Update analyzer for C# 14.0 language version support

Renamed RequiresCSharpLanguageVersionPreviewAnalyzer to RequiresCSharpLanguageVersion14OrPreviewAnalyzer and updated logic to check for C# 14.0 or preview language versions. Adjusted generator and unit tests to reference the new analyzer and updated version checks for compatibility with Roslyn 5.0.0 or greater.

Author: Sergio0694

src/CommunityToolkit.Mvvm.SourceGenerators/CommunityToolkit.Mvvm.SourceGenerators.projitems

@@ -57,7 +57,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\FieldWithOrphanedDependentObservablePropertyAttributesAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\FieldReferenceForObservablePropertyFieldAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\UnsupportedRoslynVersionForPartialPropertyAnalyzer.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\RequiresCSharpLanguageVersionPreviewAnalyzer.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\RequiresCSharpLanguageVersion14OrPreviewAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\InvalidPropertyLevelObservablePropertyAttributeAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\UseObservablePropertyOnPartialPropertyAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\UnsupportedCSharpLanguageVersionAnalyzer.cs" />

src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs

@@ -85,8 +85,10 @@ public static bool IsCandidateValidForCompilation(MemberDeclarationSyntax node,
             // check. When we add Roslyn 18.0 support, we can also update this check to check for at least C# 14.
             if (node is PropertyDeclarationSyntax)
             {
-#if ROSLYN_4_12_0_OR_GREATER
-                return semanticModel.Compilation.HasLanguageVersionGreaterThan(LanguageVersion.CSharp13) || semanticModel.Compilation.IsLanguageVersionPreview();
+#if ROSLYN_5_0_0_OR_GREATER
+                return semanticModel.Compilation.HasLanguageVersionAtLeastEqualTo(LanguageVersion.CSharp14);
+#elif ROSLYN_4_12_0_OR_GREATER
+                return semanticModel.Compilation.IsLanguageVersionPreview();
 #else
                 return false;
 #endif

src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Analyzers/RequiresCSharpLanguageVersionPreviewAnalyzer.cs renamed to src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Analyzers/RequiresCSharpLanguageVersion14OrPreviewAnalyzer.cs

@@ -18,7 +18,7 @@ namespace CommunityToolkit.Mvvm.SourceGenerators;
 /// A diagnostic analyzer that generates errors when a property using <c>[ObservableProperty]</c> on a partial property is in a project with the C# language version not set to 14.0 or 'preview'.
 /// </summary>
 [DiagnosticAnalyzer(LanguageNames.CSharp)]
-public sealed class RequiresCSharpLanguageVersionPreviewAnalyzer : DiagnosticAnalyzer
+public sealed class RequiresCSharpLanguageVersion14OrPreviewAnalyzer : DiagnosticAnalyzer
 {
     /// <inheritdoc/>
     public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = [CSharpLanguageVersionIsNot14OrPreviewForObservableProperty];
@@ -32,7 +32,11 @@ public override void Initialize(AnalysisContext context)
         context.RegisterCompilationStartAction(static context =>
         {
             // If the language version is set to preview or if we are set to at least C# 14.0, we'll never emit diagnostics
+#if ROSLYN_5_0_0_OR_GREATER
+            if (context.Compilation.HasLanguageVersionAtLeastEqualTo(LanguageVersion.CSharp14))
+#else
             if (context.Compilation.IsLanguageVersionPreview())
+#endif
             {
                 return;
             }

tests/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4120.UnitTests/Test_SourceGeneratorsDiagnostics.cs

@@ -28,7 +28,7 @@ public partial class SampleViewModel : ObservableObject
             }
             """;
 
-        await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<RequiresCSharpLanguageVersionPreviewAnalyzer>(source, LanguageVersion.CSharp12);
+        await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<RequiresCSharpLanguageVersion14OrPreviewAnalyzer>(source, LanguageVersion.CSharp12);
     }
 
     [TestMethod]
@@ -47,7 +47,7 @@ public partial class SampleViewModel : ObservableObject
             }
             """;
 
-        await CSharpAnalyzerWithLanguageVersionTest<RequiresCSharpLanguageVersionPreviewAnalyzer>.VerifyAnalyzerAsync(
+        await CSharpAnalyzerWithLanguageVersionTest<RequiresCSharpLanguageVersion14OrPreviewAnalyzer>.VerifyAnalyzerAsync(
             source,
             LanguageVersion.CSharp12,
 
@@ -73,7 +73,7 @@ public partial class SampleViewModel : ObservableObject
             }
             """;
 
-        await CSharpAnalyzerWithLanguageVersionTest<RequiresCSharpLanguageVersionPreviewAnalyzer>.VerifyAnalyzerAsync(
+        await CSharpAnalyzerWithLanguageVersionTest<RequiresCSharpLanguageVersion14OrPreviewAnalyzer>.VerifyAnalyzerAsync(
             source,
             LanguageVersion.CSharp13,
 
@@ -97,7 +97,7 @@ public partial class SampleViewModel : ObservableObject
             }
             """;
 
-        await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<RequiresCSharpLanguageVersionPreviewAnalyzer>(source, languageVersion: LanguageVersion.Preview);
+        await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<RequiresCSharpLanguageVersion14OrPreviewAnalyzer>(source, languageVersion: LanguageVersion.Preview);
     }
 
     [TestMethod]
@@ -116,7 +116,7 @@ public partial class SampleViewModel : ObservableObject
             }
             """;
 
-        await CSharpAnalyzerWithLanguageVersionTest<RequiresCSharpLanguageVersionPreviewAnalyzer>.VerifyAnalyzerAsync(
+        await CSharpAnalyzerWithLanguageVersionTest<RequiresCSharpLanguageVersion14OrPreviewAnalyzer>.VerifyAnalyzerAsync(
             source,
             LanguageVersion.Preview,