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varcheck.go
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varcheck.go
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// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"flag"
"fmt"
"go/ast"
"go/build"
"go/token"
"log"
"os"
"sort"
"strings"
"github.com/kisielk/gotool"
"golang.org/x/tools/go/loader"
"go/types"
)
var (
reportExported = flag.Bool("e", false, "Report exported variables and constants")
)
type object struct {
pkgPath string
name string
}
type visitor struct {
prog *loader.Program
pkg *loader.PackageInfo
uses map[object]int
positions map[object]token.Position
insideFunc bool
}
func getKey(obj types.Object) object {
if obj == nil {
return object{}
}
pkg := obj.Pkg()
pkgPath := ""
if pkg != nil {
pkgPath = pkg.Path()
}
return object{
pkgPath: pkgPath,
name: obj.Name(),
}
}
func (v *visitor) decl(obj types.Object) {
key := getKey(obj)
if _, ok := v.uses[key]; !ok {
v.uses[key] = 0
}
if _, ok := v.positions[key]; !ok {
v.positions[key] = v.prog.Fset.Position(obj.Pos())
}
}
func (v *visitor) use(obj types.Object) {
key := getKey(obj)
if _, ok := v.uses[key]; ok {
v.uses[key]++
} else {
v.uses[key] = 1
}
}
func isReserved(name string) bool {
return name == "_" || strings.HasPrefix(strings.ToLower(name), "_cgo_")
}
func (v *visitor) Visit(node ast.Node) ast.Visitor {
switch node := node.(type) {
case *ast.Ident:
v.use(v.pkg.Info.Uses[node])
case *ast.ValueSpec:
if !v.insideFunc {
for _, ident := range node.Names {
if !isReserved(ident.Name) {
v.decl(v.pkg.Info.Defs[ident])
}
}
}
for _, val := range node.Values {
ast.Walk(v, val)
}
return nil
case *ast.FuncDecl:
if node.Body != nil {
v.insideFunc = true
ast.Walk(v, node.Body)
v.insideFunc = false
}
return nil
}
return v
}
func main() {
flag.Parse()
exitStatus := 0
importPaths := gotool.ImportPaths(flag.Args())
if len(importPaths) == 0 {
importPaths = []string{"."}
}
ctx := build.Default
loadcfg := loader.Config{
Build: &ctx,
}
rest, err := loadcfg.FromArgs(importPaths, true)
if err != nil {
log.Fatalf("could not parse arguments: %s", err)
}
if len(rest) > 0 {
log.Fatalf("unhandled extra arguments: %v", rest)
}
program, err := loadcfg.Load()
if err != nil {
log.Fatalf("could not type check: %s", err)
}
uses := make(map[object]int)
positions := make(map[object]token.Position)
for _, pkgInfo := range program.InitialPackages() {
if pkgInfo.Pkg.Path() == "unsafe" {
continue
}
v := &visitor{
prog: program,
pkg: pkgInfo,
uses: uses,
positions: positions,
}
for _, f := range v.pkg.Files {
ast.Walk(v, f)
}
}
var lines []string
for obj, useCount := range uses {
if useCount == 0 && (*reportExported || !ast.IsExported(obj.name)) {
pos := positions[obj]
lines = append(lines, fmt.Sprintf("%s: %s:%d:%d: %s", obj.pkgPath, pos.Filename, pos.Line, pos.Column, obj.name))
exitStatus = 1
}
}
sort.Strings(lines)
for _, line := range lines {
fmt.Println(line)
}
os.Exit(exitStatus)
}