fmt.Println fails to print math.MaxUint64

[ghost]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

play.golang.org

What operating system and processor architecture are you using (go env)?

play.golang.org

What did you do?

package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Println(math.MaxUint64)
}

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

https://play.golang.org/p/5GARX4Q2Tc

What did you expect to see?

Successful compilation and math.MaxUint64 in standard output

What did you see instead?

main.go:9: constant 18446744073709551615 overflows int

[bradfitz]

Working as intended per the language spec: https://golang.org/ref/spec#Constants

https://play.golang.org/p/-TM6jBzFpV

See also: https://blog.golang.org/constants

[robpike]

This is just a minor confusing property of the constants defined in the math package. They are all untyped constants (see blog.golang.org/constants), so by default they promote to type int in a call to Println.

[odeke-em]

I too was once surprised by almost the same error message, some 2 years ago https://twitter.com/odeke_et/status/664360654875267073 but @mattsiegel educated me.