[almostgotcaught]

> How is it any different from ordinary parallel compilation? Make will happily use dozens of CPU cores for compilation, even if linking and other operations must be synchronous

It's not any different because ordinary compilation isn't parallelizable either. Chopping up your program into TUs is a work around for the fact that it isn't, not proof that it is. Think about it: why does ODR exist? Why does LTO exist? Also think about it: is linking parallelizable?

[nuudlman]

Linking is very parallelizable: see the mold linker for a demonstration.

[almostgotcaught]

I feel no one in these comments knows the difference between weak scaling and strong scaling.