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refactor (rule/modifies-value-receiver): replace AST walker by iteration over declarations (#1165)
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chavacava
GitHub
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361c74464d
commit
a31d5afbcd
@ -12,16 +12,41 @@ import (
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type ModifiesValRecRule struct{}
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// Apply applies the rule to given file.
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func (*ModifiesValRecRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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func (r *ModifiesValRecRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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onFailure := func(failure lint.Failure) {
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failures = append(failures, failure)
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}
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w := lintModifiesValRecRule{file: file, onFailure: onFailure}
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file.Pkg.TypeCheck()
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ast.Walk(w, file.AST)
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for _, decl := range file.AST.Decls {
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funcDecl, ok := decl.(*ast.FuncDecl)
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isAMethod := ok && funcDecl.Recv != nil
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if !isAMethod {
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continue // skip, not a method
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}
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receiver := funcDecl.Recv.List[0]
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if r.mustSkip(receiver, file.Pkg) {
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continue
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}
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receiverName := receiver.Names[0].Name
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assignmentsToReceiver := r.getAssignmentsToReceiver(receiverName, funcDecl.Body)
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if len(assignmentsToReceiver) == 0 {
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continue // receiver is not modified
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}
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methodReturnsReceiver := len(r.findReturnReceiverStatements(receiverName, funcDecl.Body)) > 0
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if methodReturnsReceiver {
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continue // modification seems legit (see issue #1066)
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}
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for _, assignment := range assignmentsToReceiver {
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failures = append(failures, lint.Failure{
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Node: assignment,
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Confidence: 1,
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Failure: "suspicious assignment to a by-value method receiver",
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})
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}
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}
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return failures
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}
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@ -31,92 +56,8 @@ func (*ModifiesValRecRule) Name() string {
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return "modifies-value-receiver"
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}
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type lintModifiesValRecRule struct {
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file *lint.File
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onFailure func(lint.Failure)
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}
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func (w lintModifiesValRecRule) Visit(node ast.Node) ast.Visitor {
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switch n := node.(type) {
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case *ast.FuncDecl:
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if n.Recv == nil {
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return nil // skip, not a method
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}
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receiver := n.Recv.List[0]
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if _, ok := receiver.Type.(*ast.StarExpr); ok {
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return nil // skip, method with pointer receiver
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}
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if w.skipType(receiver.Type) {
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return nil // skip, receiver is a map or array
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}
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if len(receiver.Names) < 1 {
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return nil // skip, anonymous receiver
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}
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receiverName := receiver.Names[0].Name
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if receiverName == "_" {
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return nil // skip, anonymous receiver
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}
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receiverAssignmentFinder := func(n ast.Node) bool {
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// look for assignments with the receiver in the right hand
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assignment, ok := n.(*ast.AssignStmt)
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if !ok {
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return false
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}
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for _, exp := range assignment.Lhs {
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switch e := exp.(type) {
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case *ast.IndexExpr: // receiver...[] = ...
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continue
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case *ast.StarExpr: // *receiver = ...
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continue
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case *ast.SelectorExpr: // receiver.field = ...
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name := w.getNameFromExpr(e.X)
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if name == "" || name != receiverName {
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continue
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}
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case *ast.Ident: // receiver := ...
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if e.Name != receiverName {
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continue
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}
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default:
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continue
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}
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return true
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}
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return false
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}
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assignmentsToReceiver := pick(n.Body, receiverAssignmentFinder)
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if len(assignmentsToReceiver) == 0 {
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return nil // receiver is not modified
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}
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methodReturnsReceiver := len(w.findReturnReceiverStatements(receiverName, n.Body)) > 0
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if methodReturnsReceiver {
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return nil // modification seems legit (see issue #1066)
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}
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for _, assignment := range assignmentsToReceiver {
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w.onFailure(lint.Failure{
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Node: assignment,
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Confidence: 1,
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Failure: "suspicious assignment to a by-value method receiver",
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})
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}
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}
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return w
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}
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func (w lintModifiesValRecRule) skipType(t ast.Expr) bool {
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rt := w.file.Pkg.TypeOf(t)
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func (r *ModifiesValRecRule) skipType(t ast.Expr, pkg *lint.Package) bool {
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rt := pkg.TypeOf(t)
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if rt == nil {
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return false
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}
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@ -128,7 +69,7 @@ func (w lintModifiesValRecRule) skipType(t ast.Expr) bool {
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return strings.HasPrefix(rtName, "[]") || strings.HasPrefix(rtName, "map[")
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}
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func (lintModifiesValRecRule) getNameFromExpr(ie ast.Expr) string {
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func (*ModifiesValRecRule) getNameFromExpr(ie ast.Expr) string {
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ident, ok := ie.(*ast.Ident)
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if !ok {
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return ""
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@ -137,7 +78,7 @@ func (lintModifiesValRecRule) getNameFromExpr(ie ast.Expr) string {
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return ident.Name
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}
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func (w lintModifiesValRecRule) findReturnReceiverStatements(receiverName string, target ast.Node) []ast.Node {
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func (r *ModifiesValRecRule) findReturnReceiverStatements(receiverName string, target ast.Node) []ast.Node {
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finder := func(n ast.Node) bool {
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// look for returns with the receiver as value
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returnStatement, ok := n.(*ast.ReturnStmt)
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@ -148,7 +89,7 @@ func (w lintModifiesValRecRule) findReturnReceiverStatements(receiverName string
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for _, exp := range returnStatement.Results {
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switch e := exp.(type) {
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case *ast.SelectorExpr: // receiver.field = ...
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name := w.getNameFromExpr(e.X)
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name := r.getNameFromExpr(e.X)
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if name == "" || name != receiverName {
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continue
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}
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@ -160,7 +101,7 @@ func (w lintModifiesValRecRule) findReturnReceiverStatements(receiverName string
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if e.Op != token.AND {
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continue
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}
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name := w.getNameFromExpr(e.X)
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name := r.getNameFromExpr(e.X)
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if name == "" || name != receiverName {
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continue
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}
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@ -177,3 +118,60 @@ func (w lintModifiesValRecRule) findReturnReceiverStatements(receiverName string
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return pick(target, finder)
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}
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func (r *ModifiesValRecRule) mustSkip(receiver *ast.Field, pkg *lint.Package) bool {
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if _, ok := receiver.Type.(*ast.StarExpr); ok {
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return true // skip, method with pointer receiver
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}
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if len(receiver.Names) < 1 {
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return true // skip, anonymous receiver
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}
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receiverName := receiver.Names[0].Name
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if receiverName == "_" {
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return true // skip, anonymous receiver
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}
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if r.skipType(receiver.Type, pkg) {
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return true // skip, receiver is a map or array
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}
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return false
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}
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func (r *ModifiesValRecRule) getAssignmentsToReceiver(receiverName string, funcBody *ast.BlockStmt) []ast.Node {
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receiverAssignmentFinder := func(n ast.Node) bool {
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// look for assignments with the receiver in the right hand
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assignment, ok := n.(*ast.AssignStmt)
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if !ok {
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return false
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}
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for _, exp := range assignment.Lhs {
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switch e := exp.(type) {
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case *ast.IndexExpr: // receiver...[] = ...
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continue
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case *ast.StarExpr: // *receiver = ...
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continue
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case *ast.SelectorExpr: // receiver.field = ...
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name := r.getNameFromExpr(e.X)
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if name == "" || name != receiverName {
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continue
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}
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case *ast.Ident: // receiver := ...
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if e.Name != receiverName {
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continue
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}
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default:
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continue
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}
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return true
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}
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return false
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}
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return pick(funcBody, receiverAssignmentFinder)
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}
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