Thank you for this contribution, whats the reason for introducing the temporary field in the generated code?

If the member access is a property, you can not pass it as a reference. Since it's really a function call. So it need to take the reference and then assign it back.

var a = new ClassWithProperty();

// this
FunctionWithRefParam(ref a.Property);
// becomes this (kind of)
FunctionWithRefParam(ref a.get_Property());

I've also rebased on latest main.

That last failing test, I hope it's fixed now, but no idea why it broke for .NET 4.8.

The tests are failing due to the non-nullable not initialized array field in the integration tests: https://github.com/riok/mapperly/actions/runs/16592052238/job/46930700287?pr=1895#step:4:22

The integration test for the .net framework is failing since we generate slightly different code for the .net framework. Instead of #nullable enable we use #nullable enable annotations there. So your [VersionedSnapshot(Versions.NET6_0)] was correct, sorry about that. The test should pass if you add [VersionedSnapshot(Versions.NET6_0)], copy the snapshot UseUserMethodWithRefTest.SnapshotGeneratedSource.verified.cs as UseUserMethodWithRefTest.SnapshotGeneratedSource_NET6_0.verified.cs and replace #nullable enable with #nullable enable annotations in UseUserMethodWithRefTest.SnapshotGeneratedSource.verified.cs.

Alright that should then fix it, I mirrored the nullable annotation from UseExternalMapperTest.SnapshotGeneratedSource_NET6_0.verified.cs

I understand the issue now, it needs both snapshots.

Thank you for this great contribution! 🥳