undefined reference to `WinMain' with cygwin and cmake

Question

I am trying to build a executable with cygwin in windows 7 and I get the following error in the linking stage.

/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/../../../../lib/libcygwin.a(libcmain.o): In function `main':
/usr/src/debug/cygwin-2.3.0-1/winsup/cygwin/lib/libcmain.c:39: undefined reference to `WinMain'
/usr/src/debug/cygwin-2.3.0-1/winsup/cygwin/lib/libcmain.c:39:(.text.startup+0x7f): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `WinMain'
collect2: error: ld returned 1 exit status

I dont understand why it tries to find WinMain. I have a cpp file with int main(int, char**) function defined which is part of the build. I do not understand why it is trying to use libcmain.c, which is part of cygwin during executable creation. I am using cmake and it has following:

add_executable(binary_name ${SOURCE_FILES})

This application need to be a console type application and does not have a GUI.

EDIT: My main function is as follows.

#include "gtest/gtest.h"
int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

I had this once with `#include ` in my sources (see also [here](http://sdl.libsdl.narkive.com/CKVjuSJU/why-do-i-need-a-winmain-if-i-include-windows-h-under-cygwin-but-not-if-i-use-msvc)). But there are a lot of possible causes (see e.g. [here](http://stackoverflow.com/questions/24586808) and more general [here](http://stackoverflow.com/questions/23918318)). If none of this helps, could you please add the command line that is called? Makefiles with verbose output are explained [here](http://stackoverflow.com/questions/2670121) — Florian, Nov 16 '15 at 14:17
`WinMain` is required when linking a [Windows subsystem](https://msdn.microsoft.com/en-us/library/fcc1zstk.aspx) executable. Somewhere in your build, the linker is being told to use the Windows subsystem. Run make with verbose debugging turned on to see the full command passed to the linker. — legalize, Nov 21 '15 at 20:57

score 3 · Answer 1 · edited May 23 '17 at 10:29

Three points I would recommend to check:

Check the command line(s) that are called by activating verbose output. See Using CMake with GNU Make: How can I see the exact commands?
Are you sure that you really have only one main() function in your code?
Is the source file containing main() function directly added to the add_executable() call?

Because I just have given your code a try with the latest CMake package available in Cygwin and it seems to work just fine (with and without #include <windows.h> in main.cpp).

In the hope that it might help finding your problem, here is what I've done:

$ export PATH=/usr/local/bin:/usr/bin:/bin:/usr/bin

$ cmake --version
cmake version 3.3.2
CMake suite maintained and supported by Kitware (kitware.com/cmake).

$ c++ -v --version
c++ (GCC) 4.9.3
gcc-Version 4.9.3 (GCC)
GNU C (GCC) Version 4.9.3 (x86_64-pc-cygwin)
GNU assembler version 2.25 (x86_64-pc-cygwin) using BFD version (GNU Binutils) 2.25
GNU assembler (GNU Binutils) 2.25
GNU ld (GNU Binutils) 2.25

$ cmake ..
-- The CXX compiler identification is GNU 4.9.3
-- Check for working CXX compiler: /usr/bin/c++.exe
-- Check for working CXX compiler: /usr/bin/c++.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found GTest: /cygdrive/c/gtest-1.7.0/lib/.libs/libgtest.a
-- Configuring done
-- Generating done
-- Build files have been written to: ...
Scanning dependencies of target binary_name
[ 50%] Building CXX object CMakeFiles/binary_name.dir/main.cpp.o
[100%] Linking CXX executable binary_name.exe
[100%] Built target binary_name

$ ./binary_name.exe
[==========] Running 0 tests from 0 test cases.
[==========] 0 tests from 0 test cases ran. (3 ms total)
[  PASSED  ] 0 tests.

I've used the following CMakeLists.txt:

cmake_minimum_required(VERSION 3.0)
project(binary_name CXX)

enable_testing()

set(GTEST_ROOT /cygdrive/c/gtest-1.7.0)
set(CMAKE_LIBRARY_PATH ${CMAKE_LIBRARY_PATH} "${GTEST_ROOT}/lib/.libs")

find_package(GTest REQUIRED)

add_executable(binary_name main.cpp)
target_include_directories(binary_name PRIVATE ${GTEST_INCLUDE_DIRS})
target_link_libraries(binary_name PRIVATE ${GTEST_LIBRARIES})

Resulting in the following link line CMakeFiles/binary_name.dir/link.txt:

/usr/bin/c++.exe    
    -Wl,--enable-auto-import CMakeFiles/binary_name.dir/main.cpp.o  
    -o binary_name.exe 
    -Wl,--out-implib,libbinary_name.dll.a 
    -Wl,--major-image-version,0,--minor-image-version,0  
    /cygdrive/c/gtest-1.7.0/lib/.libs/libgtest.a

More References

Most references to similar problems where in combination with SDL or far more general:

Yes I only have one main function. I am adding that file to the executable with other sources. One thing I did not mention here is that I am using CLion IDE here, but it only invokes cmake for building stuff. — user3612009, Nov 18 '15 at 10:58
@user3612009 Ok. Can you please check if my example code works from the command line in your Cygwin environment? Have you tried to add `#include ` to your main.cpp file? And could you please add the verbose makefile output to your question? Just to make sure there is e.g. no `-mwindows` in the linker call. — Florian, Nov 18 '15 at 20:24

undefined reference to `WinMain' with cygwin and cmake

1 Answers1