Partial build, even for a single top-level target?

Usage
1

Hi!
I really like how modern CMake allows adding sources to a top-level target, from within a subdirectory. Before this, (I think) I needed to have per-subdirectory library targets defined, to have subdir CMakeLists.txt for a top-level executable.

However, now I’m missing the advantage, especially for very large projects, of being able to compile the sources for a subdirectory only (useful e.g. when working on a widely used header): running make in the (binary) subdirectory doesn’t trigger any compiles at all.

How can I trigger rebuilding sources within a subdir only, even when I have a single top-level target?
Thanks

ps: working on Linux, have tried this with makefile and ninja targets

2

Only the Makefiles targets supported this before (though maybe the Ninja generator has it now?). But these are tied to where the add_subdirectory happens and targets are “anchored” to the directory where they are defined. If you want something in between, I suggest OBJECT libraries.