Prevent infinite recursion. Fixes #1017

Author: commonsensesoftware

src/AspNetCore/WebApi/src/Asp.Versioning.Http/ApiVersioningFeature.cs

@@ -34,11 +34,7 @@ public IReadOnlyList<string> RawRequestedApiVersions
         {
             if ( rawApiVersions is null )
             {
-                var reader = context.RequestServices.GetService<IApiVersionReader>()
-                             ?? ApiVersionReader.Combine(
-                                 new QueryStringApiVersionReader(),
-                                 new UrlSegmentApiVersionReader() );
-
+                var reader = context.RequestServices.GetService<IApiVersionReader>() ?? ApiVersionReader.Default;
                 rawApiVersions = reader.Read( context.Request );
             }
 

src/Common/src/Common/ApiVersionReader.cs

@@ -16,6 +16,14 @@ namespace Asp.Versioning;
 #endif
 public static class ApiVersionReader
 {
+    private static IApiVersionReader? @default;
+
+    /// <summary>
+    /// Gets the default API version reader.
+    /// </summary>
+    /// <value>The default <see cref="IApiVersionReader"/>.</value>
+    public static IApiVersionReader Default => @default ??= Combine( new QueryStringApiVersionReader(), new UrlSegmentApiVersionReader() );
+
     /// <summary>
     /// Returns a new API version reader that is a combination of the specified set.
     /// </summary>

src/Common/src/Common/ApiVersioningOptions.cs

@@ -6,7 +6,6 @@ namespace Asp.Versioning;
 #if NETFRAMEWORK
 using System.Net;
 #endif
-using static Asp.Versioning.ApiVersionReader;
 
 /// <summary>
 /// Represents the possible options for API versioning.
@@ -73,7 +72,7 @@ public partial class ApiVersioningOptions
 #endif
     public IApiVersionReader ApiVersionReader
     {
-        get => apiVersionReader ??= Combine( new QueryStringApiVersionReader(), new UrlSegmentApiVersionReader() );
+        get => apiVersionReader ??= Versioning.ApiVersionReader.Default;
         set => apiVersionReader = value;
     }