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package rule
import (
"go/ast"
"strings"
"github.com/mgechev/revive/lint"
)
// ModifiesValRecRule lints assignments to value method-receivers.
type ModifiesValRecRule struct{}
// Apply applies the rule to given file.
func (r *ModifiesValRecRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
var failures []lint.Failure
onFailure := func(failure lint.Failure) {
failures = append(failures, failure)
}
w := lintModifiesValRecRule{file: file, onFailure: onFailure}
file.Pkg.TypeCheck()
ast.Walk(w, file.AST)
return failures
}
// Name returns the rule name.
func (r *ModifiesValRecRule) Name() string {
return "modifies-value-receiver"
}
type lintModifiesValRecRule struct {
file *lint.File
onFailure func(lint.Failure)
}
func (w lintModifiesValRecRule) Visit(node ast.Node) ast.Visitor {
switch n := node.(type) {
case *ast.FuncDecl:
if n.Recv == nil {
return nil // skip, not a method
}
receiver := n.Recv.List[0]
if _, ok := receiver.Type.(*ast.StarExpr); ok {
return nil // skip, method with pointer receiver
}
if w.skipType(receiver.Type) {
return nil // skip, receiver is a map or array
}
if len(receiver.Names) < 1 {
return nil // skip, anonymous receiver
}
receiverName := receiver.Names[0].Name
if receiverName == "_" {
return nil // skip, anonymous receiver
}
fselect := func(n ast.Node) bool {
// look for assignments with the receiver in the right hand
asgmt, ok := n.(*ast.AssignStmt)
if !ok {
return false
}
for _, exp := range asgmt.Lhs {
switch e := exp.(type) {
case *ast.IndexExpr: // receiver...[] = ...
continue
case *ast.StarExpr: // *receiver = ...
continue
case *ast.SelectorExpr: // receiver.field = ...
name := w.getNameFromExpr(e.X)
if name == "" || name != receiverName {
continue
}
if w.skipType(ast.Expr(e.Sel)) {
continue
}
case *ast.Ident: // receiver := ...
if e.Name != receiverName {
continue
}
default:
continue
}
return true
}
return false
}
assignmentsToReceiver := pick(n.Body, fselect, nil)
for _, assignment := range assignmentsToReceiver {
w.onFailure(lint.Failure{
Node: assignment,
Confidence: 1,
Failure: "suspicious assignment to a by-value method receiver",
})
}
}
return w
}
func (w lintModifiesValRecRule) skipType(t ast.Expr) bool {
rt := w.file.Pkg.TypeOf(t)
if rt == nil {
return false
}
rt = rt.Underlying()
rtName := rt.String()
// skip when receiver is a map or array
return strings.HasPrefix(rtName, "[]") || strings.HasPrefix(rtName, "map[")
}
func (lintModifiesValRecRule) getNameFromExpr(ie ast.Expr) string {
ident, ok := ie.(*ast.Ident)
if !ok {
return ""
}
return ident.Name
}
|
