I have the same problem. I often work in a modular way that imply that I work a lot of time in the same cpp file, compiling through coding to check my assumptions.
Now working on templates makes it worse if you have to recompile the whole (massive) application just to check that you have at least the typo right.
I think a separate compilation command in the project setting(or more global?) might be a solution. It would take a file as parametter and would be used when the user wants just to compile (and only compile, not link, neither do some build scripts etc.)
If that makes the implementtion of this feature easier, a simple implementation would make the project compilation just ignore the unique compilation of a cpp even if the user just compiled each cpp separately.