anchor.diff:                            ilg.Emit(OpCodes.Castclass, targetTy)
                                 
                           popIfEmptyExpected expectedState
  -                    | Quotations.DerivedPatterns.SpecificCall <@ (-) @>(None, [t1; t2; t3], [a1; a2]) ->
  +                    | Quotations.DerivedPatterns.SpecificCall <@ (-) @>(None, [t1; t2; _], [a1; a2]) ->
                           assert(t1 = t2)
                           emit ExpectedStackState.Value a1
                           emit ExpectedStackState.Value a2
  
positive.code:     override this.GetCustomAttributes(_inherit)                                                    = [| |]
      override this.GetCustomAttributes(_attributeType, _inherit)                                    = [| |]
      override this.IsDefined(_attributeType, _inherit)                                              = false
  
  type ProvidedSymbolMethod(genericMethodDefinition: MethodInfo, parameters: Type list) =
      inherit System.Reflection.MethodInfo()
  
negative.code:                 emitExpr (ilg, copyOfLocals, [| Quotations.Var("this", lambda); v|]) expectedState body
                  ilg.Emit(OpCodes.Ret) 
  
                  lambda.CreateType() |> ignore
  
                  callSiteIlg.Emit(OpCodes.Newobj, ctor)
                  for (v, f) in fields do
  