[CMake] Unify entire tree into a single static library?

[Verweij, Arjen]

Doug,

There is no convenient way to do this in Cmake you have you program around this issue with a GLOBAL  list of source files.

Michael Wild has offered a nice example at http://www.mail-archive.com/cmake@cmake.org/msg27780.html

Hopefully this is useful to you as well.

Regards,
Arjen

From: cmake-bounces at cmake.org [mailto:cmake-bounces at cmake.org] On Behalf Of Doug
Sent: woensdag 23 februari 2011 6:48
To: cmake at cmake.org
Subject: [CMake] Unify entire tree into a single static library?

Hi,

If this has been answered somewhere already in the WIKI or something, please just link me up; it seems like a simple question, but I can't figure it out.

So, basically I have my code split into a series of sub-directories:

project/
project/utils/
project/common/
project/desktop/
etc.

Each sub directory currently has it's own CMakeLists.txt, as follows:

file(GLOB SOURCE *.c)
add_library (shared ${SOURCE})

The parent CMakeLists.txt file define these as dependencies:

# Shared code
include_directories("${PROJECT_SOURCE_DIR}/shared")
add_subdirectory(shared)
set (EXTRA_LIBS ${EXTRA_LIBS} shared)

# Utility libraries
include_directories("${PROJECT_SOURCE_DIR}/utils")
add_subdirectory(utils)
set (EXTRA_LIBS ${EXTRA_LIBS} utils)

...

# Source files~
file(GLOB sources src/*.c)
add_library (project ${sources})
target_link_libraries (project ${EXTRA_LIBS})

This builds fine. However, it generates a library.a file for each directory, eg.

per-ms006:build douglasl$ du -a |grep "\.a"
./desktop/libdesktop.a
./libcommon.a
./shared/libshared.a
./utils/libutils.a

The problem is that if I want to depend on this with an external project, I can do so via this:

# Add lib
include_directories("/path/to/project/include/")
link_directories("/path/to/project/build/")
set(EXTRA_LIBS ${EXTRA_LIBS} project)

...but....... obviously this does not link any of the other sub libraries like -lutils -lcommon -ldesktop, so my build fails with a pile of undefined symbol errors. 

So, what's the way to solve this?

Can I either:

1) Somehow depend on an external project directory with some kind of add_subdirectory() directive?

2) Somehow force cmake to combine all the symbols into a single static library for the project, rather than several individual ones?

(The only suggestions I've seen so far are (2), where you define a single CMakeLists,txt and list _all_ source files in all directories in it. This is a silly solution, or (2) where you manually uncompress the .a files and recombine all the .o files into a single .a file. This is also just ridiculous. Surely this is a problem that comes up a lot...?)

Cheers,
Doug.