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:             // for example. If necessary, this can be changed - but please just try to avoid doing a gratuitous rename.
              let mutable sourcesAndFlags : option<(array<string> * array<string>)> = None
  #if DEBUG
              let mutable shouldLog = false // can poke this in the debugger to turn on logging
              let logger = new Microsoft.Build.BuildEngine.ConsoleLogger(Microsoft.Build.Framework.LoggerVerbosity.Diagnostic,
                                  (fun s -> 
                                      let self = this
                                      ignore self // ensure debugger has local in scope, so can poke self.shouldLog
                                      if shouldLog then 
                                          Trace.Print("MSBuild", fun _ -> "MSBuild: " + s)),
                                  (fun _ -> ()),
                                  (fun _ -> ())    )
  #endif
  
negative.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([||],[||])
                              projectSite.Open(x.CreateRunningProjectSite())
                          ()
                      | _ -> ()
  