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I decided to give the built-in CMake support in VS2017 a try, and instead of figuring out why our multi-library, multi-executable project has problems with find_package in the hand-crafted CMakeLists.txt files that it has used for years, I decided to try a simple project first, the FooBar example from the CMake wiki: https://cmake.org/Wiki/CMake/Tutorials/How_to_create_a_ProjectConfig.cmake_file

This project creates a shared library foo and an executable bar that links to this library, and is about as simple as they come. I unzipped the project, opened it with File->Open->Folder, the CMake configuration starts and succeeds. Fist thing I notice is that there's no more Build menu, no F7 shortcut to build my project, but instead, I have to select CMake->Build CMakeLists.txt :-( The Debug menu is similarly stunted, and quick debugging is why I use Visual Studio in the first place. This is already looking bad, but it gets worse:

The build fails with this output:

foo.vcxproj -> C:\Users\Enno\AppData\Local\CMakeBuild\639e9ecd-8891-eb38-b26b-ce84aa448eea\build\x86-Debug\foo\Debug\foo.dll
C:\Users\Enno\AppData\Local\CMakeBuild\639e9ecd-8891-eb38-b26b-ce84aa448eea\build\x86-Debug\bar\LINK : fatal error LNK1104: cannot open file '..\foo\Debug\foo.lib'

Thoughts:

  1. The build directory is in %APPDATA%? That's going to be annoying.
  2. There is indeed no .lib file in that location, just the .dll.

At this point I was becoming skeptical that this may not be a problem with VS2017, but maybe with the sample project itself, or with CMake. So I created a solution for VS2015 with cmake.exe -G "Visual Studio 14" ., which I opened in VS2015 and Voila! I got the same error message.

Is there a CMake genius on SO that can tell me what is wrong with this project?

Enno
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  • I'm beginning to suspect that this is because of the shared library, and related to http://stackoverflow.com/questions/33062728/cmake-link-shared-library-on-windows – Enno Mar 10 '17 at 13:19

1 Answers1

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Turns out: The example on the CMake wiki is not portable in the first place, so this has nothing to do with Visual Studio's built-in CMake support. It does not take into account that Windows needs export libraries for DLLs. Adding the correct __declspec(dllexport) incantations to foo.h resolves the error message.

I found all the information that I needed about shared libraries on Windows at this link: http://gernotklingler.com/blog/creating-using-shared-libraries-different-compilers-different-operating-systems/

Enno
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