Mingw32 无法静态链接到 libgcc_s_dw2-1、libstdc++-6、libwinpthread-1 (Qt 5.7.1)

Question

I am struggling with a problem of statically linking with libgcc_s_dw2-1, libstdc++-6, libwinpthread-1 libraries when compiling with mingw32. Setting up a project with -static-libgcc -static-libstdc++ -static -lwinpthread flags helps in case if I build a standalone application. But when I use Qt 5.7.1 for mingw32 compiler, it does not help. The application won't start complaining that these libs are missing!

Here is my CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(dummyapp LANGUAGES CXX)

find_package(Qt5 REQUIRED COMPONENTS Core)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static-libgcc -static-libstdc++ -static -lwinpthread")

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED TRUE)

add_executable(app
        app.cpp)

target_link_libraries(app
        PRIVATE
            Qt5::Core
        )

add_custom_command(TARGET app PRE_LINK
        COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:Qt5::Core> $<TARGET_FILE_DIR:app>
        )

app.cpp

#include <iostream>
#include <QVariant>

int main(int argc, const char **argv)
{
    std::cout << "Hello dummy!" << std::endl;

    QVariant var{};

    std::cin.get();

    return 0;
}

I suspect, that the reason for this behavior is that Qt itself was built linking to those libs dynamically.

What is the solution? Is there a remedy? If not, how can I deploy those libs automatically on build?

Answer 1

If your build and it's dependancies aren't static, those DLLs need to be distributed with your application. The article at https://lwn.net/Articles/549573/ explains the libstdc++-6 DLL can be distributed without licensing issues.