Add denylist import (#17)

- As per https://github.com/go-gitea/gitea/pull/18222#issuecomment-1008386067

Reviewed-on: https://gitea.com/gitea/gitea-vet/pulls/17
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: Norwin <noerw@noreply.gitea.io>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-committed-by: Gusted <williamzijl7@hotmail.com>

checks/denylisted-imports.go

@@ -0,0 +1,36 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package checks
+
+import (
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var (
+	deniedImports   = []string{"io/ioutil"}
+	DenylistImports = &analysis.Analyzer{
+		Name: "denylist_imports",
+		Doc:  "check for denied imports",
+		Run:  runDenylistImports,
+	}
+)
+
+func runDenylistImports(pass *analysis.Pass) (interface{}, error) {
+	for _, file := range pass.Files {
+		for _, im := range file.Imports {
+			val := im.Path.Value
+			val = strings.TrimPrefix(val, `"`)
+			val = strings.TrimSuffix(val, `"`)
+			for _, deniedImport := range deniedImports {
+				if deniedImport == val {
+					pass.Reportf(im.Path.Pos(), `"`+deniedImport+"\" is not allowed to be imported")
+				}
+			}
+		}
+	}
+	return nil, nil
+}

main.go

@@ -12,6 +12,7 @@ import (
 
 func main() {
 	unitchecker.Main(
+		checks.DenylistImports,
 		checks.Imports,
 		checks.License,
 		checks.Migrations,