Improve locations resolution for new analyzers

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

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Linq;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
@@ -76,7 +75,7 @@ public override void Initialize(AnalysisContext context)
                         typeSymbols.TryGetValue(attributeName, out INamedTypeSymbol? attributeSymbol) &&
                         SymbolEqualityComparer.Default.Equals(attributeClass, attributeSymbol))
                     {
-                        context.ReportDiagnostic(Diagnostic.Create(UnsupportedCSharpLanguageVersionError, context.Symbol.Locations.FirstOrDefault()));
+                        context.ReportDiagnostic(Diagnostic.Create(UnsupportedCSharpLanguageVersionError, context.Symbol.GetLocationFromAttributeDataOrDefault(attribute)));
 
                         // If we created a diagnostic for this symbol, we can stop. Even if there's multiple attributes, no need for repeated errors
                         return;

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

@@ -5,6 +5,7 @@
 #if !ROSLYN_4_11_0_OR_GREATER
 
 using System.Collections.Immutable;
+using System.Linq;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -44,11 +45,11 @@ public override void Initialize(AnalysisContext context)
                 }
 
                 // If the property has [ObservableProperty], emit an error in all cases
-                if (propertySymbol.TryGetAttributeWithType(observablePropertySymbol, out AttributeData? observablePropertyAttribute))
+                if (propertySymbol.HasAttributeWithType(observablePropertySymbol))
                 {
                     context.ReportDiagnostic(Diagnostic.Create(
                         UnsupportedRoslynVersionForObservablePartialPropertySupport,
-                        observablePropertyAttribute.GetLocation(),
+                        propertySymbol.Locations.FirstOrDefault(),
                         propertySymbol.ContainingType,
                         propertySymbol));
                 }

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

@@ -5,6 +5,7 @@
 #if ROSLYN_4_11_0_OR_GREATER
 
 using System.Collections.Immutable;
+using System.Linq;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -57,7 +58,7 @@ public override void Initialize(AnalysisContext context)
                 }
 
                 // Check that we are in fact using [ObservableProperty]
-                if (!fieldSymbol.TryGetAttributeWithType(observablePropertySymbol, out AttributeData? observablePropertyAttribute))
+                if (!fieldSymbol.HasAttributeWithType(observablePropertySymbol))
                 {
                     return;
                 }
@@ -74,7 +75,7 @@ public override void Initialize(AnalysisContext context)
                 // Emit the diagnostic for this field to suggest changing to a partial property instead
                 context.ReportDiagnostic(Diagnostic.Create(
                     UseObservablePropertyOnPartialProperty,
-                    observablePropertyAttribute.GetLocation(),
+                    fieldSymbol.Locations.FirstOrDefault(),
                     ImmutableDictionary.Create<string, string?>()
                         .Add(FieldReferenceForObservablePropertyFieldAnalyzer.FieldNameKey, fieldSymbol.Name)
                         .Add(FieldReferenceForObservablePropertyFieldAnalyzer.PropertyNameKey, ObservablePropertyGenerator.Execute.GetGeneratedPropertyName(fieldSymbol)),

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

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Linq;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -79,7 +78,7 @@ public override void Initialize(AnalysisContext context)
                     {
                         context.ReportDiagnostic(Diagnostic.Create(
                             GeneratorAttributeNamesToDiagnosticsMap[attributeClass.Name],
-                            context.Symbol.Locations.FirstOrDefault(),
+                            context.Symbol.GetLocationFromAttributeDataOrDefault(attribute),
                             context.Symbol));
                     }
                 }

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

@@ -65,7 +65,7 @@ public override void Initialize(AnalysisContext context)
                 {
                     context.ReportDiagnostic(Diagnostic.Create(
                         WinRTGeneratedBindableCustomPropertyWithBaseObservablePropertyOnField,
-                        generatedBindableCustomPropertyAttribute.GetLocation(),
+                        typeSymbol.GetLocationFromAttributeDataOrDefault(generatedBindableCustomPropertyAttribute),
                         typeSymbol,
                         fieldSymbol.ContainingType,
                         fieldSymbol.Name));
@@ -76,7 +76,7 @@ public override void Initialize(AnalysisContext context)
                 {
                     context.ReportDiagnostic(Diagnostic.Create(
                         WinRTGeneratedBindableCustomPropertyWithBaseRelayCommand,
-                        generatedBindableCustomPropertyAttribute.GetLocation(),
+                        typeSymbol.GetLocationFromAttributeDataOrDefault(generatedBindableCustomPropertyAttribute),
                         typeSymbol,
                         methodSymbol));
                 }

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

@@ -5,6 +5,7 @@
 #if ROSLYN_4_11_0_OR_GREATER
 
 using System.Collections.Immutable;
+using System.Linq;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -50,11 +51,11 @@ public override void Initialize(AnalysisContext context)
                 }
 
                 // Emit a diagnostic if the field is using the [ObservableProperty] attribute
-                if (fieldSymbol.TryGetAttributeWithType(observablePropertySymbol, out AttributeData? observablePropertyAttribute))
+                if (fieldSymbol.HasAttributeWithType(observablePropertySymbol))
                 {
                     context.ReportDiagnostic(Diagnostic.Create(
                         WinRTObservablePropertyOnFieldsIsNotAotCompatible,
-                        observablePropertyAttribute.GetLocation(),
+                        fieldSymbol.Locations.FirstOrDefault(),
                         ImmutableDictionary.Create<string, string?>()
                             .Add(FieldReferenceForObservablePropertyFieldAnalyzer.FieldNameKey, fieldSymbol.Name)
                             .Add(FieldReferenceForObservablePropertyFieldAnalyzer.PropertyNameKey, ObservablePropertyGenerator.Execute.GetGeneratedPropertyName(fieldSymbol)),

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

@@ -59,7 +59,7 @@ public override void Initialize(AnalysisContext context)
                 {
                     context.ReportDiagnostic(Diagnostic.Create(
                         WinRTRelayCommandIsNotGeneratedBindableCustomPropertyCompatible,
-                        relayCommandAttribute.GetLocation(),
+                        methodSymbol.GetLocationFromAttributeDataOrDefault(relayCommandAttribute),
                         methodSymbol));
                 }
             }, SymbolKind.Method);

src/CommunityToolkit.Mvvm.SourceGenerators/Extensions/ISymbolExtensions.cs

@@ -175,4 +175,31 @@ public static bool CanBeAccessedFrom(this ISymbol symbol, IAssemblySymbol assemb
             accessibility == Accessibility.Public ||
             accessibility == Accessibility.Internal && symbol.ContainingAssembly.GivesAccessTo(assembly);
     }
+
+    /// <summary>
+    /// Gets the location of a given symbol that is in the same syntax tree of a specified attribute, or the first one.
+    /// </summary>
+    /// <param name="symbol">The input <see cref="ISymbol"/> instance to check.</param>
+    /// <param name="attributeData">The target <see cref="AttributeData"/> instance.</param>
+    /// <returns>The best <see cref="Location"/> match.</returns>
+    public static Location? GetLocationFromAttributeDataOrDefault(this ISymbol symbol, AttributeData attributeData)
+    {
+        Location? firstLocation = null;
+
+        // Get the syntax tree where the attribute application is located. We use
+        // it to try to find the symbol location that belongs to the same file.
+        SyntaxTree? attributeTree = attributeData.ApplicationSyntaxReference?.SyntaxTree;
+
+        foreach (Location location in symbol.Locations)
+        {
+            if (location.SourceTree == attributeTree)
+            {
+                return location;
+            }
+
+            firstLocation ??= location;
+        }
+
+        return firstLocation;
+    }
 }

tests/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4001.UnitTests/Test_UnsupportedRoslynVersionForPartialPropertyAnalyzer.cs

@@ -21,8 +21,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0044:ObservableProperty|}]            
-                    public string Bar { get; set; }
+                    [ObservableProperty]            
+                    public string {|MVVMTK0044:Bar|} { get; set; }
                 }
             }
             """;

tests/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4110.UnitTests/Test_SourceGeneratorsDiagnostics.cs

@@ -78,8 +78,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0042:ObservableProperty|}]            
-                    private string name;
+                    [ObservableProperty]            
+                    private string {|MVVMTK0042:name|};
                 }
             }
             """;
@@ -371,8 +371,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0045:ObservableProperty|}]            
-                    private string name;
+                    [ObservableProperty]            
+                    private string {|MVVMTK0045:name|};
                 }
             }
             """;
@@ -415,8 +415,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0045:ObservableProperty|}]            
-                    private string name;
+                    [ObservableProperty]            
+                    private string {|MVVMTK0045:name|};
                 }
             }
             """;
@@ -437,8 +437,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0045:ObservableProperty|}]            
-                    private string name;
+                    [ObservableProperty]            
+                    private string {|MVVMTK0045:name|};
                 }
             }
             """;
@@ -459,8 +459,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0045:ObservableProperty|}]            
-                    private string name;
+                    [ObservableProperty]            
+                    private string {|MVVMTK0045:name|};
                 }
             }
 
@@ -486,8 +486,8 @@ namespace MyApp
             {
                 public partial class SampleViewModel : ObservableObject
                 {            
-                    [{|MVVMTK0045:ObservableProperty|}]            
-                    private string name;
+                    [ObservableProperty]            
+                    private string {|MVVMTK0045:name|};
                 }
             }
 
@@ -585,8 +585,8 @@ public async Task WinRTGeneratedBindableCustomPropertyWithBasesMemberAnalyzer_Ta
 
             namespace MyApp
             {
-                [{|MVVMTK0047:GeneratedBindableCustomProperty|}]
-                public partial class SampleViewModel : BaseViewModel
+                [GeneratedBindableCustomProperty]
+                public partial class {|MVVMTK0047:SampleViewModel|} : BaseViewModel
                 {                    
                 }
 
@@ -620,8 +620,8 @@ public async Task WinRTGeneratedBindableCustomPropertyWithBasesMemberAnalyzer_Ta
 
             namespace MyApp
             {
-                [{|MVVMTK0048:GeneratedBindableCustomProperty|}]
-                public partial class SampleViewModel : BaseViewModel
+                [GeneratedBindableCustomProperty]
+                public partial class {|MVVMTK0048:SampleViewModel|} : BaseViewModel
                 {                    
                 }