Compiling the unicycle footstep planner in windows

[mebbaid]

The following error is met:

This is basically due to the CMakeLists.txt looking for a .lib extensions, because target_link_libraries doesn't find the associated UnicyclePlanner.lib. One reason would be, I suspect, that the declarative __declspec(dllexport) was not used, and hence the project only builds the .dll file.

One can instead build the project as a static lib and in that case the above error will not be met, but I am not certain what are the implications of that.

[traversaro]

One reason would be, I suspect, that the declarative __declspec(dllexport) was not used, and hence the project only builds the .dll file.

Exactly. See ros/urdfdom#42 for a similar issue.

As documented in the how-to-export-cpp-library I suggest to:

• Use the CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS to export all symbols in the shared libraries on Windows (following the same policy used in Linux/macOS for symbol visibility).
• Do not hardcode the SHARED option in the call to add_library, but rather leave this unspecified (as in https://github.com/robotology/how-to-export-cpp-library/blob/bc184877b002737d457f773fbbcac3bbef4208d3/src/LibTemplateCMake/CMakeLists.txt#L35) but define the standard CMake option BUILD_SHARED_LIBS with a default to ON to leave to the user compiling the library the freedom to compile it as shared or static (this is example necessary for packaging the library in vcpkg).

[traversaro]

@mebbaid Feel free to open a PR with one or even better both of this changes, that @S-Dafarra can review and eventually accept.

[mebbaid]

@traversaro maybe it is strange, but actually it compiled without errors, without having to remove shared
and generated the necessary static libs to link against the .dll objects. an insight into why this is the case would be appreciated.
Edited to add: after option(BUILD_SHARED_LIBS "Build libraries as shared as opposed to static" ON)

[traversaro]

@traversaro maybe it is strange, but actually it compiled without errors, without having to remove shared
and generated the necessary static libs to link against the .dll objects. an insight into why this is the case would be appreciated.

The problem of the missing exported symbols was fixed by setting the CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS . The option(BUILD_SHARED_LIBS ...) and removing SHARED from add_library part are necessary to give to the user the freedom to compile the library as static, but they do not change the fact that by default the library is compiled as shared.

[S-Dafarra]

Solved with #13