Second half of fix to dotnet#106

src/fsharp/CompileOps.fs

@@ -3846,11 +3846,20 @@ type TcImports(tcConfigP:TcConfigProvider, initialResolutions:TcAssemblyResoluti
                    referencedAssemblies   = [| for r in resolutions.GetAssemblyResolutions() -> r.resolvedPath |]
                    temporaryFolder        = Path.GetTempPath() }
 
+            // The type provider should not hold strong references to disposed
+            // TcImport objects.  So the callbacks provided in the type provider config
+            // dispatch via a thunk which gets set to a non-resource-capturing 
+            // failing function when the object is disposed. 
+            let systemRuntimeContainsType =  
+                let systemRuntimeContainsTypeRef = ref tcImports.SystemRuntimeContainsType  
+                tcImports.AttachDisposeAction(fun () -> systemRuntimeContainsTypeRef := (fun _ -> raise (System.ObjectDisposedException("The type provider has been disposed"))))  
+                fun arg -> systemRuntimeContainsTypeRef.Value arg  
+
             let providers = 
                 [ for assemblyName in providerAssemblies do
                       yield ExtensionTyping.GetTypeProvidersOfAssembly(displayPSTypeProviderSecurityDialogBlockingUI, tcConfig.validateTypeProviders, tpApprovals, 
                                                                        fileNameOfRuntimeAssembly, ilScopeRefOfRuntimeAssembly, assemblyName, typeProviderEnvironment, 
-                                                                       tcConfig.isInvalidationSupported, tcConfig.isInteractive, tcImports.SystemRuntimeContainsType, systemRuntimeAssemblyVersion, m) ]
+                                                                       tcConfig.isInvalidationSupported, tcConfig.isInteractive, systemRuntimeContainsType, systemRuntimeAssemblyVersion, m) ]
             let wasApproved = providers |> List.forall (fun (ok,_) -> ok)
             let providers = providers |> List.map snd |> List.concat