Wrong Collection initializer

[Solaestas]

Input code

public class Test
{
	public static Test Create()
	{
		var ins = new Test();
		ins.Add(2);
		ins.Add(2);
		return ins;
	}
}

public static class TestExtension
{
	public static void Add(this Test obj, int value) { }
}

Erroneous output

public class Test
{
	public static Test Create()
	{
		return new Test { 2, 2 };
	}
}

public static class TestExtension
{
	public static void Add(this Test obj, int value)
	{
	}
}

Language version is C# 10.0 / VS2022
Collection initializer requires its type 'type' to implement System.Collections.IEnumerable.

Details

• Product in use: VS extension
• Version in use: 8.1.1.7464

[siegfriedpammer]

This is one is funny, because we already check for exactly that:

ILSpy/ICSharpCode.Decompiler/IL/Transforms/TransformCollectionAndObjectInitializers.cs

Lines 447 to 448 in d2d1c33

	if (!targetType.GetAllBaseTypes().Any(i => i.IsKnownType(KnownTypeCode.IEnumerable) || i.IsKnownType(KnownTypeCode.IEnumerableOfT)))
	return false;

[siegfriedpammer]

Cannot reproduce

[Solaestas]

I just found that it only happens on Release

[Solaestas]