Listing include_directories in CMake

Question

I have a cmake build in which I'm searching for a bunch of dependencies, i.e. I have many instances of:

FIND_PACKAGE(SomePackage) if(SOMEPACKAGE_FOUND)   include_directories(${SOMEPACKAGE_INCLUDE_DIR})   link_libraries(${SOMEPACKAGE_LIBRARIES}) endif(SOMEPACKAGE_FOUND) 

Now, I want to add a custom command to build a precompiled header file, but to do this I need to know all of the paths added by my include_directories calls. How can I get a list of these directories (preferably with the proper -I/path/to/directory format) so that I can add them to my custom command?

Answer 1

You can use the get_property command to retrieve the value of the directory property INCLUDE_DIRECTORIES

Something like this:

get_property(dirs DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY INCLUDE_DIRECTORIES) foreach(dir ${dirs})   message(STATUS "dir='${dir}'") endforeach() 

The value of this directory property only tracks the include_directories commands that have occurred previously in the same CMakeLists file, or that have been inherited from previous occurrences in a parent CMakeLists file. If your find_package and include_directories commands are scattered about throughout many subdirectories, this becomes a challenging issue.

If you get to that point, you may consider overriding the include_directories command with your own function or macro and track the values passed to it yourself. Or, simply accumulate them in a global property or an internal cache variable alongside each call to include_directories.

See the documentation here:

http://cmake.org/cmake/help/v2.8.8/cmake.html#command:get_property

http://cmake.org/cmake/help/v2.8.8/cmake.html#prop_dir:INCLUDE_DIRECTORIES

Answer 2

Our solution to write include directories added by conan to a file

function(output_conan_include_dirs)     set(include_dir_str "")     foreach(DIR ${CONAN_INCLUDE_DIRS})         set(include_dir_str "${include_dir_str}${DIR}\n")     endforeach()      set(pth "${CMAKE_BINARY_DIR}/conan-includes.txt")     file(WRITE "${pth}" "${include_dir_str}")     message(STATUS "Conan include directories written to: ${pth}") endfunction()  output_conan_include_dirs()