gosrcfmt

package main

import (
	"go/parser"
	"go/token"
	"io/ioutil"
	"os"

	"github.com/sirkon/message"

	"github.com/sirkon/gosrcfmt"
)

func main() {
	fset := token.NewFileSet()
	data, err := ioutil.ReadFile("testdata/main.go")
	if err != nil {
		message.Fatal(err)
	}
	file, err := parser.ParseFile(fset, "testdata/main.go", data, parser.AllErrors|parser.ParseComments)
	if err != nil {
		message.Fatal(err)
	}
	output, err := gosrcfmt.AST(fset, file)
	if err != nil {
		message.Fatal(err)
	}
	_, _ = os.Stdout.Write(output)

}

Output:

// +build !windows

package pkg

func main() {
	if true {
	}
}