Using PUBLIC FILE_SET HEADERS with dependent targets

Usage
1

Hey folks, I’m in a bit of bind trying to understand target_sources(<name> PUBLIC FILE_SET HEADERS ... and how a target dependent on a library that uses this works.

Here’s my situation, setup, and issue.
I’ve got a third party library which we’ve introduced CMake to and has a directory structure as follows:

  • library/
    • CMakeLists.txt - has the following:
      add_library(...) and target_sources(library PUBLIC FILE_SET HEADER BASE_DIRS ${CMAKE_CURRENT_SOURCE_DIR})
    • inc/
      • CMakeLists.txt (includes a bunch of subdirectories)
      • Framework
        • Framework.hpp
        • Framework.cpp
        • CMakeLists.txt - has the following:
          target_sources(library PUBLIC FILE_SET HEADERS FILES ${HXX_FILES} PRIVATE ${OUT_CXX_FILES})
          target_include_directories(${MAX_LIB_TARGET} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
      • Utility/
        • CMakeLists.txt - has a similar layout to Framework with source files, but also has subdirectories which follow the same structure
        • Math/
          • CMakeLists.txt - …

So, this library builds correctly, and it installs properly into the /usr/local/... directories.
Now, the application that depends on this library uses CPM for a couple reasons, but one of them is that if the version cannot be found locally then CPM is a nice wrapper to go pull the correct one.
As it stands, if the available version is locally installed, then the application builds and links correctly.

However, if I try to use an upstream version, or local source, I end up with issues where the application cannot find the header files. In fact, the path to the header files is not even on the command line for gcc (neither -I or -isystem).
Here is what the application looks like

  • app/
    • CMakeLists.txt
      add_executable(app app.cpp)
      target_include_directories(app PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
      target_link_libraries(app PRIVATE library)

That’s it. There’s not a whole lot else.
Can someone help me determine if what I’m trying to do is possible with CMake. I believe it is, but I’m lost in terms of setting up the CMakeLists.txt correctly.

Cheers

2

Just bumping to see if anyone has feedback or ideas on this?

3

Can you print out the include directory properties of your library like so, in app/CMakeLists.txt:

cmake_print_properties(TARGETS library  PROPERTIES
                       INTERFACE_INCLUDE_DIRECTORIES INCLUDE_DIRECTORIES)

That may give you an idea

4

This does not give the right path to consumers. Since you are using FILE_SET HEADERS, I think you just want to set BASE_DIRS and install the FILE_SET. That will set up the include directory usage requirements automatically.

If that doesn’t work, please provide an example that can be executed directly to aid in figuring out what’s up.

5

You may try it like this snippet:

# ...
# Write spglib_export.h to the current binary directory
include(GenerateExportHeader)
generate_export_header(Spglib_symspg
	EXPORT_FILE_NAME spglib_export.h
	EXPORT_MACRO_NAME API_SPGLIB
)
configure_file(spglib.h spglib.h COPYONLY)

target_sources(Spglib_symspg
	PUBLIC
		FILE_SET HEADERS
		BASE_DIRS ${CMAKE_CURRENT_BINARY_DIR}
		FILES
			${CMAKE_CURRENT_BINARY_DIR}/spglib_export.h
			${CMAKE_CURRENT_BINARY_DIR}/spglib.h
)
target_include_directories(Spglib_symspg
		PRIVATE "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>"
		PUBLIC
		"$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>"
		"$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
)
# ...
6

This is what FILE_SET TYPE HEADERS should do automatically (with a PRIVATE fileset for the source tree at least).

1 Like
7

Yes, it works.