From b8b9e2a013200dad884de2a36976771f76428d67 Mon Sep 17 00:00:00 2001
From: Lars <lars@riok.ch>
Date: Mon, 26 Feb 2024 18:48:26 +0700
Subject: [PATCH] feat: report a diagnostic for invalid MapPropertyAttribute
 usages (#1130)

---
 src/Riok.Mapperly/AnalyzerReleases.Shipped.md |  1 +
 .../MapperConfigurationReader.cs              |  5 +++++
 .../MemberMappingConfiguration.cs             |  2 ++
 .../Diagnostics/DiagnosticDescriptors.cs      |  9 ++++++++
 .../Mapping/ObjectPropertyTest.cs             | 21 +++++++++++++++++++
 5 files changed, 38 insertions(+)

diff --git a/src/Riok.Mapperly/AnalyzerReleases.Shipped.md b/src/Riok.Mapperly/AnalyzerReleases.Shipped.md
index 9841c7b8ba..d567dda277 100644
--- a/src/Riok.Mapperly/AnalyzerReleases.Shipped.md
+++ b/src/Riok.Mapperly/AnalyzerReleases.Shipped.md
@@ -151,3 +151,4 @@ RMG063  | Mapper   | Error    | Cannot configure an enum mapping on a non-enum m
 RMG064  | Mapper   | Error    | Cannot configure an object mapping on a non-object mapping
 RMG065  | Mapper   | Warning  | Cannot configure an object mapping on a queryable projection mapping, apply the configurations to an object mapping method instead
 RMG066  | Mapper   | Warning | No members are mapped in an object mapping
+RMG067  | Mapper   | Error    | Invalid usage of the MapPropertyAttribute
diff --git a/src/Riok.Mapperly/Configuration/MapperConfigurationReader.cs b/src/Riok.Mapperly/Configuration/MapperConfigurationReader.cs
index 99bb9c9dbd..31596f4fbc 100644
--- a/src/Riok.Mapperly/Configuration/MapperConfigurationReader.cs
+++ b/src/Riok.Mapperly/Configuration/MapperConfigurationReader.cs
@@ -106,6 +106,11 @@ private MembersMappingConfiguration BuildMembersConfig(MappingConfigurationRefer
             return MapperConfiguration.Members;
         }
 
+        foreach (var invalidMemberConfigs in memberConfigurations.Where(x => !x.IsValid))
+        {
+            diagnostics.ReportDiagnostic(DiagnosticDescriptors.InvalidMapPropertyAttributeUsage, invalidMemberConfigs.Location);
+        }
+
         return new MembersMappingConfiguration(
             ignoredSourceMembers,
             ignoredTargetMembers,
diff --git a/src/Riok.Mapperly/Configuration/MemberMappingConfiguration.cs b/src/Riok.Mapperly/Configuration/MemberMappingConfiguration.cs
index 45f270ae85..33a7569ee5 100644
--- a/src/Riok.Mapperly/Configuration/MemberMappingConfiguration.cs
+++ b/src/Riok.Mapperly/Configuration/MemberMappingConfiguration.cs
@@ -10,5 +10,7 @@ public record MemberMappingConfiguration(StringMemberPath Source, StringMemberPa
 
     public string? Use { get; set; }
 
+    public bool IsValid => Use == null || FormatProvider == null && StringFormat == null;
+
     public TypeMappingConfiguration ToTypeMappingConfiguration() => new(StringFormat, FormatProvider, Use);
 }
diff --git a/src/Riok.Mapperly/Diagnostics/DiagnosticDescriptors.cs b/src/Riok.Mapperly/Diagnostics/DiagnosticDescriptors.cs
index a96af32fe4..1b1635d0f4 100644
--- a/src/Riok.Mapperly/Diagnostics/DiagnosticDescriptors.cs
+++ b/src/Riok.Mapperly/Diagnostics/DiagnosticDescriptors.cs
@@ -583,6 +583,15 @@ public static class DiagnosticDescriptors
         helpLinkUri: BuildHelpUri("RMG066")
     );
 
+    public static readonly DiagnosticDescriptor InvalidMapPropertyAttributeUsage = new DiagnosticDescriptor(
+        "RMG067",
+        "Invalid usage of the MapPropertyAttribute",
+        "Invalid usage of the MapPropertyAttribute",
+        DiagnosticCategories.Mapper,
+        DiagnosticSeverity.Error,
+        true
+    );
+
     private static string BuildHelpUri(string id)
     {
 #if ENV_NEXT
diff --git a/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyTest.cs b/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyTest.cs
index f39b16a37f..4b6f4c3f4f 100644
--- a/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyTest.cs
+++ b/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyTest.cs
@@ -496,4 +496,25 @@ public void ModifyingPathIfClassPrecedesShouldNotDiagnostic()
                 """
             );
     }
+
+    [Fact]
+    public void InvalidMapPropertyAttributeUsageShouldDiagnostic()
+    {
+        var source = TestSourceBuilder.MapperWithBodyAndTypes(
+            """
+            [MapProperty("IntValue", "StringValue", StringFormat = "D", Use = nameof(IntToString))]
+            partial B Map(A src);
+
+            string IntToString(int x) => x.ToString();
+            """,
+            "class A { public int IntValue { get; set; } }",
+            "class B { public string StringValue { get; set; } }"
+        );
+
+        TestHelper
+            .GenerateMapper(source, TestHelperOptions.AllowDiagnostics)
+            .Should()
+            .HaveDiagnostic(DiagnosticDescriptors.InvalidMapPropertyAttributeUsage, "Invalid usage of the MapPropertyAttribute")
+            .HaveAssertedAllDiagnostics();
+    }
 }