Go version

go version devel go1.23-5e1e3a0025 Thu Mar 21 17:25:54 2024 +0000 linux/amd64

What did you do?

Run this testscript script:

exec go generate ./...
-- go.mod --
module test
-- x_test.go --
package test

//go:generate stringer -type foo

type foo int

const (
	fooA foo = iota
	fooB
	fooC
)
-- x.go --
package test

What did you see happen?

> exec go generate ./...
[stderr]
stringer: no values defined for type foo
x_test.go:3: running "stringer": exit status 1

What did you expect to see?

I'd expect it to succeed and generate a file named foo_string_test.go containing a String method for the type foo.

It's sometimes useful to have the convenience of stringer to generate a String method even if the type is only defined for a test.