visualstudio.microsoft.com/downloads/
  • The following components are sufficient:
    • MSVC v142 - VS 2019 C++-x64/x86-Buildtools (v14.28)
    • Windows 10 SDK (10.0.19041.0)
• Qt5: https://download.qt.io/official_releases/qt
  • again when installing it is sufficient to install msvc version of Qt5

Instructions Linux

Requirements:

• Qt5 development packages
• Clang 10

Steps

• Copy MSVC build tools into the project directory:
  • Copy C:/Program Files (x86)/Microsoft Visual Studio/2019/BuildTools/VC/Tools/MSVC/<MSVC Version> to msvc_build_tools/MSVC
• Copy Windows SDK into the project directory:
  • From C:/Program Files (x86)/Windows Kits/10 copy the folders
    • Include to msvc_build_tools/Kit
      • Lib to msvc_build_tools/Kit
  • Both directories have sub directories with the Windows SDK Version as name.
  • Adjust clang_windows_toolchain.cmake to use the proper Windows SDK Version in variable WINSDK_VER
• Copy the Qt5 msvc development files into the project directory:
  • Copy C:/Qt/Qt5.12.10/5.12.10/msvc2017_64 to qt5_msvc2017_64
• Configure project using: cmake -DCMAKE_TOOLCHAIN_FILE=clang_windows_toolchain.cmake <project dir>

Instructions Windows with JetBrains CLion

Requirements:

• Download and Install Qt5 (MinGW libraries not needed)
• Clang 10 (https://releases.llvm.org/download.html)
• Install MinGW Make
• Install JetBrains CLion (https://jetbrains.com/clion)

Steps (VS Toolchain)

• Open project
• Adjust Toolchain
  • Choose Visual Studio Toolchain
• Set CMake Options to: -DCMAKE_BUILD_TYPE=Debug -DCMAKE_C_COMPILER=C:/llvm/bin/clang-cl.exe -DCMAKE_CXX_COMPILER=C:/llvm/bin/clang-cl.exe -DCMAKE_C_FLAGS=-m64 -DCMAKE_CXX_FLAGS=-m64 -DCMAKE_LINKER=c:/llvm/bin/lld-link.exe

Steps (MinGW Toolchain)

• Open project
• Adjust Toolchain
  • Go to Toolchain Settings
  • Remove existing Visual Studio Toolchain
  • Add MinGW Toolchain
• Adjust CMake Profiles
  • Add -DCMAKE_TOOLCHAIN_FILE=clang_windows_toolchain.cmake as CMake parameters

TODO: How to set up debugger?