Sure. My point is that this is similar to what we guarantee: the compiler used to compile some code, and now it won't. As they say, "It has therefore been disallowed in Go 1.4, which is a breaking change, although very few programs will be affected." Our breaking changes have been similar.
Rust has rfcs, and many of the "breaking changes" are in places where the implementation didn't follow the RfC. Others were in things that were never intended to compile. Its effectively the same thing.
