fix: enable static user methods for instance mappers (#364)

src/Riok.Mapperly/AnalyzerReleases.Shipped.md

@@ -79,3 +79,9 @@ RMG030  | Mapper   | Error    | Reference loop detected while mapping to an init
 RMG031  | Mapper   | Warning  | Reference loop detected while mapping to a constructor member
 RMG032  | Mapper   | Warning  | The enum mapping strategy ByName cannot be used in projection mappings
 RMG033  | Mapper   | Info     | Object mapped to another object without deep clone
+
+### Removed Rules
+
+Rule ID | Category | Severity | Notes
+--------|----------|----------|-------
+RMG019  | Mapper   | Disabled | Partial instance mapping method in a static mapper

src/Riok.Mapperly/Descriptors/UserMethodMappingExtractor.cs

@@ -67,7 +67,7 @@ bool isStatic
             BuildParameters(ctx, method, out var parameters)
             && !method.ReturnsVoid
             && (allowPartial || !method.IsPartialDefinition)
-            && isStatic == method.IsStatic;
+            && (!isStatic || method.IsStatic);
         return valid ? new UserImplementedMethodMapping(method, parameters.Source, parameters.ReferenceHandler) : null;
     }
 
@@ -76,15 +76,10 @@ bool isStatic
         if (!methodSymbol.IsPartialDefinition)
             return null;
 
-        if (isStatic != methodSymbol.IsStatic)
+        if (!isStatic && methodSymbol.IsStatic)
         {
-            ctx.ReportDiagnostic(
-                isStatic
-                    ? DiagnosticDescriptors.PartialInstanceMethodInStaticMapper
-                    : DiagnosticDescriptors.PartialStaticMethodInInstanceMapper,
-                methodSymbol,
-                methodSymbol.Name
-            );
+            ctx.ReportDiagnostic(DiagnosticDescriptors.PartialStaticMethodInInstanceMapper, methodSymbol, methodSymbol.Name);
+
             return null;
         }
 

src/Riok.Mapperly/Diagnostics/DiagnosticDescriptors.cs

@@ -168,15 +168,6 @@ internal static class DiagnosticDescriptors
         true
     );
 
-    public static readonly DiagnosticDescriptor PartialInstanceMethodInStaticMapper = new DiagnosticDescriptor(
-        "RMG019",
-        "Partial instance mapping method in a static mapper",
-        "{0} is a partial instance mapping method in a static mapper. Instance mapping methods are only supported in instance (non-static) mappers.",
-        DiagnosticCategories.Mapper,
-        DiagnosticSeverity.Error,
-        true
-    );
-
     public static readonly DiagnosticDescriptor SourceMemberNotMapped = new DiagnosticDescriptor(
         "RMG020",
         "Source member is not mapped to any target member",

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

@@ -13,7 +13,7 @@ public Task WithNamespaceShouldWork()
     }
 
     [Fact]
-    public Task StaticMapperShouldEmitDiagnosticForInstanceMethods()
+    public Task InstanceMapperShouldEmitDiagnosticForPartialStaticMethods()
     {
         var source =
             @"
@@ -22,9 +22,9 @@ public Task StaticMapperShouldEmitDiagnosticForInstanceMethods()
 using Riok.Mapperly.Abstractions;
 
 [Mapper]
-public static partial class MyStaticMapper
+public partial class MyMapper
 {
-    public partial static object StaticToObject(string s);
+    public static object StaticToObject(string s);
 
     public partial object InstanceToObject(string s);
 }
@@ -33,7 +33,7 @@ public static partial class MyStaticMapper
     }
 
     [Fact]
-    public Task InstanceMapperShouldEmitDiagnosticForStaticMethods()
+    public Task InstanceMapperShouldSupportUserDefinedStaticMethods()
     {
         var source =
             @"
@@ -44,10 +44,13 @@ public Task InstanceMapperShouldEmitDiagnosticForStaticMethods()
 [Mapper]
 public partial class MyMapper
 {
-    public partial static object StaticToObject(string s);
+    public static int StaticMapper(int s) => s;
 
-    public partial object InstanceToObject(string s);
+    public partial B Map(A s);
 }
+
+public record A(int Value);
+public record B(int Value);
 ";
         return TestHelper.VerifyGenerator(source);
     }

test/Riok.Mapperly.Tests/_snapshots/UserMethodTest.InstanceMapperShouldSupportUserDefinedStaticMethods#MyMapper.g.verified.cs

@@ -0,0 +1,10 @@
+//HintName: MyMapper.g.cs
+#nullable enable
+public partial class MyMapper
+{
+    public partial global::B Map(global::A s)
+    {
+        var target = new global::B(StaticMapper(s.Value));
+        return target;
+    }
+}