How do I set up CMake to generate header-only projects?

Question

I want to set up header-only C++ (or C) library projects, but can't find a clean way.

After some searches I've found that you can't set up a normal library using add_library to do this because it requires a compilable source file. A way to do this would be to use add_custom_target instead, this way:

# Get all headers (using search instead of explicit filenames for the example) file( GLOB_RECURSE XSD_HEADERS      *.hxx ) add_custom_target( libsxsd SOURCES ${XSD_HEADERS} ) 

But that doesn't seem to work completely here as I can't see the sources in the project generated in VS2010. I don't know if it's a bug or if I'm doing it wrong or if there is a preferred way to do this.

Answer 1

Update: CMake will soon include a library target called INTERFACE that is ideal for header-only projects. This feature is currently in the master branch. Reference.

Using the command add_custom_target as you propose works for me (VS2010). The files are neatly listed within my project but it has the drawback that you can't define any "Additional Include Directories" with a custom target. Instead, I now use the following:

add_library(HEADER_ONLY_TARGET STATIC test1.hpp test2.hpp) set_target_properties(HEADER_ONLY_TARGET PROPERTIES LINKER_LANGUAGE CXX) 

This sets up your header-only project as a dummy archive target. Don't worry, no actual binaries will be generated if you should try and build it (at least not in VS2010 and Xcode 4). The command set_target_properties is there because CMake will otherwise complain that it cannot infer the target language from .hpp files only.