[CMake] Several subprojects in subdirectories

[Igor Polyakov]

Hello, cmake.

I have a directory, where my project is located.
I have three subprojects within subdirectories: "lib", "src" and
"tests" and coresponding source files within each of these subdirectories.

Subprojects have the following dependencies: src -> lib, tests -> lib.

I want to have ability to build all of these subprojects at one time
or build one of them or (more, if there are out-of-date dependencies
between subprojects).

How could I do this with CMake ?

What I've done:
I've written CMakeLists.txt within each of subdirectories, each of
these files specifying, how to make one of subprojects. And I have
written CMakeLists.txt in the top directory with only one line:
SUBDIRS(lib src tests)

What problems do I have:
I don't know, how to specify, that subproject src is dependent from
subproject lib, so it should be built only after library is created.

I tried in src directory:
1.
TARGET_LINK_LIBRARIES(${MyExe} ../lib/MyLib.lib)
Doesn't work, because CMake requires absolute paths.
2.
FIND_LIBRARY(MyLibPath NAMES MyLib PATHS ${MyExe_SOURCE_DIR}/../lib)
TARGET_LINK_LIBRARIES(${MyExe} ${MyLibPath})
Doesn't work when I build "src", when "lib" is not built - CMake could
not find library with such name.

What am I missing ? Please, help !

-- 
Best regards,
 Igor Polyakov                          mailto:igorpol_gbt at mail.ru