How to build a library directly from object files with CMake

Question

Given a set of object files, how would you build a static library with CMake ?

With autotools I would do

libXXX.a: $(OBJFILES)
    $(AR) cru $@ $(OBJFILES)
    $(RANLIB) $@

OBJFILES being a list of object files.

How to do that in CMake ?

EDIT: I can't recompile the original cxx files, I have to use the object files (*.o) to create the library.

Answer 1

Add a custom command, something like:

add_custom_command(OUTPUT libXXX.a COMMAND ${AR} cru ${OBJFILES} ).

If necessary you can use add_custom_target and add_dependencies to add your libXXX.a to a specific target, or perhaps to customize the dependencies.

Answer 2

Use add_library in CMakeLists.txt:

add_library(XXX STATIC foo.c bar.cc baz.cxx)