Suppose I have such project structure:
Root
+ ProjA
+ SubA.1
+ SubA.2
+ ProjB
+ SubB.1
+ SubB.2
And the dependencies I setup is:
SubA.2 depends on SubA.1
ProjA depends on SubA.1 and SubA.2
ProjB depends on ProjA
I want to make the build order looks like this when start with make -jX:
1. SubA.1
2. SubA.2
3. SubB.1 SubB.2
But the fact is:
1. SubA.1 SubB.1 SubB.2
2. SubA.2
It seems the ProjB => ProjA can't be used to make all the SubBs build after SubAs.
How can I make all the SubBs build after all the SubAs finishes?
In CMake dependencies can be set only on per-target basis.
You should decide, whether ProjB depends on internals of ProjA or not. By "internals" I mean names of targets, values of CMake variables and so on.
- If
ProjB actually require internals of ProjA, you may carefully determine targets of ProjA, which are required for one or another target of ProjB, and set only needed dependencies. Such a way building of ProjA may interleave with ProjB with make -j, but building will be correct.
E.g., if SubB.1 is executable, which requires SubA.1 library for link with, then
target_link_libraries(SubB.1 SubA.1)
automatically sets needed dependencies.
If SubB.2 is generated using executable SubA.2, then usage
add_custom_command(OUTPUT <subB.2_file>
COMMAND SubA.2 <args>
)
will automatically set needed dependencies.
- If
ProjB doesn't aware about internal of ProjA and it is only known that ProjB can be built only when ProjA is already built, then you may use ExternalProject_Add for build both projects and set dependencies between created targets:
CMakeLists.txt:
ExternalProject_Add(ProjA ...)
ExternalProject_Add(ProjB ...)
# Now `ProjA` and `ProjB` are targets in top-level project.
add_dependencies(ProjB ProjA)
