Radar · Go · Archive · Week 22 · May 26 – Jun 1, 2025
cmd/fix: automate migrations for simple deprecations
Worth knowingtooling
- What changed
- The
go fixsubcommand can now automatically rewrite trivial API changes such as replacing a function call or constant with another. - Production impact
- The source does not say.
- Try it
- Run
go fix ./...on a module that contains a deprecated API to see if the tool updates the code. - Source
- github.com/golang/go/issues/32816
Understand it, then run it
Run it now
Todaygo
// This program demonstrates the new go:fix directives.
// It will not compile until the change ships in a future Go release.
// The comments below describe how go:fix would rewrite the code.
package main
import "fmt"
// Deprecated: Use io.SeekStart instead.
//go:fix-to io.SeekStart
const SEEK_SET int = 0
func main() {
// Before go:fix, this would use the old constant name.
// After go:fix, the line below would be rewritten to use io.SeekStart.
fmt.Println(SEEK_SET)
}
What it printed when we ran it on Go 1.27.1
0
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