fix: use all modifiers for user method mapping

src/Riok.Mapperly/Descriptors/Mappings/MethodMapping.cs

@@ -7,7 +7,6 @@
 using Riok.Mapperly.Symbols;
 using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 using static Riok.Mapperly.Emit.Syntax.SyntaxFactoryHelper;
-using Accessibility = Microsoft.CodeAnalysis.Accessibility;
 
 namespace Riok.Mapperly.Descriptors.Mappings;
 
@@ -22,8 +21,16 @@ public abstract class MethodMapping : NewInstanceMapping
     private const int SourceParameterIndex = 0;
     private const int ReferenceHandlerParameterIndex = 1;
 
-    private readonly Accessibility _accessibility = Accessibility.Private;
+    private static readonly IEnumerable<SyntaxToken> _privateSyntaxToken = new[] { TrailingSpacedToken(SyntaxKind.PrivateKeyword) };
+
+    private static readonly IEnumerable<SyntaxToken> _privateStaticSyntaxToken = new[]
+    {
+        TrailingSpacedToken(SyntaxKind.PrivateKeyword),
+        TrailingSpacedToken(SyntaxKind.StaticKeyword),
+    };
+
     private readonly ITypeSymbol _returnType;
+    private readonly IMethodSymbol? _partialMethodDefinition;
 
     private string? _methodName;
 
@@ -44,15 +51,12 @@ ITypeSymbol targetType
     {
         SourceParameter = sourceParameter;
         IsExtensionMethod = method.IsExtensionMethod;
-        IsPartial = method.IsPartialDefinition;
         ReferenceHandlerParameter = referenceHandlerParameter;
-        _accessibility = method.DeclaredAccessibility;
+        _partialMethodDefinition = method;
         _methodName = method.Name;
         _returnType = method.ReturnType.UpgradeNullable();
     }
 
-    private bool IsPartial { get; }
-
     protected bool IsExtensionMethod { get; }
 
     private string MethodName => _methodName ?? throw new InvalidOperationException();
@@ -106,13 +110,14 @@ protected virtual ParameterListSyntax BuildParameterList() =>
 
     private IEnumerable<SyntaxToken> BuildModifiers(bool isStatic)
     {
-        yield return Accessibility(_accessibility);
-
-        if (isStatic)
-            yield return TrailingSpacedToken(SyntaxKind.StaticKeyword);
+        // if a syntax is referenced it is the implementation part of partial method definition
+        // then copy all modifiers otherwise only set private and optionally static
+        if (_partialMethodDefinition?.DeclaringSyntaxReferences.FirstOrDefault()?.GetSyntax() is MethodDeclarationSyntax syntax)
+        {
+            return syntax.Modifiers.Select(x => TrailingSpacedToken(x.Kind()));
+        }
 
-        if (IsPartial)
-            yield return TrailingSpacedToken(SyntaxKind.PartialKeyword);
+        return isStatic ? _privateStaticSyntaxToken : _privateSyntaxToken;
     }
 
     private void ReserveParameterNames(UniqueNameBuilder nameBuilder, ParameterListSyntax parameters)

src/Riok.Mapperly/Emit/Syntax/SyntaxFactoryHelper.cs

@@ -29,18 +29,6 @@ private SyntaxFactoryHelper(int indentation, string assemblyName)
 
     public SyntaxFactoryHelper RemoveIndentation() => new(Indentation - 1, _assemblyName);
 
-    public static SyntaxToken Accessibility(Accessibility accessibility)
-    {
-        return accessibility switch
-        {
-            Microsoft.CodeAnalysis.Accessibility.Private => TrailingSpacedToken(SyntaxKind.PrivateKeyword),
-            Microsoft.CodeAnalysis.Accessibility.Protected => TrailingSpacedToken(SyntaxKind.ProtectedKeyword),
-            Microsoft.CodeAnalysis.Accessibility.Internal => TrailingSpacedToken(SyntaxKind.InternalKeyword),
-            Microsoft.CodeAnalysis.Accessibility.Public => TrailingSpacedToken(SyntaxKind.PublicKeyword),
-            _ => throw new ArgumentOutOfRangeException(nameof(accessibility), accessibility, null)
-        };
-    }
-
     public static AssignmentExpressionSyntax Assignment(ExpressionSyntax target, ExpressionSyntax source)
     {
         return AssignmentExpression(SyntaxKind.SimpleAssignmentExpression, target, SpacedToken(SyntaxKind.EqualsToken), source);

test/Riok.Mapperly.IntegrationTests/DerivedMapperTest.cs

@@ -0,0 +1,44 @@
+using System.Threading.Tasks;
+using FluentAssertions;
+using Riok.Mapperly.IntegrationTests.Mapper;
+using VerifyXunit;
+using Xunit;
+
+namespace Riok.Mapperly.IntegrationTests
+{
+    [UsesVerify]
+    public class DerivedMapperTest : BaseMapperTest
+    {
+        [Fact]
+        public Task SnapshotGeneratedSourceBaseMapper()
+        {
+            var path = GetGeneratedMapperFilePath(nameof(BaseMapper));
+            return Verifier.VerifyFile(path);
+        }
+
+        [Fact]
+        public Task SnapshotGeneratedSourceDerivedMapper()
+        {
+            var path = GetGeneratedMapperFilePath(nameof(DerivedMapper));
+            return Verifier.VerifyFile(path);
+        }
+
+        [Fact]
+        public Task SnapshotGeneratedSourceDerivedMapper2()
+        {
+            var path = GetGeneratedMapperFilePath(nameof(DerivedMapper2));
+            return Verifier.VerifyFile(path);
+        }
+
+        [Fact]
+        public void RunMappingShouldWork()
+        {
+            new BaseMapper().IntToLong(10).Should().Be(10L);
+            new BaseMapper().IntToShort(10).Should().Be(10);
+            new DerivedMapper().IntToLong(10).Should().Be(10L);
+            new DerivedMapper().IntToShort(10).Should().Be(10);
+            new DerivedMapper2().IntToLong(10).Should().Be(10L);
+            new DerivedMapper2().IntToShort(10).Should().Be(10);
+        }
+    }
+}

test/Riok.Mapperly.IntegrationTests/Mapper/DerivedMapper.cs

@@ -0,0 +1,26 @@
+using Riok.Mapperly.Abstractions;
+
+namespace Riok.Mapperly.IntegrationTests.Mapper
+{
+    [Mapper]
+    public partial class BaseMapper
+    {
+        public virtual partial long IntToLong(int value);
+
+        public partial short IntToShort(int value);
+    }
+
+    [Mapper]
+    public partial class DerivedMapper : BaseMapper
+    {
+        public override partial long IntToLong(int value);
+    }
+
+    [Mapper]
+    public partial class DerivedMapper2 : BaseMapper
+    {
+        public sealed override partial long IntToLong(int value);
+
+        public new partial short IntToShort(int value);
+    }
+}

test/Riok.Mapperly.IntegrationTests/_snapshots/DerivedMapperTest.SnapshotGeneratedSourceBaseMapper.verified.cs

@@ -0,0 +1,17 @@
+// <auto-generated />
+#nullable enable
+namespace Riok.Mapperly.IntegrationTests.Mapper
+{
+    public partial class BaseMapper
+    {
+        public virtual partial long IntToLong(int value)
+        {
+            return (long)value;
+        }
+
+        public partial short IntToShort(int value)
+        {
+            return (short)value;
+        }
+    }
+}

test/Riok.Mapperly.IntegrationTests/_snapshots/DerivedMapperTest.SnapshotGeneratedSourceDerivedMapper.verified.cs

@@ -0,0 +1,12 @@
+// <auto-generated />
+#nullable enable
+namespace Riok.Mapperly.IntegrationTests.Mapper
+{
+    public partial class DerivedMapper
+    {
+        public override partial long IntToLong(int value)
+        {
+            return (long)value;
+        }
+    }
+}

test/Riok.Mapperly.IntegrationTests/_snapshots/DerivedMapperTest.SnapshotGeneratedSourceDerivedMapper2.verified.cs

@@ -0,0 +1,17 @@
+// <auto-generated />
+#nullable enable
+namespace Riok.Mapperly.IntegrationTests.Mapper
+{
+    public partial class DerivedMapper2
+    {
+        public sealed override partial long IntToLong(int value)
+        {
+            return (long)value;
+        }
+
+        public new partial short IntToShort(int value)
+        {
+            return (short)value;
+        }
+    }
+}

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

@@ -151,7 +151,7 @@ public void EnumToOtherEnumByNameIgnoreCaseShouldSwitch()
     public Task EnumToOtherEnumByNameWithoutOverlap()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapEnum(EnumMappingStrategy.ByName)] partial E2 ToE1(E1 source);",
+            "[MapEnum(EnumMappingStrategy.ByName)] private partial E2 ToE1(E1 source);",
             "enum E1 {A, B, C}",
             "enum E2 {D, E, F}"
         );

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

@@ -45,7 +45,7 @@ public void EnumerableToExistingCustomCollection()
     public Task MapToExistingCollectionShouldWork()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "partial void Map(List<A>? source, RepeatedField<B> target);",
+            "private partial void Map(List<A>? source, RepeatedField<B> target);",
             "class RepeatedField<T> : IList<T> { public void Add(T item) {} }",
             "class A { public string Value { get; set; } }",
             "class B { public string Value { get; set; } }"
@@ -69,7 +69,7 @@ public void MapToExistingCollectionWithUnmappableElementsShouldDiagnostic()
     public Task MapToExistingStackShouldWork()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "partial void Map(List<A>? source, Stack<B> target);",
+            "private partial void Map(List<A>? source, Stack<B> target);",
             "class A { public string Value { get; set; } }",
             "class B { public string Value { get; set; } }"
         );
@@ -81,7 +81,7 @@ public Task MapToExistingStackShouldWork()
     public Task MapToExistingQueueShouldWork()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "partial void Map(List<A>? source, Queue<B> target);",
+            "private partial void Map(List<A>? source, Queue<B> target);",
             "class A { public string Value { get; set; } }",
             "class B { public string Value { get; set; } }"
         );

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

@@ -8,10 +8,10 @@ public Task WithGenericSourceAndTarget()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
             """
-                partial TTarget Map<TSource, TTarget>(TSource source);
+                private partial TTarget Map<TSource, TTarget>(TSource source);
 
-                partial B MapToB(A source);
-                partial D MapToD(C source);
+                private partial B MapToB(A source);
+                private partial D MapToD(C source);
                 """,
             "record struct A(string Value);",
             "record struct B(string Value);",
@@ -435,10 +435,10 @@ public Task WithGenericSourceAndTargetAndEnabledReferenceHandling()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
             """
-                partial TTarget Map<TSource, TTarget>(TSource source);
+                private partial TTarget Map<TSource, TTarget>(TSource source);
 
-                partial B MapToB(A source);
-                partial D MapToD(C source);
+                private partial B MapToB(A source);
+                private partial D MapToD(C source);
                 """,
             TestSourceBuilderOptions.WithReferenceHandling,
             "record struct A(string Value);",
@@ -454,10 +454,10 @@ public Task WithGenericSourceAndTargetAndEnabledReferenceHandlingAndParameter()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
             """
-                partial TTarget Map<TSource, TTarget>(TSource source, [ReferenceHandler] IReferenceHandler refHandler);
+                private partial TTarget Map<TSource, TTarget>(TSource source, [ReferenceHandler] IReferenceHandler refHandler);
 
-                partial B MapToB(A source, [ReferenceHandler] IReferenceHandler refHandler);
-                partial D MapToD(C source, [ReferenceHandler] IReferenceHandler refHandler);
+                private partial B MapToB(A source, [ReferenceHandler] IReferenceHandler refHandler);
+                private partial D MapToD(C source, [ReferenceHandler] IReferenceHandler refHandler);
                 """,
             TestSourceBuilderOptions.WithReferenceHandling,
             "record struct A(string Value);",

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

@@ -137,7 +137,7 @@ public Task AssemblyAttributeShouldWork()
             [Mapper(EnumMappingStrategy = EnumMappingStrategy.ByName)]
             public partial class MyMapper
             {
-                partial E2 Map(E1 source);
+                private partial E2 Map(E1 source);
             }
 
             enum E1 { value1 }

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

@@ -442,7 +442,7 @@ public void ManualUnflattenedPropertyDeepNullablePath()
     public Task ManualUnflattenedPropertyNullablePathNoParameterlessCtorShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"MyValueId\", \"Value.Id\")] partial B Map(A source);",
+            "[MapProperty($\"MyValueId\", \"Value.Id\")] private partial B Map(A source);",
             "class A { public string MyValueId { get; set; } }",
             "class B { public C? Value { get; set; } }",
             "class C { public C(string arg) {} public string Id { get; set; } }"
@@ -455,7 +455,7 @@ public Task ManualUnflattenedPropertyNullablePathNoParameterlessCtorShouldDiagno
     public Task ManualUnflattenedPropertySourcePropertyNotFoundShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"MyValueIdXXX\", \"Value.Id\")] partial B Map(A source);",
+            "[MapProperty($\"MyValueIdXXX\", \"Value.Id\")] private partial B Map(A source);",
             "class A { public string MyValueId { get; set; } }",
             "class B { public C? Value { get; set; } }",
             "class C { public C(string arg) {} public string Id { get; set; } }"
@@ -468,7 +468,7 @@ public Task ManualUnflattenedPropertySourcePropertyNotFoundShouldDiagnostic()
     public Task ManualUnflattenedPropertyTargetPropertyPathWriteOnlyShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"MyValueId\", \"Value.Id\")] partial B Map(A source);",
+            "[MapProperty($\"MyValueId\", \"Value.Id\")] private partial B Map(A source);",
             "class A { public string MyValueId { get; set; } }",
             "class B { public C? Value { set; } }",
             "class C { public C(string arg) {} public string Id { get; set; } }"
@@ -481,7 +481,7 @@ public Task ManualUnflattenedPropertyTargetPropertyPathWriteOnlyShouldDiagnostic
     public Task ManualUnflattenedPropertyTargetPropertyNotFoundShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"MyValueId\", \"Value.IdXXX\")] partial B Map(A source);",
+            "[MapProperty($\"MyValueId\", \"Value.IdXXX\")] private partial B Map(A source);",
             "class A { public string MyValueId { get; set; } }",
             "class B { public C? Value { get; set; } }",
             "class C { public C(string arg) {} public string Id { get; set; } }"

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

@@ -254,7 +254,7 @@ public void InitOnlyPropertySourceNotFoundShouldDiagnostic()
     public Task InitOnlyPropertyWithMultipleConfigurationsShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"StringValue2\", \"StringValue\")] [MapProperty($\"StringValue3\", \"StringValue\")] partial B Map(A source);",
+            "[MapProperty($\"StringValue2\", \"StringValue\")] [MapProperty($\"StringValue3\", \"StringValue\")] private partial B Map(A source);",
             "class A { public string StringValue2 { get; init; } public string StringValue3 { get; init; } }",
             "class B { public string StringValue { get; init; } }"
         );
@@ -266,7 +266,7 @@ public Task InitOnlyPropertyWithMultipleConfigurationsShouldDiagnostic()
     public Task InitOnlyPropertyWithPathConfigurationsShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"NestedValue\", \"Nested.Value\")] partial B Map(A source);",
+            "[MapProperty($\"NestedValue\", \"Nested.Value\")] private partial B Map(A source);",
             "class A { public string NestedValue { get; init; } }",
             "class B { public C Nested { get; init; } }",
             "class C { public string Value { get; init; } }"
@@ -279,7 +279,7 @@ public Task InitOnlyPropertyWithPathConfigurationsShouldDiagnostic()
     public Task InitOnlyPropertyWithConfigurationNotFoundSourcePropertyShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty($\"StringValue2\", \"StringValue\")] partial B Map(A source);",
+            "[MapProperty($\"StringValue2\", \"StringValue\")] private partial B Map(A source);",
             "class A { public string StringValue { get; init; } }",
             "class B { public string StringValue { get; init; } }"
         );

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

@@ -199,7 +199,7 @@ public void WithPropertyNameMappingStrategyCaseInsensitive()
     public Task WithPropertyNameMappingStrategyCaseSensitive()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "partial B Map(A source);",
+            "private partial B Map(A source);",
             new TestSourceBuilderOptions { PropertyNameMappingStrategy = PropertyNameMappingStrategy.CaseSensitive },
             "class A { public string StringValue { get; set; } }",
             "class B { public string stringvalue { get; set; } }"
@@ -212,7 +212,7 @@ public Task WithPropertyNameMappingStrategyCaseSensitive()
     public Task WithManualMappedNotFoundTargetPropertyShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty(nameof(A.StringValue), nameof(B.StringValue9)] partial B Map(A source);",
+            "[MapProperty(nameof(A.StringValue), nameof(B.StringValue9)] private partial B Map(A source);",
             "class A { public string StringValue { get; set; } }",
             "class B { public string StringValue2 { get; set; } }"
         );
@@ -224,7 +224,7 @@ public Task WithManualMappedNotFoundTargetPropertyShouldDiagnostic()
     public Task WithManualMappedNotFoundSourcePropertyShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty(\"StringValue9\", nameof(B.StringValue2)] partial B Map(A source);",
+            "[MapProperty(\"StringValue9\", nameof(B.StringValue2)] private partial B Map(A source);",
             "class A { public string StringValue { get; set; } }",
             "class B { public string StringValue2 { get; set; } }"
         );
@@ -296,7 +296,7 @@ public Task WithManualNotFoundTargetPropertyShouldDiagnostic()
     public Task WithManualNotFoundSourcePropertyShouldDiagnostic()
     {
         var source = TestSourceBuilder.MapperWithBodyAndTypes(
-            "[MapProperty(\"not_found\", nameof(B.StringValue2))] partial B Map(A source);",
+            "[MapProperty(\"not_found\", nameof(B.StringValue2))] private partial B Map(A source);",
             "class A { public string StringValue { get; set; } }",
             "class B { public string StringValue2 { get; set; } }"
         );