Adding an interface to a partial class

The problem must be somewhere else, because you can implement interface in the other part of partial class than it's set on. I just tried following and it compiles just fine:

public interface IFoo
{
    int Bar { get; set; }
}

public partial class Foo
{
    public int Bar { get; set; }
}

public partial class Foo : IFoo
{

}

The properties probably use different types in interface and class.

Here's a quick checklist. Do the classes have identical:

• Names?
• Namespaces?
• Access modifiers?

Example:

• You decide to split an existing class into two files.
• The original file's namespace doesn't match its folder path.
• Consequently, the new class file you create has a mismatching namespace.
• Build fails.