Resolve #39 Add OmitNullableDirective property to the CreateSyncVersi…

…on attribute

README.md

@@ -67,6 +67,20 @@ A list of changes applied to the new synchronized method:
 - Remove `CreateSyncVersionAttribute`
 - Update XML documentation
 
+#### Properties
+
+##### OmitNullableDirective
+
+This source generator detects language version during the compilation. By default it will generate `#nullable enable` directive if and only if the language version is 8 or above. Since it is [impossible](https://github.com/dotnet/roslyn/issues/49555) to reliably determine whether nullable context is turned on or not, `OmitNullableDirective` property is available to omit that directive from generating.
+
+```cs
+[Zomp.SyncMethodGenerator.CreateSyncVersion(OmitNullableDirective = true)]
+public async Task MethodAsync()
+{
+    string f = null;
+}
+```
+
 ### SYNC_ONLY symbol
 
 In case there is logic which should only be executed in the synchronized version of the method, wrap it in `SYNC_ONLY` #if directive.
@@ -123,7 +137,7 @@ Other than required packages to run `act` itself, GitHub Actions script installs
 
 To build the project using act follow these instructions:
 
-### Windows
+#### Windows
 
 Install [chocolatey](https://chocolatey.org/install) if missing.
 
@@ -141,7 +155,7 @@ In the project directory run:
 act -P windows-latest=-self-hosted --artifact-server-path /tmp/artifacts
 ```
 
-### Linux
+#### Linux
 
 Install act by following these [instructions](https://lindevs.com/install-act-on-ubuntu).
 

src/Zomp.SyncMethodGenerator/SourceGenerationHelper.cs

@@ -5,16 +5,20 @@
 /// </summary>
 public static class SourceGenerationHelper
 {
-    internal const string CreateSyncVersionAttributeSource = """
+    internal const string CreateSyncVersionAttributeSource = $$"""
 // <auto-generated/>
 namespace Zomp.SyncMethodGenerator
 {
     /// <summary>
     /// An attribute that can be used to automatically generate a synchronous version of an async method. Must be used in a partial class.
     /// </summary>
     [System.AttributeUsage(System.AttributeTargets.Method)]
-    internal class CreateSyncVersionAttribute : System.Attribute
+    internal class {{SyncMethodSourceGenerator.CreateSyncVersionAttribute}} : System.Attribute
     {
+        /// <summary>
+        /// Gets or sets a value indicating whether "#nullable enable" directive will be omitted from generated code. False by default.
+        /// </summary>
+        public bool {{SyncMethodSourceGenerator.OmitNullableDirective}} { get; set; }
     }
 }
 """;

src/Zomp.SyncMethodGenerator/SyncMethodSourceGenerator.cs

@@ -12,6 +12,8 @@ public class SyncMethodSourceGenerator : IIncrementalGenerator
     public const string CreateSyncVersionAttribute = "CreateSyncVersionAttribute";
     internal const string QualifiedCreateSyncVersionAttribute = $"{ThisAssembly.RootNamespace}.{CreateSyncVersionAttribute}";
 
+    internal const string OmitNullableDirective = "OmitNullableDirective";
+
     private static MethodToGenerate? last;
 
     /// <inheritdoc/>
@@ -117,16 +119,22 @@ private static (MethodToGenerate MethodToGenerate, string Path, string Content)
             return null;
         }
 
+        AttributeData syncMethodGeneratorAttributeData = null!;
+
         foreach (AttributeData attributeData in methodSymbol.GetAttributes())
         {
             if (!attribute.Equals(attributeData.AttributeClass, SymbolEqualityComparer.Default))
             {
                 continue;
             }
 
+            syncMethodGeneratorAttributeData = attributeData;
             break;
         }
 
+        var explicitDisableNullable = syncMethodGeneratorAttributeData.NamedArguments.FirstOrDefault(c => c.Key == OmitNullableDirective) is { Value.Value: true };
+        disableNullable |= explicitDisableNullable;
+
         var classes = ImmutableArray.CreateBuilder<ClassDeclaration>();
         SyntaxNode? node = methodDeclarationSyntax;
         while (node.Parent is not null)

tests/Generator.Tests/NullabilityTests.cs

@@ -17,6 +17,23 @@ public async Task DoNothingAsync(string l)
         await Task.CompletedTask;
     }
 }
+""".Verify(sourceType: SourceType.Full);
+
+    [Fact]
+    public Task NullableOmitExplicit() => """
+#nullable disable
+
+namespace Test;
+
+partial class MyClass
+{
+    [Obsolete]
+    [CreateSyncVersion(OmitNullableDirective = true)]
+    public async Task MethodAsync()
+    {
+        string f = null;
+    }
+}
 """.Verify(sourceType: SourceType.Full);
 
     [Fact]

tests/Generator.Tests/Snapshots/NullabilityTests.NullableOmitExplicit#Test.MyClass.MethodAsync.g.verified.cs

@@ -0,0 +1,11 @@
+//HintName: Test.MyClass.MethodAsync.g.cs
+// <auto-generated/>
+namespace Test;
+partial class MyClass
+{
+    [global::System.ObsoleteAttribute]
+    public void Method()
+    {
+        string f = null;
+    }
+}