ReSharper.FSharp/src/FSharp/FSharp.Psi/src/Impl/Tree/FSharpCachedDeclarationBase.cs

using JetBrains.Diagnostics;
using JetBrains.ReSharper.Psi;
using JetBrains.ReSharper.Psi.ExtensionsAPI.Caches2;

namespace JetBrains.ReSharper.Plugins.FSharp.Psi.Impl.Tree
{
  internal abstract class FSharpCachedDeclarationBase : FSharpTypeMemberDeclarationBase, ICachedDeclaration2
  {
    protected override void PreInit()
    {
      base.PreInit();
      CacheDeclaredElement = null;
    }

    public override IDeclaredElement DeclaredElement
    {
      get
      {
        Assertion.Assert(IsValid(), "Getting declared element from invalid declaration");
        Assertion.Assert(CacheDeclaredElement == null || CacheDeclaredElement.IsValid(),
          "myCacheDeclaredElement == null || myCacheDeclaredElement.IsValid()");
        return CacheDeclaredElement;
      }
    }

    public IDeclaredElement CacheDeclaredElement { get; set; }
  }
}