Replace Location with value-equatable LocationInfo — fix incremental cache invalidation on Clone

DesignPatterns.SourceGenerators/Generators/CompositePartGenerator.cs

@@ -142,7 +142,7 @@ private static Result<CompositeRegistration> Transform(GeneratorAttributeSyntaxC
                 ImplementsContract(implementation, contract),
                 HasPublicParameterlessConstructor(implementation),
                 ImplementsBuildable(implementation, contract),
-                context.TargetNode.GetLocation()));
+                new LocationInfo(context.TargetNode.GetLocation())));
         }
 
         return Result<CompositeRegistration>.Empty;
@@ -202,7 +202,7 @@ private static void ReportDuplicateKeys(SourceProductionContext context, List<Co
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DuplicateKeyDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Key,
                     contractName));
             }
@@ -220,7 +220,7 @@ private static void ReportUnknownParentKeys(SourceProductionContext context, Lis
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 UnknownParentKeyDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ParentKey!,
                 contractName));
         }
@@ -235,7 +235,7 @@ private static void ReportCycles(SourceProductionContext context, List<Composite
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 CycleDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.Key,
                 contractName));
         }
@@ -247,7 +247,7 @@ private static void ReportContractMismatches(SourceProductionContext context, Li
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 ContractMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName,
                 registration.Contract.FullyQualifiedName));
         }
@@ -259,7 +259,7 @@ private static void ReportMissingConstructors(SourceProductionContext context, L
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingParameterlessConstructorDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName));
         }
     }
@@ -273,7 +273,7 @@ private static void ReportMissingBuildable(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingBuildableDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName,
                 contract.FullyQualifiedName));
         }
@@ -446,5 +446,5 @@ private sealed record CompositeRegistration(
         bool ImplementsContract,
         bool HasPublicParameterlessConstructor,
         bool ImplementsBuildable,
-        Location Location);
+        LocationInfo Location);
 }

DesignPatterns.SourceGenerators/Generators/DecoratorGenerator.cs

@@ -126,7 +126,7 @@ private static Result<DecoratorRegistration> Transform(GeneratorAttributeSyntaxC
                 ImplementsAsyncDecoratorInterface(decoratorType, serviceType),
                 HasValidAsyncSignature(decoratorType, serviceType),
                 HasPublicParameterlessConstructor(decoratorType),
-                context.TargetNode.GetLocation()));
+                new LocationInfo(context.TargetNode.GetLocation())));
         }
 
         return Result<DecoratorRegistration>.Empty;
@@ -186,7 +186,7 @@ private static void ReportValidationDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DuplicateOrderDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Order,
                     serviceName));
             }
@@ -196,7 +196,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 ContractMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.DecoratorName,
                 registration.Service.FullyQualifiedName));
         }
@@ -205,7 +205,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingDecoratorInterfaceDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.DecoratorName,
                 registration.Service.FullyQualifiedName));
         }
@@ -214,7 +214,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 AsyncSignatureMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.DecoratorName,
                 registration.Service.FullyQualifiedName));
         }
@@ -225,14 +225,14 @@ private static void ReportValidationDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DiNotResolvableDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.DecoratorName));
             }
             else
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     MissingParameterlessConstructorDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.DecoratorName));
             }
         }
@@ -398,5 +398,5 @@ private sealed record DecoratorRegistration(
         bool ImplementsAsyncDecoratorInterface,
         bool HasValidAsyncSignature,
         bool HasPublicParameterlessConstructor,
-        Location Location);
+        LocationInfo Location);
 }

DesignPatterns.SourceGenerators/Generators/GenerateSingletonGenerator.cs

@@ -63,7 +63,7 @@ private static Result<SingletonTargetInfo> GetTargetInfo(GeneratorAttributeSynta
             }
         }
 
-        var location = classDeclaration.GetLocation();
+        var location = new LocationInfo(classDeclaration.GetLocation());
         var className = symbol.Name;
         var isStatic = symbol.IsStatic;
         var typeKind = symbol.TypeKind;
@@ -110,7 +110,7 @@ private static void Execute(SourceProductionContext context, Result<SingletonTar
     }
 
     private sealed record SingletonTargetInfo(
-        Location Location,
+        LocationInfo Location,
         string ClassName,
         string? NamespaceName,
         bool ThreadSafe,

DesignPatterns.SourceGenerators/Generators/HandlerOrderGenerator.cs

@@ -61,21 +61,21 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
                 source.Right));
     }
 
-    private static List<HandlerRegistration> Transform(GeneratorAttributeSyntaxContext context, bool isGenericAttribute)
+    private static EquatableArray<HandlerRegistration> Transform(GeneratorAttributeSyntaxContext context, bool isGenericAttribute)
     {
         var result = new List<HandlerRegistration>();
 
         if (context.TargetSymbol is not INamedTypeSymbol handlerType)
         {
-            return result;
+            return new EquatableArray<HandlerRegistration>(result.ToArray());
         }
 
         if (context.Attributes.IsDefaultOrEmpty)
         {
-            return result;
+            return new EquatableArray<HandlerRegistration>(result.ToArray());
         }
 
-        var location = context.TargetNode.GetLocation();
+        var location = new LocationInfo(context.TargetNode.GetLocation());
         var handlerName = handlerType.Name;
         var handlerFullyQualifiedDisplayString = handlerType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
 
@@ -147,7 +147,7 @@ private static List<HandlerRegistration> Transform(GeneratorAttributeSyntaxConte
                 location));
         }
 
-        return result;
+        return new EquatableArray<HandlerRegistration>(result.ToArray());
     }
 
     private static void Execute(
@@ -218,7 +218,7 @@ private static void ReportValidationDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DuplicateOrderDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Order,
                     contextName));
             }
@@ -228,7 +228,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 HandlerContractMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.HandlerName,
                 registration.Context.FullyQualifiedName));
         }
@@ -237,7 +237,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingParameterlessConstructorDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.HandlerName));
         }
 
@@ -262,7 +262,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.HandlerOrderGuardMethodNotFound,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.HandlerName,
                     contextTypeDisplay));
@@ -273,7 +273,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.HandlerOrderGuardMethodNotStatic,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.HandlerName));
                 continue;
@@ -283,7 +283,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.HandlerOrderGuardMethodWrongSignature,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.HandlerName,
                     contextTypeDisplay));
@@ -346,5 +346,5 @@ private sealed record HandlerRegistration(
         bool ImplementsHandler,
         bool HasPublicParameterlessConstructor,
         GuardResolution Guard,
-        Location Location);
+        LocationInfo Location);
 }

DesignPatterns.SourceGenerators/Generators/LocationInfo.cs

@@ -0,0 +1,74 @@
+using System;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Text;
+
+namespace DesignPatterns.SourceGenerators.Generators;
+
+/// <summary>
+/// A value-equatable representation of a <see cref="Location"/>. Used in
+/// incremental generator models to ensure correct caching by the Roslyn
+/// incremental pipeline — <see cref="Location"/> uses reference equality,
+/// which breaks model value equality when <see cref="Compilation.Clone"/>
+/// creates new <see cref="Location"/> objects.
+/// </summary>
+internal readonly struct LocationInfo : IEquatable<LocationInfo>
+{
+    public string? FilePath { get; }
+    public TextSpan TextSpan { get; }
+    public LinePositionSpan LineSpan { get; }
+
+    public LocationInfo(Location? location)
+    {
+        if (location is null)
+        {
+            FilePath = null;
+            TextSpan = default;
+            LineSpan = default;
+            return;
+        }
+
+        var lineSpan = location.GetLineSpan();
+        FilePath = location.SourceTree?.FilePath ?? lineSpan.Path;
+        TextSpan = location.SourceSpan;
+        LineSpan = lineSpan.Span;
+    }
+
+    /// <summary>
+    /// Reconstructs a <see cref="Location"/> suitable for diagnostic reporting.
+    /// The returned location is an <see cref="ExternalFileLocation"/> that does
+    /// not reference a <see cref="SyntaxTree"/>, which is sufficient for
+    /// <see cref="Diagnostic.Create(DiagnosticDescriptor, Location, object[])"/>.
+    /// </summary>
+    public Location? ToLocation()
+    {
+        if (FilePath is null)
+        {
+            return null;
+        }
+
+        return Location.Create(FilePath, TextSpan, LineSpan);
+    }
+
+    public bool Equals(LocationInfo other)
+    {
+        return string.Equals(FilePath, other.FilePath, StringComparison.Ordinal)
+            && TextSpan == other.TextSpan
+            && LineSpan == other.LineSpan;
+    }
+
+    public override bool Equals(object? obj) => obj is LocationInfo other && Equals(other);
+
+    public override int GetHashCode()
+    {
+        unchecked
+        {
+            return (StringComparer.Ordinal.GetHashCode(FilePath ?? string.Empty) * 397)
+                ^ TextSpan.GetHashCode()
+                ^ LineSpan.GetHashCode();
+        }
+    }
+
+    public static bool operator ==(LocationInfo left, LocationInfo right) => left.Equals(right);
+
+    public static bool operator !=(LocationInfo left, LocationInfo right) => !left.Equals(right);
+}

DesignPatterns.SourceGenerators/Generators/RegisterEventHandlerGenerator.cs

@@ -33,7 +33,7 @@ internal sealed record EventHandlerRegistration(
     string HandlerFullyQualifiedDisplayString,
     bool ImplementsHandlerInterface,
     bool HasPublicParameterlessConstructor,
-    Location Location);
+    LocationInfo Location);
 
 /// <summary>
 /// Generates <c>{Event}EventHandlerRegistry</c> static classes for
@@ -122,7 +122,7 @@ private static List<EventHandlerRegistration> Transform(
                     : eventType.ContainingNamespace.ToDisplayString(),
                 eventType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat));
 
-            var location = context.TargetNode.GetLocation();
+            var location = new LocationInfo(context.TargetNode.GetLocation());
             result.Add(new EventHandlerRegistration(
                 eventInfo,
                 handler.Name,
@@ -152,7 +152,7 @@ private static void Execute(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.RegisterEventHandlerContractMismatch,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.HandlerName,
                 registration.Event.FullyQualifiedName));
         }
@@ -169,7 +169,7 @@ private static void Execute(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.RegisterEventHandlerDuplicateOnSameClass,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.HandlerName,
                     registration.Event.FullyQualifiedName));
             }