How do you keep toolchain drift across windows, linux, and mac manageable at 30+ engineers?

We're about 30 engineers split across Windows and Linux, with a handful on macOS. All C++, CMake + Ninja as the build sytem. The compiler situation is where it gets messy. Someone's always on a slightly different version and it surfaces in the strangest ways, usually right before a release.

We've gone back and forth on a few approaches...pinning versions across machines, containerizing the build environment, leaning on build servers and treating local builds as second-class, or some mix. None feel clean. All have tradeoffs, and the tradeoff's shift depending on the platform.

What's held up at a similar scale?

https://redd.it/1uev7qr
@r_cpp