feat: add strict mapping

src/Riok.Mapperly.Abstractions/MapperAttribute.cs

@@ -86,4 +86,10 @@ public class MapperAttribute : Attribute
     /// Defaults to <see cref="IgnoreObsoleteMembersStrategy.None"/>.
     /// </summary>
     public IgnoreObsoleteMembersStrategy IgnoreObsoleteMembersStrategy { get; set; } = IgnoreObsoleteMembersStrategy.None;
+
+    /// <summary>
+    /// Defines the strategy used when emitting warnings for unmapped members.
+    /// By default this is <see cref="RequiredMappingStrategy.Both"/>, emitting warnings for unmapped source and target members.
+    /// </summary>
+    public RequiredMappingStrategy RequiredMappingStrategy { get; set; } = RequiredMappingStrategy.Both;
 }

src/Riok.Mapperly.Abstractions/MapperRequiredMappingAttribute.cs

@@ -0,0 +1,22 @@
+namespace Riok.Mapperly.Abstractions;
+
+/// <summary>
+/// Defines the strategy used when emitting warnings for unmapped members.
+/// </summary>
+[AttributeUsage(AttributeTargets.Method)]
+public sealed class MapperRequiredMappingAttribute : Attribute
+{
+    /// <summary>
+    /// Defines the strategy used when emitting warnings for unmapped members.
+    /// </summary>
+    /// <param name="requiredMappingStrategy">The strategy used when emitting warnings for unmapped members.</param>
+    public MapperRequiredMappingAttribute(RequiredMappingStrategy requiredMappingStrategy)
+    {
+        RequiredMappingStrategy = requiredMappingStrategy;
+    }
+
+    /// <summary>
+    /// The strategy used when emitting warnings for unmapped members.
+    /// </summary>
+    public RequiredMappingStrategy RequiredMappingStrategy { get; }
+}

src/Riok.Mapperly.Abstractions/PublicAPI.Shipped.txt

@@ -109,3 +109,13 @@ Riok.Mapperly.Abstractions.UseStaticMapperAttribute
 Riok.Mapperly.Abstractions.UseStaticMapperAttribute.UseStaticMapperAttribute(System.Type! mapperType) -> void
 Riok.Mapperly.Abstractions.UseStaticMapperAttribute<T>
 Riok.Mapperly.Abstractions.UseStaticMapperAttribute<T>.UseStaticMapperAttribute() -> void
+Riok.Mapperly.Abstractions.MapperAttribute.RequiredMappingStrategy.get -> Riok.Mapperly.Abstractions.RequiredMappingStrategy
+Riok.Mapperly.Abstractions.MapperAttribute.RequiredMappingStrategy.set -> void
+Riok.Mapperly.Abstractions.MapperRequiredMappingAttribute
+Riok.Mapperly.Abstractions.MapperRequiredMappingAttribute.MapperRequiredMappingAttribute(Riok.Mapperly.Abstractions.RequiredMappingStrategy requiredMappingStrategy) -> void
+Riok.Mapperly.Abstractions.MapperRequiredMappingAttribute.RequiredMappingStrategy.get -> Riok.Mapperly.Abstractions.RequiredMappingStrategy
+Riok.Mapperly.Abstractions.RequiredMappingStrategy
+Riok.Mapperly.Abstractions.RequiredMappingStrategy.Both = -1 -> Riok.Mapperly.Abstractions.RequiredMappingStrategy
+Riok.Mapperly.Abstractions.RequiredMappingStrategy.None = 0 -> Riok.Mapperly.Abstractions.RequiredMappingStrategy
+Riok.Mapperly.Abstractions.RequiredMappingStrategy.Source = 1 -> Riok.Mapperly.Abstractions.RequiredMappingStrategy
+Riok.Mapperly.Abstractions.RequiredMappingStrategy.Target = 2 -> Riok.Mapperly.Abstractions.RequiredMappingStrategy

src/Riok.Mapperly.Abstractions/RequiredMappingStrategy.cs

@@ -0,0 +1,28 @@
+namespace Riok.Mapperly.Abstractions;
+
+/// <summary>
+/// Defines the strategy used when emitting warnings for unmapped members.
+/// </summary>
+[Flags]
+public enum RequiredMappingStrategy
+{
+    /// <summary>
+    /// Warnings are not emitted for unmapped source or target members.
+    /// </summary>
+    None = 0,
+
+    /// <summary>
+    /// Warnings are emitted for both unmapped source and target members.
+    /// </summary>
+    Both = ~None,
+
+    /// <summary>
+    /// Warnings are emitted for unmapped source members but not for target members.
+    /// </summary>
+    Source = 1 << 0,
+
+    /// <summary>
+    /// Warnings are emitted for unmapped target members but not for source members.
+    /// </summary>
+    Target = 1 << 1
+}

src/Riok.Mapperly/Configuration/MapperConfiguration.cs

@@ -92,4 +92,10 @@ public record MapperConfiguration
     /// Defaults to <see cref="IgnoreObsoleteMembersStrategy.None"/>.
     /// </summary>
     public IgnoreObsoleteMembersStrategy? IgnoreObsoleteMembersStrategy { get; init; }
+
+    /// <summary>
+    /// Defines the strategy used when emitting warnings for unmapped members.
+    /// By default this is <see cref="RequiredMappingStrategy.Both"/>, emitting warnings for unmapped source and target members.
+    /// </summary>
+    public RequiredMappingStrategy? RequiredMappingStrategy { get; init; }
 }

src/Riok.Mapperly/Configuration/MapperConfigurationMerger.cs

@@ -46,6 +46,11 @@ public static MapperAttribute Merge(MapperConfiguration mapperConfiguration, Map
             ?? defaultMapperConfiguration.IgnoreObsoleteMembersStrategy
             ?? mapper.IgnoreObsoleteMembersStrategy;
 
+        mapper.RequiredMappingStrategy =
+            mapperConfiguration.RequiredMappingStrategy
+            ?? defaultMapperConfiguration.RequiredMappingStrategy
+            ?? mapper.RequiredMappingStrategy;
+
         return mapper;
     }
 }

src/Riok.Mapperly/Configuration/MapperConfigurationReader.cs

@@ -32,7 +32,8 @@ MapperConfiguration defaultMapperConfiguration
                 Array.Empty<string>(),
                 Array.Empty<string>(),
                 Array.Empty<PropertyMappingConfiguration>(),
-                Mapper.IgnoreObsoleteMembersStrategy
+                Mapper.IgnoreObsoleteMembersStrategy,
+                Mapper.RequiredMappingStrategy
             ),
             Array.Empty<DerivedTypeMappingConfiguration>()
         );
@@ -75,8 +76,17 @@ private PropertiesMappingConfiguration BuildPropertiesConfig(IMethodSymbol metho
         var ignoreObsolete = _dataAccessor.Access<MapperIgnoreObsoleteMembersAttribute>(method).FirstOrDefault() is not { } methodIgnore
             ? _defaultConfiguration.Properties.IgnoreObsoleteMembersStrategy
             : methodIgnore.IgnoreObsoleteStrategy;
+        var requiredMapping = _dataAccessor.Access<MapperRequiredMappingAttribute>(method).FirstOrDefault() is not { } methodWarnUnmapped
+            ? _defaultConfiguration.Properties.RequiredMappingStrategy
+            : methodWarnUnmapped.RequiredMappingStrategy;
 
-        return new PropertiesMappingConfiguration(ignoredSourceProperties, ignoredTargetProperties, explicitMappings, ignoreObsolete);
+        return new PropertiesMappingConfiguration(
+            ignoredSourceProperties,
+            ignoredTargetProperties,
+            explicitMappings,
+            ignoreObsolete,
+            requiredMapping
+        );
     }
 
     private EnumMappingConfiguration BuildEnumConfig(MappingConfigurationReference configRef)

src/Riok.Mapperly/Configuration/PropertiesMappingConfiguration.cs

@@ -6,5 +6,6 @@ public record PropertiesMappingConfiguration(
     IReadOnlyCollection<string> IgnoredSources,
     IReadOnlyCollection<string> IgnoredTargets,
     IReadOnlyCollection<PropertyMappingConfiguration> ExplicitMappings,
-    IgnoreObsoleteMembersStrategy IgnoreObsoleteMembersStrategy
+    IgnoreObsoleteMembersStrategy IgnoreObsoleteMembersStrategy,
+    RequiredMappingStrategy RequiredMappingStrategy
 );

src/Riok.Mapperly/Descriptors/MappingBodyBuilders/BuilderContext/MembersMappingBuilderContext.cs

@@ -166,6 +166,9 @@ private void AddUnmatchedTargetMembersDiagnostics()
 
     private void AddUnmatchedSourceMembersDiagnostics()
     {
+        if (!BuilderContext.Configuration.Properties.RequiredMappingStrategy.HasFlag(RequiredMappingStrategy.Source))
+            return;
+
         foreach (var sourceMemberName in _unmappedSourceMemberNames)
         {
             BuilderContext.ReportDiagnostic(

src/Riok.Mapperly/Descriptors/MappingBodyBuilders/NewInstanceObjectMemberMappingBodyBuilder.cs

@@ -59,12 +59,25 @@ out var sourceMemberPath
                 )
             )
             {
-                ctx.BuilderContext.ReportDiagnostic(
-                    targetMember.IsRequired ? DiagnosticDescriptors.RequiredMemberNotMapped : DiagnosticDescriptors.SourceMemberNotFound,
-                    targetMember.Name,
-                    ctx.Mapping.TargetType,
-                    ctx.Mapping.SourceType
-                );
+                if (targetMember.IsRequired)
+                {
+                    ctx.BuilderContext.ReportDiagnostic(
+                        DiagnosticDescriptors.RequiredMemberNotMapped,
+                        targetMember.Name,
+                        ctx.Mapping.TargetType,
+                        ctx.Mapping.SourceType
+                    );
+                }
+                else if (ctx.BuilderContext.Configuration.Properties.RequiredMappingStrategy.HasFlag(RequiredMappingStrategy.Target))
+                {
+                    ctx.BuilderContext.ReportDiagnostic(
+                        DiagnosticDescriptors.SourceMemberNotFound,
+                        targetMember.Name,
+                        ctx.Mapping.TargetType,
+                        ctx.Mapping.SourceType
+                    );
+                }
+
                 continue;
             }
 
@@ -104,12 +117,16 @@ IReadOnlyCollection<PropertyMappingConfiguration> memberConfigs
             !ctx.BuilderContext.SymbolAccessor.TryFindMemberPath(ctx.Mapping.SourceType, memberConfig.Source.Path, out var sourceMemberPath)
         )
         {
-            ctx.BuilderContext.ReportDiagnostic(
-                DiagnosticDescriptors.SourceMemberNotFound,
-                targetMember.Name,
-                ctx.Mapping.TargetType,
-                ctx.Mapping.SourceType
-            );
+            if (ctx.BuilderContext.Configuration.Properties.RequiredMappingStrategy.HasFlag(RequiredMappingStrategy.Target))
+            {
+                ctx.BuilderContext.ReportDiagnostic(
+                    DiagnosticDescriptors.SourceMemberNotFound,
+                    targetMember.Name,
+                    ctx.Mapping.TargetType,
+                    ctx.Mapping.SourceType
+                );
+            }
+
             return;
         }
 

src/Riok.Mapperly/Descriptors/MappingBodyBuilders/ObjectMemberMappingBodyBuilder.cs

@@ -54,7 +54,10 @@ out var sourceMemberPath
                 continue;
             }
 
-            if (targetMember.CanSet)
+            if (
+                targetMember.CanSet
+                && ctx.BuilderContext.Configuration.Properties.RequiredMappingStrategy.HasFlag(RequiredMappingStrategy.Target)
+            )
             {
                 ctx.BuilderContext.ReportDiagnostic(
                     DiagnosticDescriptors.SourceMemberNotFound,

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

@@ -30,6 +30,7 @@ public static partial class StaticTestMapper
         [MapperIgnoreSource(nameof(TestObject.IgnoredIntValue))]
         [MapperIgnoreTarget(nameof(TestObjectDto.IgnoredStringValue))]
         [MapperIgnoreObsoleteMembers]
+        [MapperRequiredMapping(RequiredMappingStrategy.Target)]
         public static partial TestObjectDto MapToDtoExt(this TestObject src);
 
         public static TestObjectDto MapToDto(TestObject src)

test/Riok.Mapperly.IntegrationTests/Models/TestObject.cs

@@ -26,6 +26,8 @@ public TestObject(int ctorValue, int unknownValue = 10, int ctorValue2 = 100)
         public int RequiredValue { get; init; }
 #endif
 
+        public int UnmappedValue => 10;
+
         public string StringValue { get; set; } = string.Empty;
 
         public string RenamedStringValue { get; set; } = string.Empty;

test/Riok.Mapperly.IntegrationTests/_snapshots/DeepCloningMapperTest.RunMappingShouldWork_NET6_0.verified.txt

@@ -4,6 +4,7 @@
   IntValue: 10,
   IntInitOnlyValue: 3,
   RequiredValue: 4,
+  UnmappedValue: 10,
   StringValue: fooBar,
   RenamedStringValue: fooBar2,
   Flattening: {
@@ -27,6 +28,7 @@
     CtorValue: 5,
     CtorValue2: 100,
     RequiredValue: 4,
+    UnmappedValue: 10,
     StringValue: ,
     RenamedStringValue: ,
     Flattening: {},
@@ -45,6 +47,7 @@
     CtorValue2: 100,
     IntValue: 99,
     RequiredValue: 98,
+    UnmappedValue: 10,
     StringValue: ,
     RenamedStringValue: ,
     Flattening: {},

test/Riok.Mapperly.IntegrationTests/_snapshots/MapperTest.RunMappingShouldWork_NET6_0.verified.txt

@@ -54,6 +54,7 @@
     CtorValue2: 100,
     IntValue: 99,
     RequiredValue: 98,
+    UnmappedValue: 10,
     StringValue: ,
     RenamedStringValue: ,
     Flattening: {},

test/Riok.Mapperly.IntegrationTests/_snapshots/StaticMapperTest.RunExtensionMappingShouldWork_NET6_0.verified.txt

@@ -49,6 +49,7 @@
     CtorValue2: 100,
     IntValue: 99,
     RequiredValue: 98,
+    UnmappedValue: 10,
     StringValue: ,
     RenamedStringValue: ,
     Flattening: {},

test/Riok.Mapperly.IntegrationTests/_snapshots/StaticMapperTest.RunMappingShouldWork_NET6_0.verified.txt

@@ -54,6 +54,7 @@
     CtorValue2: 100,
     IntValue: 99,
     RequiredValue: 98,
+    UnmappedValue: 10,
     StringValue: ,
     RenamedStringValue: ,
     Flattening: {},

test/Riok.Mapperly.Tests/Helpers/MapperConfigurationBuilderTest.cs

@@ -21,6 +21,7 @@ public void ShouldMergeMapperConfigurations()
             EnabledConversions = MappingConversionType.Dictionary,
             UseReferenceHandling = false,
             IgnoreObsoleteMembersStrategy = IgnoreObsoleteMembersStrategy.Target,
+            RequiredMappingStrategy = RequiredMappingStrategy.Target,
         };
 
         var mapper = MapperConfigurationMerger.Merge(mapperConfiguration, defaultMapperConfiguration);
@@ -34,6 +35,7 @@ public void ShouldMergeMapperConfigurations()
         mapper.EnabledConversions.Should().Be(MappingConversionType.Constructor);
         mapper.UseReferenceHandling.Should().BeTrue();
         mapper.IgnoreObsoleteMembersStrategy.Should().Be(IgnoreObsoleteMembersStrategy.Source);
+        mapper.RequiredMappingStrategy.Should().Be(RequiredMappingStrategy.Source);
     }
 
     [Fact]
@@ -51,6 +53,7 @@ public void ShouldMergeMapperConfigurationsWithEmptyDefaultMapperConfiguration()
         mapper.EnabledConversions.Should().Be(MappingConversionType.Constructor);
         mapper.UseReferenceHandling.Should().BeTrue();
         mapper.IgnoreObsoleteMembersStrategy.Should().Be(IgnoreObsoleteMembersStrategy.Source);
+        mapper.RequiredMappingStrategy.Should().Be(RequiredMappingStrategy.Source);
     }
 
     [Fact]
@@ -84,6 +87,7 @@ private MapperConfiguration NewMapperConfiguration()
             EnabledConversions = MappingConversionType.Constructor,
             UseReferenceHandling = true,
             IgnoreObsoleteMembersStrategy = IgnoreObsoleteMembersStrategy.Source,
+            RequiredMappingStrategy = RequiredMappingStrategy.Source,
         };
     }
 }