Skip generating properties when there is a name collision

Author: Sergio0694

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

@@ -29,8 +29,8 @@ internal static class Execute
         /// </summary>
         /// <param name="fieldSymbol">The input <see cref="IFieldSymbol"/> instance to process.</param>
         /// <param name="diagnostics">The resulting diagnostics from the processing operation.</param>
-        /// <returns>The resulting <see cref="PropertyInfo"/> instance for <paramref name="fieldSymbol"/>.</returns>
-        public static PropertyInfo GetInfo(IFieldSymbol fieldSymbol, out ImmutableArray<Diagnostic> diagnostics)
+        /// <returns>The resulting <see cref="PropertyInfo"/> instance for <paramref name="fieldSymbol"/>, if successful.</returns>
+        public static PropertyInfo? TryGetInfo(IFieldSymbol fieldSymbol, out ImmutableArray<Diagnostic> diagnostics)
         {
             ImmutableArray<Diagnostic>.Builder builder = ImmutableArray.CreateBuilder<Diagnostic>();
 
@@ -54,6 +54,13 @@ public static PropertyInfo GetInfo(IFieldSymbol fieldSymbol, out ImmutableArray<
                     fieldSymbol,
                     fieldSymbol.ContainingType,
                     fieldSymbol.Name);
+
+                diagnostics = builder.ToImmutable();
+
+                // If the generated property would collide, skip generating it entirely. This makes sure that
+                // users only get the helpful diagnostic about the collsiion, and not the normal compiler error
+                // about a definition for "Property" already existing on the target type, which might be confusing.
+                return null;
             }
 
             ImmutableArray<string>.Builder propertyChangedNames = ImmutableArray.CreateBuilder<string>();

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.cs

@@ -44,14 +44,14 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
         context.FilterWithLanguageVersion(ref fieldSymbolsWithAttribute, LanguageVersion.CSharp8, UnsupportedCSharpLanguageVersionError);
 
         // Gather info for all annotated fields
-        IncrementalValuesProvider<(HierarchyInfo Hierarchy, Result<PropertyInfo> Info)> propertyInfoWithErrors =
+        IncrementalValuesProvider<(HierarchyInfo Hierarchy, Result<PropertyInfo?> Info)> propertyInfoWithErrors =
             fieldSymbolsWithAttribute
             .Select(static (item, _) =>
             {
                 HierarchyInfo hierarchy = HierarchyInfo.From(item.ContainingType);
-                PropertyInfo propertyInfo = Execute.GetInfo(item, out ImmutableArray<Diagnostic> diagnostics);
+                PropertyInfo? propertyInfo = Execute.TryGetInfo(item, out ImmutableArray<Diagnostic> diagnostics);
 
-                return (hierarchy, new Result<PropertyInfo>(propertyInfo, diagnostics));
+                return (hierarchy, new Result<PropertyInfo?>(propertyInfo, diagnostics));
             });
 
         // Output the diagnostics
@@ -60,7 +60,8 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
         // Get the filtered sequence to enable caching
         IncrementalValuesProvider<(HierarchyInfo Hierarchy, PropertyInfo Info)> propertyInfo =
             propertyInfoWithErrors
-            .Select(static (item, _) => (item.Hierarchy, item.Info.Value))
+            .Select(static (item, _) => (item.Hierarchy, Info: item.Info.Value))
+            .Where(static item => item.Info is not null)!
             .WithComparers(HierarchyInfo.Comparer.Default, PropertyInfo.Comparer.Default);
 
         // Split and group by containing type