Add extension members for static extensions in generated enums (#154)

* Add initial support for checking for C#14

* Add support for extension enums

* Add Integration tests

Author: andrewlock

src/NetEscapades.EnumGenerators/EnumGenerator.cs

@@ -16,6 +16,12 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
         context.RegisterPostInitializationOutput(ctx => ctx.AddSource(
             "EnumExtensionsAttribute.g.cs", SourceText.From(SourceGenerationHelper.Attribute, Encoding.UTF8)));
 
+        var csharp14IsSupported = context.CompilationProvider
+            .Select((x,_) => x is CSharpCompilation
+            {
+                LanguageVersion: LanguageVersion.Preview or >= (LanguageVersion)1400 // C#14
+            });
+        
         IncrementalValuesProvider<EnumToGenerate> enumsToGenerate = context.SyntaxProvider
             .ForAttributeWithMetadataName(Attributes.EnumExtensionsAttribute,
                 predicate: static (node, _) => node is EnumDeclarationSyntax,
@@ -34,16 +40,16 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             .SelectMany(static (m, _) => m!.Value)
             .WithTrackingName(TrackingNames.InitialExternalExtraction);
 
-        context.RegisterSourceOutput(enumsToGenerate,
-            static (spc, enumToGenerate) => Execute(in enumToGenerate, spc));
+        context.RegisterSourceOutput(enumsToGenerate.Combine(csharp14IsSupported),
+            static (spc, enumToGenerate) => Execute(in enumToGenerate.Left, enumToGenerate.Right, spc));
 
-        context.RegisterSourceOutput(externalEnums,
-            static (spc, enumToGenerate) => Execute(in enumToGenerate, spc));
+        context.RegisterSourceOutput(externalEnums.Combine(csharp14IsSupported),
+            static (spc, enumToGenerate) => Execute(in enumToGenerate.Left, enumToGenerate.Right, spc));
     }
 
-    static void Execute(in EnumToGenerate enumToGenerate, SourceProductionContext context)
+    static void Execute(in EnumToGenerate enumToGenerate, bool csharp14IsSupported, SourceProductionContext context)
     {
-        var (result, filename) = SourceGenerationHelper.GenerateExtensionClass(in enumToGenerate);
+        var (result, filename) = SourceGenerationHelper.GenerateExtensionClass(in enumToGenerate, csharp14IsSupported);
         context.AddSource(filename, SourceText.From(result, Encoding.UTF8));
     }
 

src/NetEscapades.EnumGenerators/SourceGenerationHelper.cs

@@ -101,7 +101,7 @@ public class EnumExtensionsAttribute<T> : System.Attribute
 
         """;
 
-    public static (string Content, string HintName) GenerateExtensionClass(in EnumToGenerate enumToGenerate)
+    public static (string Content, string HintName) GenerateExtensionClass(in EnumToGenerate enumToGenerate, bool csharp14IsSupported)
     {
         var constantValues = new HashSet<object>();
 
@@ -343,6 +343,22 @@ public static
                         }
                 """);
 
+        // Use c#14 style extension members so can be accessed from root type
+        if (csharp14IsSupported)
+        {
+            sb.Append(
+                """
+
+
+                        // C#14 Extension member syntax
+                        extension(
+                """).Append(fullyQualifiedName).Append(
+                """
+                )
+                        {
+                """);
+        }
+
         sb.Append(
             """
 
@@ -1456,6 +1472,21 @@ public static string[] GetNames()
 
                         };
                     }
+            """);
+
+        // Close the extension everything block
+        if (csharp14IsSupported)
+        {
+            sb.Append(
+            """
+
+                    }
+            """);
+        }
+
+        sb.Append(
+            """
+
                 }
             #pragma warning restore CS0612 // Ignore usages of obsolete members or enums
             #pragma warning restore CS0618 // Ignore usages of obsolete members or enums

tests/Directory.Build.props

@@ -11,6 +11,7 @@
 
     <!-- Attempt workaround for https://github.com/dotnet/sdk/issues/37636 -->
     <SatelliteResourceLanguages>en</SatelliteResourceLanguages>
+    <LangVersion>Preview</LangVersion>
   </PropertyGroup>
   <ItemGroup>
     <!-- Ignore 2.1.0 advisories -->

tests/NetEscapades.EnumGenerators.IntegrationTests/EnumInFooExtensionEverythingTests.cs

@@ -0,0 +1,48 @@
+using System;
+using Foo;
+using Xunit;
+
+#if INTEGRATION_TESTS
+namespace NetEscapades.EnumGenerators.IntegrationTests;
+#elif NETSTANDARD_INTEGRATION_TESTS
+namespace NetEscapades.EnumGenerators.NetStandard.IntegrationTests;
+#elif INTERCEPTOR_TESTS
+namespace NetEscapades.EnumGenerators.Interceptors.IntegrationTests;
+#elif NUGET_ATTRS_INTEGRATION_TESTS
+namespace NetEscapades.EnumGenerators.Nuget.Attributes.IntegrationTests;
+#elif NUGET_INTEGRATION_TESTS
+namespace NetEscapades.EnumGenerators.Nuget.IntegrationTests;
+#elif NUGET_INTERCEPTOR_TESTS
+namespace NetEscapades.EnumGenerators.Nuget.Interceptors.IntegrationTests;
+#else
+#error Unknown integration tests
+#endif
+
+public class EnumInFooExtensionEverythingTests : EnumInFooExtensionsTests
+{
+    protected override string[] GetNames() => EnumInFoo.GetNames();
+    protected override EnumInFoo[] GetValues() => EnumInFoo.GetValues();
+    protected override int[] GetValuesAsUnderlyingType() => EnumInFoo.GetValuesAsUnderlyingType();
+    protected override int AsUnderlyingValue(EnumInFoo value) => value.AsUnderlyingType();
+
+    protected override string ToStringFast(EnumInFoo value) => value.ToStringFast();
+    protected override string ToStringFast(EnumInFoo value, bool withMetadata) => value.ToStringFast(withMetadata);
+    protected override bool IsDefined(EnumInFoo value) => EnumInFoo.IsDefined(value);
+    protected override bool IsDefined(string name, bool allowMatchingMetadataAttribute) => EnumInFoo.IsDefined(name, allowMatchingMetadataAttribute);
+#if READONLYSPAN
+    protected override bool IsDefined(in ReadOnlySpan<char> name, bool allowMatchingMetadataAttribute) => EnumInFoo.IsDefined(name, allowMatchingMetadataAttribute);
+#endif
+    protected override bool TryParse(string name, out EnumInFoo parsed, bool ignoreCase, bool allowMatchingMetadataAttribute)
+        => EnumInFoo.TryParse(name, out parsed, ignoreCase);
+#if READONLYSPAN
+    protected override bool TryParse(in ReadOnlySpan<char> name, out EnumInFoo parsed, bool ignoreCase, bool allowMatchingMetadataAttribute)
+        => EnumInFoo.TryParse(name, out parsed, ignoreCase);
+#endif
+
+    protected override EnumInFoo Parse(string name, bool ignoreCase, bool allowMatchingMetadataAttribute)
+        => EnumInFoo.Parse(name, ignoreCase);
+#if READONLYSPAN
+    protected override EnumInFoo Parse(in ReadOnlySpan<char> name, bool ignoreCase, bool allowMatchingMetadataAttribute)
+        => EnumInFoo.Parse(name, ignoreCase);
+#endif
+}

tests/NetEscapades.EnumGenerators.Tests/EnumGeneratorTests.cs

@@ -1,6 +1,7 @@
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using NetEscapades.EnumGenerators.Interceptors;
 using VerifyTests;
 using VerifyXunit;
@@ -55,6 +56,26 @@ public enum MyEnum
         return Verifier.Verify(output, Settings());
     }
 
+    [Fact]
+    public Task CanGenerateEnumExtensionsInGlobalNamespace_CSharp14()
+    {
+        const string input =
+            """
+            using NetEscapades.EnumGenerators;
+
+            [EnumExtensions]
+            public enum MyEnum
+            {
+                First,
+                Second,
+            }
+            """;
+        var (diagnostics, output) = TestHelpers.GetGeneratedOutput(Generators(), new(LanguageVersion.Preview, options: null!, input));
+
+        Assert.Empty(diagnostics);
+        return Verifier.Verify(output, Settings());
+    }
+
     [Fact]
     public Task CanGenerateEnumExtensionsInChildNamespace()
     {

tests/NetEscapades.EnumGenerators.Tests/NetEscapades.EnumGenerators.Tests.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.11.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.14.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
     <PackageReference Include="System.ComponentModel.Annotations" Version="5.0.0" Condition="'$(TargetFramework)' == 'net48'" />
     <PackageReference Include="Verify.Xunit" Version="14.3.0" />