Radar · Go · #001 · Week 39 · Sep 21 – 27, 2026

spec: remove string(int)

Worth knowinglanguage

What changed: Accepted: from language version 1.28, an integer can be converted to a string only if its type is byte or rune, or if it is an untyped rune constant such as 'A'. This lifts a check that go vet has made for years into the language itself.
Production impact: Code that converts other integer types with string(i) stops compiling once its module's go.mod says go 1.28 or later; go vet already reports these conversions today.
Try it: Run go vet ./... on your module: it reports each string(i) the new rule will reject.
Source: github.com/golang/go/issues/3939

Understand it, then run it

Converting an integer to a string with string(i) does not give you its digits. It gives you the character whose Unicode code point is i: string(65) is "A", not "65". This surprises almost everyone who meets it, which is why go vet has warned about it for years.

The accepted proposal makes the rule part of the language. From language version 1.28, string(i) compiles only when i is a byte or a rune, the two integer types that already mean "a character". If you want the digits, use strconv.Itoa(i).

Run it now

Todaygo

package main

import (
	"fmt"
	"strconv"
)

// Compiles on Go 1.27.1. string(i) with an int is the form the new rule
// removes from language version 1.28: it gives the character whose Unicode
// code point is i, never the digits of i.
func main() {
	for _, i := range []int{65, 0x1F600, -1} {
		fmt.Printf("i = %d\n", i)
		fmt.Printf("  string(i)        = %q\n", string(i))       // the form Go 1.28 removes
		fmt.Printf("  string(rune(i))  = %q\n", string(rune(i))) // the same character, said explicitly
		fmt.Printf("  strconv.Itoa(i)  = %q\n", strconv.Itoa(i)) // the digits, if that was meant
	}
}

What it printed when we ran it on Go 1.27.1

i = 65
  string(i)        = "A"
  string(rune(i))  = "A"
  strconv.Itoa(i)  = "65"
i = 128512
  string(i)        = "😀"
  string(rune(i))  = "😀"
  strconv.Itoa(i)  = "128512"
i = -1
  string(i)        = "�"
  string(rune(i))  = "�"
  strconv.Itoa(i)  = "-1"

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Written by gpt-oss-120b from the linked source · claims checked against the sources · human-reviewed