anchor.diff:                  if not(inMidstOfReloading) && not(VsBuildManagerAccessorExtensionMethods.IsInProgress(accessor)) then
   #else
                   if not(inMidstOfReloading) && not(FSharpBuildStatus.IsInProgress) then
  -#endif
  -#if DEBUG
  -                    use t = Trace.Call("ProjectSystem", "FSharpProjectNode::ComputeSourcesAndFlags()", fun _ -> x.ProjectFile)
   #endif
                       // REVIEW CompilerFlags will be stale since last 'save' of MSBuild .fsproj file - can we do better?
                       try
  
positive.code:                             // which will finally populate sourcesAndFlags with good values.
                              // This means that ones the user fixes the problem, proper intellisense etc. should start immediately lighting up.
                              sourcesAndFlags <- Some([||],[||])
  #if DEBUG
                              Trace.PrintLine("ProjectSystem", fun _ -> "First call to ComputeSourcesAndFlags failed")
  #endif
                              projectSite.Open(x.CreateRunningProjectSite())
                          ()
                      | _ -> ()
  
negative.code:                         // If property is not set - msbuild will resolve only primary dependencies,
                          // and compiler will be very unhappy when during processing of referenced assembly it will discover that all fundamental types should be
                          // taken from System.Runtime that is not supplied
                          let _ = x.InvokeMsBuild("Compile", isBeingCalledByComputeSourcesAndFlags = true, extraProperties = [KeyValuePair("_ResolveReferenceDependencies", "true")])
                          sourcesAndFlagsNotifier.Notify()
                      finally
                          actuallyBuild <- true 
  