Custom marshalling does incorrect escaping of some control characters

[jandubois]

Here is a sample program that uses a custom marshaller for string that just call into the regular yaml.Marshall function, so I would expect identical results as if not using a custom marshaller at all:

package main

import (
	"fmt"
	"github.com/goccy/go-yaml"
)

type Sample struct {
	Field string `yaml:"field"`
}

func marshalString(s string) ([]byte, error) {
	return yaml.Marshal(s)
}

func main() {
	sample := Sample{Field: "#foo\a\b\f\v\n\tbar"}
	b, _ := yaml.Marshal(sample)
	fmt.Print(string(b))

	options := []yaml.EncodeOption{yaml.CustomMarshaler[string](marshalString)}
	b, _ = yaml.MarshalWithOptions(sample, options...)
	fmt.Print(string(b))
}

The results are:

field: "#foo\a\b\f\v\n\tbar"
field: "#foo\\a\b\f\v\n\\tbar"

So when the custom marshaller is used, some control character (\a and \t) are getting a double-escape.

Version Variables

Go version: 1.23.1
go-yaml's Version: 1.12.0

[jandubois]

This issue has been fixed by #538 and #562. 🙏