112 lines
2.3 KiB
Go
112 lines
2.3 KiB
Go
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package rule
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import (
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"fmt"
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"go/ast"
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"github.com/mgechev/revive/lint"
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)
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// RangeValInClosureRule lints given else constructs.
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type RangeValInClosureRule struct{}
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// Apply applies the rule to given file.
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func (r *RangeValInClosureRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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walker := rangeValInClosure{
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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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}
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ast.Walk(walker, file.AST)
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return failures
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}
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// Name returns the rule name.
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func (r *RangeValInClosureRule) Name() string {
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return "range-val-in-closure"
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}
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type rangeValInClosure struct {
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onFailure func(lint.Failure)
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}
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func (w rangeValInClosure) Visit(node ast.Node) ast.Visitor {
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// Find the variables updated by the loop statement.
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var vars []*ast.Ident
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addVar := func(expr ast.Expr) {
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if id, ok := expr.(*ast.Ident); ok {
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vars = append(vars, id)
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}
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}
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var body *ast.BlockStmt
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switch n := node.(type) {
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case *ast.RangeStmt:
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body = n.Body
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addVar(n.Key)
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addVar(n.Value)
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case *ast.ForStmt:
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body = n.Body
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switch post := n.Post.(type) {
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case *ast.AssignStmt:
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// e.g. for p = head; p != nil; p = p.next
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for _, lhs := range post.Lhs {
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addVar(lhs)
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}
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case *ast.IncDecStmt:
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// e.g. for i := 0; i < n; i++
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addVar(post.X)
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}
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}
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if vars == nil {
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return w
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}
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// Inspect a go or defer statement
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// if it's the last one in the loop body.
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// (We give up if there are following statements,
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// because it's hard to prove go isn't followed by wait,
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// or defer by return.)
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if len(body.List) == 0 {
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return w
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}
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var last *ast.CallExpr
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switch s := body.List[len(body.List)-1].(type) {
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case *ast.GoStmt:
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last = s.Call
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case *ast.DeferStmt:
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last = s.Call
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default:
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return w
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}
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lit, ok := last.Fun.(*ast.FuncLit)
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if !ok {
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return w
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}
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if lit.Type == nil {
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// Not referring to a variable (e.g. struct field name)
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return w
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}
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ast.Inspect(lit.Body, func(n ast.Node) bool {
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id, ok := n.(*ast.Ident)
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if !ok || id.Obj == nil {
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return true
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}
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for _, v := range vars {
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if v.Obj == id.Obj {
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w.onFailure(lint.Failure{
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Confidence: 1,
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Failure: fmt.Sprintf("loop variable %v captured by func literal", id.Name),
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Node: n,
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})
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}
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}
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return true
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})
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return w
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}
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