From 9b74e8fb025809035a5dda0d6d91fb34f5f6d6ef Mon Sep 17 00:00:00 2001
From: Tim M <49349513+TimothyMakkison@users.noreply.github.com>
Date: Tue, 25 Jul 2023 17:23:23 +0100
Subject: [PATCH] fix: incorrect initialization for nullable nested memberpath
 unflattening (#591)

---
 src/Riok.Mapperly/Symbols/MemberPath.cs       |  2 +-
 .../Mapping/ObjectPropertyFlatteningTest.cs   | 26 +++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/Riok.Mapperly/Symbols/MemberPath.cs b/src/Riok.Mapperly/Symbols/MemberPath.cs
index 2bf154a9a1..4ed923cdbf 100644
--- a/src/Riok.Mapperly/Symbols/MemberPath.cs
+++ b/src/Riok.Mapperly/Symbols/MemberPath.cs
@@ -65,7 +65,7 @@ public IEnumerable<IReadOnlyList<IMappableMember>> ObjectPathNullableSubPaths()
             if (!pathPart.IsNullable)
                 continue;
 
-            yield return pathParts;
+            yield return pathParts.ToArray();
         }
     }
 
diff --git a/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyFlatteningTest.cs b/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyFlatteningTest.cs
index 20ef901a93..361ee1267b 100644
--- a/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyFlatteningTest.cs
+++ b/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyFlatteningTest.cs
@@ -302,6 +302,32 @@ public void ManualUnflattenedPropertyNullablePath()
             );
     }
 
+    [Fact]
+    public void ManualUnflattenedPropertyDeepNullablePath()
+    {
+        var source = TestSourceBuilder.MapperWithBodyAndTypes(
+            "[MapProperty($\"MyValueId\", \"Value.Nested.Id\"), MapProperty($\"MyValueId2\", \"Value.Nested.Id2\")] partial B Map(A source);",
+            "class A { public string MyValueId { get; set; } public string MyValueId2 { get; set; } }",
+            "class B { public C? Value { get; set; } }",
+            "class C { public D? Nested { get; set; } }",
+            "class D { public string Id { get; set; } public string Id2 { get; set; } }"
+        );
+
+        TestHelper
+            .GenerateMapper(source)
+            .Should()
+            .HaveSingleMethodBody(
+                """
+                var target = new global::B();
+                target.Value ??= new();
+                target.Value.Nested ??= new();
+                target.Value.Nested.Id = source.MyValueId;
+                target.Value.Nested.Id2 = source.MyValueId2;
+                return target;
+                """
+            );
+    }
+
     [Fact]
     public Task ManualUnflattenedPropertyNullablePathNoParameterlessCtorShouldDiagnostic()
     {