#3939 proposes removing the explicit type conversion string(i) where i has an integer type other than rune. That is a backward incompatible change, so we cannot make it until we can count on having modules everywhere, with the support modules provide for determining the version of the language to use to compile code.

There is a step we can take today, which is to change go vet to report conversions of integer types other than rune to string. If we think that removing this feature from the language is a good idea, then a vet check for it is a good idea, and it is one that we can implement today.