Merge remote-tracking branch 'origin/master' into 1.8

Source/Tools/Flax.Build/Build/DotNet/Builder.DotNet.cs

@@ -247,7 +247,7 @@ namespace Flax.Build
             args.Add("/fullpaths");
             args.Add("/filealign:512");
 #if USE_NETCORE
-            args.Add("/langversion:11.0");
+            args.Add($"/langversion:{dotnetSdk.CSharpLanguageVersion}");
             args.Add(string.Format("/nullable:{0}", buildOptions.ScriptingAPI.CSharpNullableReferences.ToString().ToLowerInvariant()));
             if (buildOptions.ScriptingAPI.CSharpNullableReferences == CSharpNullableReferences.Disable)
                 args.Add("-nowarn:8632"); // The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

Source/Tools/Flax.Build/Build/DotNet/DotNetSdk.cs

@@ -161,6 +161,18 @@ namespace Flax.Build
         /// </summary>
         public readonly string RuntimeVersionName;
 
+        /// <summary>
+        /// Maximum supported C#-language version for the SDK.
+        /// </summary>
+        public string CSharpLanguageVersion => Version.Major switch
+        {
+            8 => "12.0",
+            7 => "11.0",
+            6 => "10.0",
+            5 => "9.0",
+            _ => "7.3",
+        };
+
         /// <summary>
         /// Initializes a new instance of the <see cref="DotNetSdk"/> class.
         /// </summary>