prevent code from compiling if an external project fails to build and install correctly

Question

Is there a way to tell the CMake system that I don't want further compilation until the dependencies (external projects) are built and installed correctly?

Say a project depends on other libraries, which may or may not be present in the system. In case they're not, I use the ExternalProject_Add to download and install it. Yet, even though the configure part goes fine, building the external project doesn't happen until you type make . Now it doesn't make sense to compile the code if building the dependencies failed. I found in CMake ExternalProject_Add() and FindPackage() that maybe adding some dependencies would help, but that answer defines the dependency at configuration time, so it's not relevant to my situation.

Any ideas?

Answer 1

ExternalProject_Add will generate a custom target for building the dependency. If you don't want a target to be built in case building the dependency failed, add a dependency from that target to the external project's target.

ExternalProject_Add(my_external_lib [...])
add_executable(my_program [...])
add_dependencies(my_program my_external_lib)