VS10 always links to SUBSYSTEM:WINDOWS; CMake+SDL+GLEW

Question

I'm just trying to set up a simple project that shall be able to compile on every platform, that is supported by CMake. I started my project on a Win7-system and wrote a little main.cpp that includes SDL.h and GL/glew.h. The style of the main-function is simple c++:

int main(int, char**) {}

In my CMakeLists.txt I call find_package(SDL) and find_package(GLEW). The CMake-part works well, so I just opened the vs10-solution-file and tried to compile when I get the LNK2019:

error LNK2019: unresolved external symbol main referenced in function __tmainCRTStartup

This would mean that I chose the wrong subsystem, doesn't it? But if I simply toggle the subsystem from CONSOLE to WINDOWS and back the problem still exists. Has CMake set a hidden option for that? How can I compile my simple program in vs10?

Answer 1

I had this problem tonight. I'm using CMake to create an MSVC project to build my GLFW app. Of course, the age-old trick for getting rid of the console window if you're using MSVC by itself is to go in to the properties and set "Subsystem" to "Windows" and "Entry Point" to mainCRTStartup, which corresponds to adding the /SUBSYSTEM:WINDOWS /ENTRY:"mainCRTStartup" flags to link.exe, but CMake doesn't provide an easy way to do that.

If you just do a straight-up add_executable() command, you'll get /SUBSYSTEM:CONSOLE /ENTRY:"mainCRTStartup" being passed to the linker.

If you do an add_executable(exename WIN32 ...), you'll get /SUBSYSTEM:WINDOWS.

Gaah! Either option gets us halfway there!

I poked through the .cmake files that CMake ships with (fwiw, I'm using CMake 2.8.10 and Visual Studio 2012 Express), and discovered that the variable that seems to control the /SUBSYSTEM and /ENTRY flags is called CMAKE_CREATE_WIN32_EXE. So to set both parts, we just have to change that variable. Here's what I ended up with, which did the trick:

if(MSVC)
  set(CMAKE_CREATE_WIN32_EXE "/SUBSYSTEM:WINDOWS /ENTRY:\"mainCRTStartup\"")
endif(MSVC)

Hope that helps someone else.