[CMake] Mingw64: add a statically linked library adds libstdc++ dependency

[William Zeitler]

What finally worked was:

set(CMAKE_CXX_STANDARD_LIBRARIES "-static-libgcc -static-libstd++ 
${CMAKE_CXX_STANDARD_LIBRARIES})

if(MINGW)
     set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} 
-Wl,-Bstatic,--whole-archive -lwinpthread -Wl,--no-whole-archive")
endif()

Thanks!

On 6/17/19 02:16, Eric Dönges wrote:
> On 15.06.19 21:33, William Zeitler wrote:
>> In the example below, two lines are marked "COMMENT ME OUT": one in
>> hello_c/main.cpp and the other in hello_c/CMakeLists.txt. If you comment
>> these out, the reference to the hello_lib library is removed; the
>> project builds and the executable executes on Windows 10 without a
>> libstdc++ dependency. If you uncomment the two lines, the function in
>> the hello_lib library is linked in; the project builds, but won't
>> execute on Windows 10 due to the libstdc++ dependency. (Note: in
>> powershell it silently fails, in an old-school dos/cmd box it displays
>> an error message.)
> I think your problem is that CMAKE_CXX_FLAGS are only used when
> compiling, not linking, so your hello_lib is linked without the "-static
> -static-libgcc -static-libstdc++" options and thus links against the
> shared libstdc++. You could try either of the following:
>
> 1) Add a "target_link_libraries(hello_lib -static-libgcc
> -static-libstdc++)".
>
> 2) Add "string(APPEND CMAKE_SHARED_LINKER_FLAGS "-static-libgcc
> -static-libstdc++)" to your project. Note that this will probably need
> to be done before defining any of your (library) targets. Also note that
> this will link any shared library in your project with the static
> libstdc++, which may or may not be what you want.
>
> Disclaimer - I haven't tried if any of this actually solves your
> problem; I just think it should.