adds rule use-errors-new (#1142)

Co-authored-by: chavacava <salvador.cavadini@gmail.com>

rule/use_errors_new.go

@@ -0,0 +1,60 @@
+package rule
+
+import (
+	"go/ast"
+
+	"github.com/mgechev/revive/lint"
+)
+
+// UseErrorsNewRule spots calls to fmt.Errorf that can be replaced by errors.New.
+type UseErrorsNewRule struct{}
+
+// Apply applies the rule to given file.
+func (*UseErrorsNewRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
+	var failures []lint.Failure
+
+	walker := lintFmtErrorf{
+		onFailure: func(failure lint.Failure) {
+			failures = append(failures, failure)
+		},
+	}
+
+	ast.Walk(walker, file.AST)
+
+	return failures
+}
+
+// Name returns the rule name.
+func (*UseErrorsNewRule) Name() string {
+	return "use-errors-new"
+}
+
+type lintFmtErrorf struct {
+	onFailure func(lint.Failure)
+}
+
+func (w lintFmtErrorf) Visit(n ast.Node) ast.Visitor {
+	funcCall, ok := n.(*ast.CallExpr)
+	if !ok {
+		return w // not a function call
+	}
+
+	isFmtErrorf := isPkgDot(funcCall.Fun, "fmt", "Errorf")
+	if !isFmtErrorf {
+		return w // not a call to fmt.Errorf
+	}
+
+	if len(funcCall.Args) > 1 {
+		return w // the use of fmt.Errorf is legit
+	}
+
+	// the call is of the form fmt.Errorf("...")
+	w.onFailure(lint.Failure{
+		Category:   "errors",
+		Node:       n,
+		Confidence: 1,
+		Failure:    "replace fmt.Errorf by errors.New",
+	})
+
+	return w
+}