您如何从Go中的int转换溢出中得到错误？

Question

I'm looking for integer conversion functions resembling this:

func narrow(x int64) (int32, error) { ... }

In this example, the function would return ((int32)(x), nil) if x fits into an int32, and (nil, someError) if it doesn't.

There seem to be a lot of conversions built into the language, but they all silently swallow overflows, rather than providing a reified error. Am I missing something?

Answer 1

The conversions do not report overflow.

Here's a function that handles positive and negative numbers:

func narrow(x int64) (int32, error) {
   y := int32(x)
   if int64(y) != x {
      return 0, errors.New("overflow")
   }
   return y, nil
}

playground example