[CodesInChaos]

> We have already seen early Rust code not compiling with new compiler releases.

Are you talking about breaking changes in the compiler after Rust 1.0? That should be very rare, and generally easy to fix (e.g. by adding a few type annotations).

Or did you use unstable features? (Not sure if embedded is usable without unstable nowadays)

[eldruin]

It depends on your target architecture. For example, embedded development on ARM with stable Rust has been possible since 2018 (Rust 1.31)