Disabled ValidateAllProperties/RegisterAll generators w/ <= 8.0

Author: Sergio0694

Microsoft.Toolkit.Mvvm.SourceGenerators/ComponentModel/ObservableValidatorValidateAllPropertiesGenerator.cs

@@ -42,6 +42,13 @@ public void Execute(GeneratorExecutionContext context)
                 return;
             }
 
+            // Validate the language version (this needs at least C# 8.0 due to static local functions being used).
+            // If a lower C# version is set, just skip the execution silently. The fallback path will be used just fine.
+            if (context.ParseOptions is not CSharpParseOptions { LanguageVersion: >= LanguageVersion.CSharp8 })
+            {
+                return;
+            }
+
             // Get the symbol for the required attributes
             INamedTypeSymbol
                 validationSymbol = context.Compilation.GetTypeByMetadataName("System.ComponentModel.DataAnnotations.ValidationAttribute")!,

Microsoft.Toolkit.Mvvm.SourceGenerators/Messaging/IMessengerRegisterAllGenerator.cs

@@ -39,6 +39,12 @@ public void Execute(GeneratorExecutionContext context)
                 return;
             }
 
+            // Like in the ObservableValidator.ValidateALlProperties generator, execution is skipped if C# >= 8.0 isn't available
+            if (context.ParseOptions is not CSharpParseOptions { LanguageVersion: >= LanguageVersion.CSharp8 })
+            {
+                return;
+            }
+
             // Get the symbol for the IRecipient<T> interface type
             INamedTypeSymbol iRecipientSymbol = context.Compilation.GetTypeByMetadataName("Microsoft.Toolkit.Mvvm.Messaging.IRecipient`1")!;