Merge pull request #1024 from CommunityToolkit/dev/better-analyzer-filtering

Improve filtering in semi-auto property analyzer

Author: Sergio0694

src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Analyzers/UseObservablePropertyOnSemiAutoPropertyAnalyzer.cs

@@ -110,8 +110,9 @@ public override void Initialize(AnalysisContext context)
                         continue;
                     }
 
-                    // We can safely ignore properties that already have [ObservableProperty]
-                    if (typeSymbol.HasAttributeWithType(observablePropertySymbol))
+                    // We can safely ignore properties that already have [ObservableProperty].
+                    // This is because in that case, the other analyzer will already emit an error.
+                    if (propertySymbol.HasAttributeWithType(observablePropertySymbol))
                     {
                         continue;
                     }

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

@@ -1381,6 +1381,28 @@ public string Name
         await CSharpAnalyzerWithLanguageVersionTest<UseObservablePropertyOnSemiAutoPropertyAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.Preview);
     }
 
+    [TestMethod]
+    public async Task UseObservablePropertyOnSemiAutoPropertyAnalyzer_ValidProperty_WithObservableProperty_DoesNotWarn()
+    {
+        const string source = """
+            using CommunityToolkit.Mvvm.ComponentModel;
+            
+            namespace MyApp;
+
+            public partial class SampleViewModel : ObservableObject
+            {
+                [ObservableProperty]
+                public string Name
+                {
+                    get => field;
+                    set => SetProperty(ref field, value);
+                }
+            }
+            """;
+
+        await CSharpAnalyzerWithLanguageVersionTest<UseObservablePropertyOnSemiAutoPropertyAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.Preview);
+    }
+
     [TestMethod]
     public async Task UseObservablePropertyOnSemiAutoPropertyAnalyzer_ValidProperty_Warns()
     {