Dump a Go source file as an Abstract Syntax Tree (AST)

main.go

package main

import (
	"fmt"
	"os"

	"go/ast"
	"go/format"
	"go/parser"
	"go/token"

	//"github.com/davecgh/go-spew/spew"
)

func main() {

	// positions are relative to fset
    fset := token.NewFileSet()

    // Read in the original file
	snippet, err := parser.ParseFile(fset, "original.go", nil, parser.Trace | parser.ParseComments)

	// Print structure to stdout
	ast.Print(fset, snippet)

	// Write to a final file for comparison
	f, err := os.Create("demo.txt")
	if err != nil {
		fmt.Println(err)
		os.Exit(-1)
	}

	defer f.Close()

	err = format.Node(f, fset, snippet)
	if err != nil {
		fmt.Println(err)
		os.Exit(-1)
	}
}

original.go

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.
// This is a generated file. Please do not make manual changes.

package main

func DemoFunc() (this *int, that *int) {
	return nil, nil
}