[thenewwazoo]

I'm a bit surprised to read this. It's been a long time since I've done C++ outside of the embedded space, but isn't this a problem that's solved by libraries and LTO? Compiling individual source units isn't terribly difficult either. There's a single tool that turns source files into object files, and a single tool to link them all up. It all feels very UNIX-y to me.

[weberc2]

LTO is unrelated. Compiling individual units is only one of many build system responsibilities. There's also dependency management, cross-platform support, iterative builds, etc. And it all needs to be fast.