FormatFloat() overflow bug on 32bit systems

[TerraTech]

I ran into a bug tonight compiling a 32bit version and found FormatFloat() was overflowing an int somewhere. My program is dealing with nanosecond time calculations and I'm humanizing a scaling factor.

Interestingly enough, Commaf() doesn't have the same problem.

package main
import (
	"fmt"
	"math"
	"github.com/dustin/go-humanize"
)

func main() {
	var a float64 = 52746220055.92342
	fmt.Println(math.MaxFloat64)
	fmt.Println(humanize.Commaf(a))
	fmt.Println(">>> " + humanize.FormatFloat("#,###.##", a))
}

#64bit
$ go run main.go
1.7976931348623157e+308
52,746,220,055.92342
>>> 52,746,220,055.92

#32bit
$ GOARCH=386 go run main.go
1.7976931348623157e+308
52,746,220,055.92342
>>> -2,147,483,648.92

[dmitshur]

There are 3 places or so inside humanize.FormatFloat that use int. I suspect that's where the issue likely lies. A fix could be to always use int64.

[dustin]

Anyone happen to know how to force 32-bit for tests? Guess I need more CI here. I've got a few arm boxes I run at home I could employ.

…

On Mon, Jan 9, 2017, 10:58 Dmitri Shuralyov ***@***.***> wrote: There are 3 places or so inside humanize.FormatFloat that use int. I suspect that's where the issue likely lies. A fix could be to always use int64. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#46 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAG8xKZtAsYeCijRoHg7iwUvFKU6OTwks5rQoMlgaJpZM4LeEmE> .

[dmitshur]

Anyone happen to know how to force 32-bit for tests?

Perhaps something like:

GOARCH=386 go test

travis-ci/travis-ci#6126 appears to be related.