GoLang力计算在运行时进行，而不是在编译时进行

I am working on a project which should be available as either 64bit or 32bit.

Due to 3rd party driver, I am forced to work with int, rather than int64.

const (
    _   = iota // ignore zero iota
    KiB = 1 << (10 * iota)
    MiB
    GiB
    TiB
)

func doSomething() (ok bool) {
    if strconv.IntSize != 64 {
        // exiting early from function because default int is not 64bit.

        return false
    }

    ThirdPartyDriverBytes = 5 * GiB

    return true
}

Unfortunately the compiler complains, I get a constant 5368709120 overflows int error.

How can I effectively work around this issue? Is there a way I can force this 5 * GiB calculation to occur at runtime?

I have found a workaround... 5 * GiB is a constant expression, so gets computed by the compiler.

By splitting up into multiple statements, it no longer happens.

defaultBytes := 5
ThirdPartyDriverBytes = defaultBytes * GiB

Just explicitly type the variable to int64 instead of the platform-dependent int:

var ThirdPartyDriverBytes int64
const (
    _  int64 = iota // ignore zero iota
    KiB = 1 << (10 * iota)
    MiB
    GiB
    TiB
)

This is clearer than trying to work around the compiler inferring types from constant expressions.