CMake - combine multiple libraries into one

Let's say I have executables A, B, C, and I have external libraries X, Y, Z

SET(EXTERNAL_LIB X Y Z)
TARGET_LINK_LIBRARIES(A, ${EXTERNAL_LIB})
TARGET_LINK_LIBRARIES(B, ${EXTERNAL_LIB})
TARGET_LINK_LIBRARIES(C, ${EXTERNAL_LIB})

However, if I visualize this (using cmake --graphviz option, I get a complex bipartite graph with edges from each of the executables A, B, and C to each of开发者_JAVA技巧 the libraries X, Y, and Z.

I was wondering if there's a way to combine all the libraries into one.

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All of this depends a bit on your platform, compiler and the type of libraries:

1. In case, you can build X, Y, Z yourself: Create a new project XYZ, built from the aggregated source files of X, Y and Z. But I guess if this was possible, you would not have asked on SO.

2. If you can not rebuild the libs and they were built as a shared libraryy (dll/so), you are out of luck. You could try to write a wrapper library, which hides all the internals of X, Y and Z and which will be used by applications A, B and C.

3. If they were build as static libs, take a look at this SO question. Because a static lib is not much more than an archive of object files, you may be able to extract the object code from each lib and recombine them with ar.

But why would you? Suppose you get a fourth application D, which only depends on X. Then you would need the separate library Y anyway (unless you prefer to unnecessarily link with all libs).