Radar · Go · Archive · Week 38 · Sep 15 – 21, 2025

maphash: drop purego version and establish stronger runtime boundary

Nice to knowstdlib

What changed: The proposal is to hand off maintenance of a reflection-based implementation of the maphash package to the GopherJS project and drop the purego implementation from std.
Production impact: The source does not say.
Try it: Run go test ./... to see that the maphash package no longer imports reflect.
Source: github.com/golang/go/issues/74285

Understand it, then run it

The maphash package is used by Go to create hash values for map keys. In the past it had two versions: one that worked only on the standard Go runtime and another “purego” version that could run on other implementations like TinyGo or GopherJS. The purego version was slow and pulled in many other packages, making it hard for low‑level parts of the standard library to depend on maphash. The change removes that purego version and keeps only the runtime‑specific implementation, which is now the single source of truth for hashing map keys.

Run it now

Todaygo

// This program demonstrates the current maphash implementation.
// In Go 1.27.1 the purego version has been removed, so we use the
// runtime‑specific implementation directly. The program hashes a
// string and prints the resulting 64‑bit value.

package main

import (
	"fmt"
	"hash/maphash"
)

func main() {
	var h maphash.Hash
	h.WriteString("hello world")
	fmt.Printf("hash: %x\n", h.Sum64())
}

What it printed when we ran it on Go 1.27.1

hash: 914c36ec41c4095d

Run sends this program (for Solidity, the contract and its tests) to our own sandbox, where it is compiled and run once, with no network, and what it printed or the test report comes back here. Nothing is kept. Runs are counted per visitor for the day so everyone gets a turn; the details are on the legal page.

Written by gpt-oss-20b from the linked source · claims checked against the sources · archive, not individually reviewed