I think OP is looking at backward compatibility with respect to libraries. For example today I make a library that does a lot of computations in `const` functions and it works with rust 1.72.0; tomorrow I slightly change function by splitting a statement into two, and now suddently the evaluation becomes too long and my dependents don't compile anymore.

Though to be honest this problem existed even before rust 1.72.0 and likely can't be solved while preventing infinite computations.