Using CMake GLOB_RECURSE to find directories - cmake

Question

I have the following directory structure:
.
├── CMakeLists.txt
└── deps
├── eigen
│   └── include
│   ├── Eigen
│   └── eigen.h
└── osg
├── include
│   └── Osg
└── lib
└── libosg.so
I am trying to get a maximum of the files I don't need to deploy my software, i.e. the libraries.
I tried to create a globbing expression that matches the *.h files and the include directories:
file(GLOB_RECURSE
FOUND_FILES
LIST_DIRECTORIES true
${CMAKE_SOURCE_DIR}/deps/*/include
${CMAKE_SOURCE_DIR}/deps/*/*.h)
message(STATUS "Files are ${FOUND_FILES}")
However, for some reason, the variable FOUND_FILES contains deps/osg/lib. What did I not understand about the GLOB_RECURSE function?
- deps/eigen/include
- deps/eigen/include/eigen.h
- deps/osg/include
- deps/osg/lib
- deps/eigen/include
- deps/osg/include
- deps/osg/lib

Answer 1

I think this could be a workaround:
file(GLOB_RECURSE
FOUND_FILES
LIST_DIRECTORIES true
${CMAKE_SOURCE_DIR}/deps/*/include
)
list(FILTER FOUND_FILES INCLUDE REGEX "^${CMAKE_SOURCE_DIR}/deps/.*/include$")
file(GLOB_RECURSE
tmp
${CMAKE_BINARY_DIR}/deps/*/*.h
)
list(APPEND FOUND_FILES ${tmp})
I guess this is a bug when GLOB_RECURSE is used with LIST_DIRECTORIES true with an expression that has * not on the last entry in the path. Once a directory containing the matched entry is matched in cmake:Glob.cxx#L404, next directories will be added recursively to the output unconditionally at this add_file() in cmake Glob.cxx#L316. So once a ${CMAKE_SOURCE_DIR}/deps/* directory has a include directory or file inside it, all directories recursively from ${CMAKE_SOURCE_DIR}/deps/ are added to the output. Files are not added, as they are checked against the regex at cmake Glob.cxx:#L326.

Answer 2

It appears that CMake drops the last component of the globbing expression when using GLOB_RECURSE to filter directories. This is why CMake does not filter further for the include directory in your example. This may be a bug in the CMake GLOB_RECURSE implementation for directories, or an oversight in the CMake documentation.
EDIT: Solution 1 (does not work):
You can instead simulate recursion using the globbing pattern itself. Use CMake's GLOB instead, and use ** in the globbing pattern to match on anything with one or more characters between deps/ and /include:
file(GLOB
FOUND_FILES
LIST_DIRECTORIES true
${CMAKE_SOURCE_DIR}/deps/**/include
${CMAKE_BINARY_DIR}/deps/**/*.h)
)
message(STATUS "Files are ${FOUND_FILES}")
Solution 2 (ugly):
You could manually add the levels of directories for CMake to search for include folders:
file(GLOB
FOUND_FILES
LIST_DIRECTORIES true
${CMAKE_SOURCE_DIR}/deps/*/include
${CMAKE_SOURCE_DIR}/deps/*/*/include
...
)
However, this is not a very scalable solution.