findgopher.go

package main

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"log"
)

func main() {
	fs := token.NewFileSet()
	f, err := parser.ParseFile(fs, "gopher.go", nil, 0)
	if err != nil {
		log.Fatal(err)
	}
	ast.Inspect(f, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.Ident:
			if n.Name == "gopher" {
				fmt.Println(fs.Position(n.Pos()))
			}
			// TODO: caseを追加する
		}
		return true
	})
}

gopher.go

package main

import "fmt"

type Gopher struct {
	gopher string `json:"gopher"`
}

func main() {
	const gopher = "GOPHER"
	gogopher := GOPHER()
	gogopher.gopher = gopher
	fmt.Println(gogopher)
}

func GOPHER() (gopher *Gopher) {
	gopher = &Gopher{
		gopher: "gopher",
	}
	return
}