fix: prevent crash for delegate fields when deep mapping is enabled (#…

…1058)

src/Riok.Mapperly/Descriptors/MappingBuilders/MappingBuilder.cs

@@ -11,7 +11,7 @@ public class MappingBuilder(MappingCollection mappings)
     {
         NullableMappingBuilder.TryBuildMapping,
         DerivedTypeMappingBuilder.TryBuildMapping,
-        SpecialTypeMappingBuilder.TryBuildMapping,
+        ToObjectMappingBuilder.TryBuildMapping,
         DirectAssignmentMappingBuilder.TryBuildMapping,
         QueryableMappingBuilder.TryBuildMapping,
         DictionaryMappingBuilder.TryBuildMapping,

src/Riok.Mapperly/Descriptors/MappingBuilders/NewInstanceObjectMemberMappingBuilder.cs

@@ -13,6 +13,9 @@ public static class NewInstanceObjectMemberMappingBuilder
         if (ctx.Target.SpecialType != SpecialType.None || ctx.Source.SpecialType != SpecialType.None)
             return null;
 
+        if (ctx.Source.IsDelegate() || ctx.Target.IsDelegate())
+            return null;
+
         if (ctx.ObjectFactories.TryFindObjectFactory(ctx.Source, ctx.Target, out var objectFactory))
             return new NewInstanceObjectFactoryMemberMapping(
                 ctx.Source,

src/Riok.Mapperly/Descriptors/MappingBuilders/ToObjectMappingBuilder.cs

@@ -0,0 +1,29 @@
+using Microsoft.CodeAnalysis;
+using Riok.Mapperly.Abstractions;
+using Riok.Mapperly.Descriptors.Mappings;
+using Riok.Mapperly.Diagnostics;
+
+namespace Riok.Mapperly.Descriptors.MappingBuilders;
+
+public static class ToObjectMappingBuilder
+{
+    public static NewInstanceMapping? TryBuildMapping(MappingBuilderContext ctx)
+    {
+        if (!ctx.IsConversionEnabled(MappingConversionType.ExplicitCast))
+            return null;
+
+        if (ctx.Target.SpecialType != SpecialType.System_Object)
+            return null;
+
+        if (!ctx.MapperConfiguration.UseDeepCloning)
+            return new CastMapping(ctx.Source, ctx.Target);
+
+        if (ctx.Source.SpecialType == SpecialType.System_Object)
+        {
+            ctx.ReportDiagnostic(DiagnosticDescriptors.MappedObjectToObjectWithoutDeepClone, ctx.Source.Name, ctx.Target.Name);
+            return new DirectAssignmentMapping(ctx.Source);
+        }
+
+        return new CastMapping(ctx.Source, ctx.Target, ctx.FindOrBuildMapping(ctx.Source, ctx.Source));
+    }
+}

src/Riok.Mapperly/Helpers/SymbolExtensions.cs

@@ -22,13 +22,24 @@ internal static class SymbolExtensions
     internal static string FullyQualifiedIdentifierName(this ITypeSymbol typeSymbol) =>
         typeSymbol.ToDisplayString(_fullyQualifiedNullableFormat);
 
-    internal static bool IsImmutable(this ISymbol symbol) =>
-        symbol is INamedTypeSymbol namedSymbol
-        && (
-            namedSymbol.IsUnmanagedType
+    internal static bool IsImmutable(this ISymbol symbol)
+    {
+        if (symbol is not INamedTypeSymbol namedSymbol)
+            return false;
+
+        return namedSymbol.IsUnmanagedType
             || namedSymbol.SpecialType == SpecialType.System_String
-            || _wellKnownImmutableTypes.Contains(namedSymbol.ToDisplayString())
-        );
+            || IsDelegate(symbol)
+            || _wellKnownImmutableTypes.Contains(namedSymbol.ToDisplayString());
+    }
+
+    internal static bool IsDelegate(this ISymbol symbol)
+    {
+        if (symbol is not INamedTypeSymbol namedSymbol)
+            return false;
+
+        return namedSymbol.DelegateInvokeMethod != null;
+    }
 
     internal static int GetInheritanceLevel(this ITypeSymbol symbol)
     {

test/Riok.Mapperly.Tests/Mapping/DelegateTest.cs

@@ -0,0 +1,59 @@
+using Riok.Mapperly.Diagnostics;
+
+namespace Riok.Mapperly.Tests.Mapping;
+
+public class DelegateTest
+{
+    [Fact]
+    public void ActionToAction()
+    {
+        var source = TestSourceBuilder.Mapping("Action<string>", "Action<string>");
+        TestHelper.GenerateMapper(source).Should().HaveMapMethodBody("return source;");
+    }
+
+    [Fact]
+    public void ActionToActionWithDeepCloning()
+    {
+        var source = TestSourceBuilder.Mapping("Action<string>", "Action<string>", TestSourceBuilderOptions.WithDeepCloning);
+        TestHelper.GenerateMapper(source).Should().HaveMapMethodBody("return source;");
+    }
+
+    [Fact]
+    public void FuncToFunc()
+    {
+        var source = TestSourceBuilder.Mapping("Func<string, string>", "Func<string, string>");
+        TestHelper.GenerateMapper(source).Should().HaveMapMethodBody("return source;");
+    }
+
+    [Fact]
+    public void FuncToFuncWithDeepCloning()
+    {
+        var source = TestSourceBuilder.Mapping("Func<string>", "Func<string>", TestSourceBuilderOptions.WithDeepCloning);
+        TestHelper.GenerateMapper(source).Should().HaveMapMethodBody("return source;");
+    }
+
+    [Fact]
+    public void CustomDelegateToCustomDelegate()
+    {
+        var source = TestSourceBuilder.Mapping("X", "X", "delegate string X(string value);");
+        TestHelper.GenerateMapper(source).Should().HaveMapMethodBody("return source;");
+    }
+
+    [Fact]
+    public void CustomDelegateToCustomDelegateWithDeepCloning()
+    {
+        var source = TestSourceBuilder.Mapping("X", "X", TestSourceBuilderOptions.WithDeepCloning, "delegate string X(string value);");
+        TestHelper.GenerateMapper(source).Should().HaveMapMethodBody("return source;");
+    }
+
+    [Fact]
+    public void FuncToCustomDelegateShouldDiagnostic()
+    {
+        var source = TestSourceBuilder.Mapping("Func<string, string>", "X", "delegate string X(string value);");
+        TestHelper
+            .GenerateMapper(source, TestHelperOptions.AllowDiagnostics)
+            .Should()
+            .HaveDiagnostic(DiagnosticDescriptors.CouldNotCreateMapping)
+            .HaveAssertedAllDiagnostics();
+    }
+}

test/Riok.Mapperly.Tests/Mapping/SpecialTypeDeepCloningTest.cs → test/Riok.Mapperly.Tests/Mapping/ToObjectDeepCloningTest.cs

@@ -2,7 +2,7 @@
 
 namespace Riok.Mapperly.Tests.Mapping;
 
-public class SpecialTypeDeepCloningTest
+public class ToObjectDeepCloningTest
 {
     [Fact]
     public void ClassToObjectDeepCloning()

test/Riok.Mapperly.Tests/Mapping/SpecialTypeTest.cs → test/Riok.Mapperly.Tests/Mapping/ToObjectTypeTest.cs

@@ -1,6 +1,6 @@
 namespace Riok.Mapperly.Tests.Mapping;
 
-public class SpecialTypeTest
+public class ToObjectTypeTest
 {
     [Fact]
     public void ClassToObject()