cmd/validate: support setting openapi3.CircularReferenceCounter (#815)

README.md

@@ -58,7 +58,7 @@ Be sure to check [OpenAPI Initiative](https://github.com/OAI)'s [great tooling l
 # Some recipes
 ## Validating an OpenAPI document
 ```shell
-go run github.com/getkin/kin-openapi/cmd/validate@latest [--defaults] [--examples] [--ext] [--patterns] -- <local YAML or JSON file>
+go run github.com/getkin/kin-openapi/cmd/validate@latest [--circular] [--defaults] [--examples] [--ext] [--patterns] -- <local YAML or JSON file>
 ```
 
 ## Loading OpenAPI document

cmd/validate/main.go

@@ -12,6 +12,11 @@ import (
 	"github.com/getkin/kin-openapi/openapi3"
 )
 
+var (
+	defaultCircular = openapi3.CircularReferenceCounter
+	circular        = flag.Int("circular", defaultCircular, "bump this (upper) limit when there's trouble with cyclic schema references")
+)
+
 var (
 	defaultDefaults = true
 	defaults        = flag.Bool("defaults", defaultDefaults, "when false, disables schemas' default field validation")
@@ -36,7 +41,7 @@ func main() {
 	flag.Parse()
 	filename := flag.Arg(0)
 	if len(flag.Args()) != 1 || filename == "" {
-		log.Fatalf("Usage: go run github.com/getkin/kin-openapi/cmd/validate@latest [--defaults] [--examples] [--ext] [--patterns] -- <local YAML or JSON file>\nGot: %+v\n", os.Args)
+		log.Fatalf("Usage: go run github.com/getkin/kin-openapi/cmd/validate@latest [--circular] [--defaults] [--examples] [--ext] [--patterns] -- <local YAML or JSON file>\nGot: %+v\n", os.Args)
 	}
 
 	data, err := os.ReadFile(filename)
@@ -54,6 +59,7 @@ func main() {
 
 	switch {
 	case vd.OpenAPI == "3" || strings.HasPrefix(vd.OpenAPI, "3."):
+		openapi3.CircularReferenceCounter = *circular
 		loader := openapi3.NewLoader()
 		loader.IsExternalRefsAllowed = *ext
 
@@ -78,6 +84,9 @@ func main() {
 		}
 
 	case vd.Swagger == "2" || strings.HasPrefix(vd.Swagger, "2."):
+		if *circular != defaultCircular {
+			log.Fatal("Flag --circular is only for OpenAPIv3")
+		}
 		if *defaults != defaultDefaults {
 			log.Fatal("Flag --defaults is only for OpenAPIv3")
 		}