TransparentCompiler.fs

namespace FSharp.Compiler.CodeAnalysis.TransparentCompiler

open System
open System.Collections.Generic
open System.Runtime.CompilerServices
open System.Diagnostics
open System.IO

open Internal.Utilities.Collections
open Internal.Utilities.Library

open FSharp.Compiler
open FSharp.Compiler.AbstractIL.IL
open FSharp.Compiler.AbstractIL.ILBinaryReader
open FSharp.Compiler.BuildGraph
open FSharp.Compiler.CodeAnalysis
open FSharp.Compiler.CompilerConfig
open FSharp.Compiler.CompilerImports
open FSharp.Compiler.CompilerOptions
open FSharp.Compiler.CheckBasics
open FSharp.Compiler.DependencyManager
open FSharp.Compiler.Diagnostics
open FSharp.Compiler.DiagnosticsLogger
open FSharp.Compiler.IO
open FSharp.Compiler.ScriptClosure
open FSharp.Compiler.Symbols
open FSharp.Compiler.TcGlobals
open FSharp.Compiler.Text
open FSharp.Compiler.Text.Range
open FSharp.Compiler.Xml
open System.Threading.Tasks
open FSharp.Compiler.ParseAndCheckInputs
open FSharp.Compiler.GraphChecking
open FSharp.Compiler.Syntax
open FSharp.Compiler.CompilerDiagnostics
open FSharp.Compiler.NameResolution
open Internal.Utilities.Library.Extras
open FSharp.Compiler.TypedTree
open FSharp.Compiler.CheckDeclarations
open FSharp.Compiler.EditorServices
open FSharp.Compiler.CodeAnalysis
open FSharp.Compiler.CreateILModule
open FSharp.Compiler.TypedTreeOps
open System.Threading
open Internal.Utilities.Hashing

open FSharp.Compiler.CodeAnalysis.ProjectSnapshot

/// Accumulated results of type checking. The minimum amount of state in order to continue type-checking following files.
[<NoEquality; NoComparison>]
type internal TcInfo =
    {
        tcState: TcState
        tcEnvAtEndOfFile: TcEnv

        /// Disambiguation table for module names
        moduleNamesDict: ModuleNamesDict

        topAttribs: TopAttribs option

        latestCcuSigForFile: ModuleOrNamespaceType option

        /// Accumulated diagnostics, last file first
        tcDiagnosticsRev: (PhasedDiagnostic * FSharpDiagnosticSeverity)[] list

        tcDependencyFiles: string list

        sigNameOpt: (string * QualifiedNameOfFile) option

        graphNode: NodeToTypeCheck option

        stateContainsNodes: Set<NodeToTypeCheck>

        sink: TcResultsSinkImpl list
    }

    member x.TcDiagnostics = Array.concat (List.rev x.tcDiagnosticsRev)

[<NoEquality; NoComparison>]
type internal TcIntermediate =
    {
        finisher: Finisher<NodeToTypeCheck, TcState, PartialResult>
        //tcEnvAtEndOfFile: TcEnv

        /// Disambiguation table for module names
        moduleNamesDict: ModuleNamesDict

        /// Accumulated diagnostics, last file first
        tcDiagnosticsRev: (PhasedDiagnostic * FSharpDiagnosticSeverity)[] list

        tcDependencyFiles: string list

        sink: TcResultsSinkImpl
    }

/// Things we need to start parsing and checking files for a given project snapshot
type internal BootstrapInfo =
    {
        // Each instance gets an Id on creation, unfortunately partial type check results using different instances are not compatible
        // So if this needs to be recreated for whatever reason then we need to re type check all files
        Id: int

        AssemblyName: string
        OutFile: string
        TcConfig: TcConfig
        TcImports: TcImports
        TcGlobals: TcGlobals
        InitialTcInfo: TcInfo

        // TODO: Figure out how these work and if they need to be added to the snapshot...
        LoadedSources: (range * FSharpFileSnapshot) list

        // TODO: Might be a bit more complicated if we want to support adding files to the project via OtherOptions
        // ExtraSourceFilesAfter: FSharpFileSnapshot list

        LoadClosure: LoadClosure option
        LastFileName: string
    }

type internal TcIntermediateResult = TcInfo * TcResultsSinkImpl * CheckedImplFile option * string

[<RequireQualifiedAccess>]
type internal DependencyGraphType =
    /// A dependency graph for a single file - it will be missing files which this file does not depend on
    | File
    /// A dependency graph for a project - it will contain all files in the project
    | Project

[<Extension>]
type internal Extensions =
    [<Extension>]
    static member Key<'T when 'T :> IFileSnapshot>(fileSnapshots: 'T list, ?extraKeyFlag) =

        { new ICacheKey<_, _> with
            member _.GetLabel() =
                let lastFile =
                    fileSnapshots
                    |> List.tryLast
                    |> Option.map (fun f -> f.FileName |> shortPath)
                    |> Option.defaultValue "[no file]"

                $"%d{fileSnapshots.Length} files ending with {lastFile}"

            member _.GetKey() =
                Md5Hasher.empty
                |> Md5Hasher.addStrings (fileSnapshots |> Seq.map (fun f -> f.FileName))
                |> pair extraKeyFlag

            member _.GetVersion() =
                Md5Hasher.empty
                |> Md5Hasher.addBytes' (fileSnapshots |> Seq.map (fun f -> f.Version))
                |> Md5Hasher.toString
        }

[<AutoOpen>]
module private TypeCheckingGraphProcessing =
    open FSharp.Compiler.GraphChecking.GraphProcessing

    // TODO Do we need to suppress some error logging if we
    // TODO apply the same partial results multiple times?
    // TODO Maybe we can enable logging only for the final fold
    /// <summary>
    /// Combine type-checking results of dependencies needed to type-check a 'higher' node in the graph
    /// </summary>
    /// <param name="emptyState">Initial state</param>
    /// <param name="deps">Direct dependencies of a node</param>
    /// <param name="transitiveDeps">Transitive dependencies of a node</param>
    /// <param name="folder">A way to fold a single result into existing state</param>
    let private combineResults
        (emptyState: TcInfo)
        (deps: ProcessedNode<NodeToTypeCheck, TcInfo * Finisher<NodeToTypeCheck, TcInfo, PartialResult>> array)
        (transitiveDeps: ProcessedNode<NodeToTypeCheck, TcInfo * Finisher<NodeToTypeCheck, TcInfo, PartialResult>> array)
        (folder: TcInfo -> Finisher<NodeToTypeCheck, TcInfo, PartialResult> -> TcInfo)
        : TcInfo =
        match deps with
        | [||] -> emptyState
        | _ ->
            // Instead of starting with empty state,
            // reuse state produced by the dependency with the biggest number of transitive dependencies.
            // This is to reduce the number of folds required to achieve the final state.
            let biggestDependency =
                let sizeMetric (node: ProcessedNode<_, _>) = node.Info.TransitiveDeps.Length
                deps |> Array.maxBy sizeMetric

            let firstState = biggestDependency.Result |> fst

            // Find items not already included in the state.
            let itemsPresent =
                set
                    [|
                        yield! biggestDependency.Info.TransitiveDeps
                        yield biggestDependency.Info.Item
                    |]

            let resultsToAdd =
                transitiveDeps
                |> Array.filter (fun dep -> itemsPresent.Contains dep.Info.Item = false)
                |> Array.distinctBy (fun dep -> dep.Info.Item)
                |> Array.sortWith (fun a b ->
                    // We preserve the order in which items are folded to the state.
                    match a.Info.Item, b.Info.Item with
                    | NodeToTypeCheck.PhysicalFile aIdx, NodeToTypeCheck.PhysicalFile bIdx
                    | NodeToTypeCheck.ArtificialImplFile aIdx, NodeToTypeCheck.ArtificialImplFile bIdx -> aIdx.CompareTo bIdx
                    | NodeToTypeCheck.PhysicalFile _, NodeToTypeCheck.ArtificialImplFile _ -> -1
                    | NodeToTypeCheck.ArtificialImplFile _, NodeToTypeCheck.PhysicalFile _ -> 1)
                |> Array.map (fun dep -> dep.Result |> snd)

            // Fold results not already included and produce the final state
            let state = Array.fold folder firstState resultsToAdd
            state

    /// <summary>
    /// Process a graph of items.
    /// A version of 'GraphProcessing.processGraph' with a signature specific to type-checking.
    /// </summary>
    let processTypeCheckingGraph
        (graph: Graph<NodeToTypeCheck>)
        (work: NodeToTypeCheck -> TcInfo -> Async<Finisher<NodeToTypeCheck, TcInfo, PartialResult>>)
        (emptyState: TcInfo)
        : Async<(int * PartialResult) list * TcInfo> =
        async {

            let workWrapper
                (getProcessedNode:
                    NodeToTypeCheck -> ProcessedNode<NodeToTypeCheck, TcInfo * Finisher<NodeToTypeCheck, TcInfo, PartialResult>>)
                (node: NodeInfo<NodeToTypeCheck>)
                : Async<TcInfo * Finisher<NodeToTypeCheck, TcInfo, PartialResult>> =
                async {
                    let folder (state: TcInfo) (Finisher(finisher = finisher)) : TcInfo = finisher state |> snd
                    let deps = node.Deps |> Array.except [| node.Item |] |> Array.map getProcessedNode

                    let transitiveDeps =
                        node.TransitiveDeps
                        |> Array.except [| node.Item |]
                        |> Array.map getProcessedNode

                    let inputState = combineResults emptyState deps transitiveDeps folder

                    let! singleRes = work node.Item inputState
                    let state = folder inputState singleRes
                    return state, singleRes
                }

            let! results = processGraphAsync graph workWrapper

            let finalFileResults, state =
                (([], emptyState),
                 results
                 |> Array.choose (fun (item, res) ->
                     match item with
                     | NodeToTypeCheck.ArtificialImplFile _ -> None
                     | NodeToTypeCheck.PhysicalFile file -> Some(file, res)))
                ||> Array.fold (fun (fileResults, state) (item, (_, Finisher(finisher = finisher))) ->
                    let fileResult, state = finisher state
                    (item, fileResult) :: fileResults, state)

            return finalFileResults, state
        }

type internal CompilerCaches(sizeFactor: int) =

    let sf = sizeFactor

    member _.SizeFactor = sf

    member val ParseFile = AsyncMemoize(keepStrongly = 50 * sf, keepWeakly = 20 * sf, name = "ParseFile")

    member val ParseAndCheckFileInProject = AsyncMemoize(sf, 2 * sf, name = "ParseAndCheckFileInProject")

    member val ParseAndCheckAllFilesInProject = AsyncMemoizeDisabled(sf, 2 * sf, name = "ParseAndCheckFullProject")

    member val ParseAndCheckProject = AsyncMemoize(sf, 2 * sf, name = "ParseAndCheckProject")

    member val FrameworkImports = AsyncMemoize(sf, 2 * sf, name = "FrameworkImports")

    member val BootstrapInfoStatic = AsyncMemoize(sf, 2 * sf, name = "BootstrapInfoStatic")

    member val BootstrapInfo = AsyncMemoize(sf, 2 * sf, name = "BootstrapInfo")

    member val TcLastFile = AsyncMemoizeDisabled(sf, 2 * sf, name = "TcLastFile")

    member val TcIntermediate = AsyncMemoize(20 * sf, 20 * sf, name = "TcIntermediate")

    member val DependencyGraph = AsyncMemoize(sf, 2 * sf, name = "DependencyGraph")

    member val ProjectExtras = AsyncMemoizeDisabled(sf, 2 * sf, name = "ProjectExtras")

    member val AssemblyData = AsyncMemoize(sf, 2 * sf, name = "AssemblyData")

    member val SemanticClassification = AsyncMemoize(sf, 2 * sf, name = "SemanticClassification")

    member val ItemKeyStore = AsyncMemoize(sf, 2 * sf, name = "ItemKeyStore")

    member this.Clear(projects: Set<ProjectIdentifier>) =
        let shouldClear project = projects |> Set.contains project

        this.ParseFile.Clear(fst >> shouldClear)
        this.ParseAndCheckFileInProject.Clear(snd >> shouldClear)
        this.ParseAndCheckProject.Clear(shouldClear)
        this.BootstrapInfoStatic.Clear(shouldClear)
        this.BootstrapInfo.Clear(shouldClear)
        this.TcIntermediate.Clear(snd >> shouldClear)
        this.AssemblyData.Clear(shouldClear)
        this.SemanticClassification.Clear(snd >> shouldClear)
        this.ItemKeyStore.Clear(snd >> shouldClear)

type internal TransparentCompiler
    (
        legacyReferenceResolver,
        projectCacheSize,
        keepAssemblyContents,
        keepAllBackgroundResolutions,
        tryGetMetadataSnapshot,
        suggestNamesForErrors,
        keepAllBackgroundSymbolUses,
        enableBackgroundItemKeyStoreAndSemanticClassification,
        enablePartialTypeChecking,
        parallelReferenceResolution,
        captureIdentifiersWhenParsing,
        getSource: (string -> Async<ISourceText option>) option,
        useChangeNotifications,
        useSyntaxTreeCache
    ) as self =

    // Is having just one of these ok?
    let lexResourceManager = Lexhelp.LexResourceManager()

    // Mutable so we can easily clear them by creating a new instance
    let mutable caches = CompilerCaches(100)

    // TODO: do we need this?
    //let maxTypeCheckingParallelism = max 1 (Environment.ProcessorCount / 2)
    //let maxParallelismSemaphore = new SemaphoreSlim(maxTypeCheckingParallelism)

    // We currently share one global dependency provider for all scripts for the FSharpChecker.
    // For projects, one is used per project.
    //
    // Sharing one for all scripts is necessary for good performance from GetProjectOptionsFromScript,
    // which requires a dependency provider to process through the project options prior to working out
    // if the cached incremental builder can be used for the project.
    let dependencyProviderForScripts = new DependencyProvider()

    // Legacy events, they're used in tests... eventually they should go away
    let beforeFileChecked = Event<string * FSharpProjectOptions>()
    let fileParsed = Event<string * FSharpProjectOptions>()
    let fileChecked = Event<string * FSharpProjectOptions>()
    let projectChecked = Event<FSharpProjectOptions>()

    // use this to process not-yet-implemented tasks
    let backgroundCompiler =
        BackgroundCompiler(
            legacyReferenceResolver,
            projectCacheSize,
            keepAssemblyContents,
            keepAllBackgroundResolutions,
            tryGetMetadataSnapshot,
            suggestNamesForErrors,
            keepAllBackgroundSymbolUses,
            enableBackgroundItemKeyStoreAndSemanticClassification,
            enablePartialTypeChecking,
            parallelReferenceResolution,
            captureIdentifiersWhenParsing,
            getSource,
            useChangeNotifications,
            useSyntaxTreeCache
        )
        :> IBackgroundCompiler

    let ComputeFrameworkImports (tcConfig: TcConfig) frameworkDLLs nonFrameworkResolutions =
        let frameworkDLLsKey =
            frameworkDLLs
            |> List.map (fun ar -> ar.resolvedPath) // The cache key. Just the minimal data.
            |> List.sort // Sort to promote cache hits.

        // The data elements in this key are very important. There should be nothing else in the TcConfig that logically affects
        // the import of a set of framework DLLs into F# CCUs. That is, the F# CCUs that result from a set of DLLs (including
        // FSharp.Core.dll and mscorlib.dll) must be logically invariant of all the other compiler configuration parameters.
        let key =
            FrameworkImportsCacheKey(
                frameworkDLLsKey,
                tcConfig.primaryAssembly.Name,
                tcConfig.GetTargetFrameworkDirectories(),
                tcConfig.fsharpBinariesDir,
                tcConfig.langVersion.SpecifiedVersion
            )

        caches.FrameworkImports.Get(
            key,
            node {
                use _ = Activity.start "ComputeFrameworkImports" []
                let tcConfigP = TcConfigProvider.Constant tcConfig

                return! TcImports.BuildFrameworkTcImports(tcConfigP, frameworkDLLs, nonFrameworkResolutions)
            }
        )

    // Link all the assemblies together and produce the input typecheck accumulator
    let CombineImportedAssembliesTask
        (
            assemblyName,
            tcConfig: TcConfig,
            tcConfigP,
            tcGlobals,
            frameworkTcImports,
            nonFrameworkResolutions,
            unresolvedReferences,
            dependencyProvider,
            loadClosureOpt: LoadClosure option,
            basicDependencies,
            importsInvalidatedByTypeProvider: Event<unit>
        ) =

        node {
            let diagnosticsLogger =
                CompilationDiagnosticLogger("CombineImportedAssembliesTask", tcConfig.diagnosticsOptions)

            use _ = new CompilationGlobalsScope(diagnosticsLogger, BuildPhase.Parameter)

            let! tcImports =
                node {
                    try
                        let! tcImports =
                            TcImports.BuildNonFrameworkTcImports(
                                tcConfigP,
                                frameworkTcImports,
                                nonFrameworkResolutions,
                                unresolvedReferences,
                                dependencyProvider
                            )
#if !NO_TYPEPROVIDERS
                        // TODO: review and handle the event
                        tcImports.GetCcusExcludingBase()
                        |> Seq.iter (fun ccu ->
                            // When a CCU reports an invalidation, merge them together and just report a
                            // general "imports invalidated". This triggers a rebuild.
                            //
                            // We are explicit about what the handler closure captures to help reason about the
                            // lifetime of captured objects, especially in case the type provider instance gets leaked
                            // or keeps itself alive mistakenly, e.g. via some global state in the type provider instance.
                            //
                            // The handler only captures
                            //    1. a weak reference to the importsInvalidated event.
                            //
                            // The IncrementalBuilder holds the strong reference the importsInvalidated event.
                            //
                            // In the invalidation handler we use a weak reference to allow the IncrementalBuilder to
                            // be collected if, for some reason, a TP instance is not disposed or not GC'd.
                            let capturedImportsInvalidated = WeakReference<_>(importsInvalidatedByTypeProvider)

                            ccu.Deref.InvalidateEvent.Add(fun _ ->
                                match capturedImportsInvalidated.TryGetTarget() with
                                | true, tg -> tg.Trigger()
                                | _ -> ()))
#endif
#if NO_TYPEPROVIDERS
                        ignore importsInvalidatedByTypeProvider
#endif
                        return tcImports
                    with
                    | :? OperationCanceledException ->
                        // if it's been canceled then it shouldn't be needed anymore
                        return frameworkTcImports
                    | exn ->
                        Debug.Assert(false, sprintf "Could not BuildAllReferencedDllTcImports %A" exn)
                        diagnosticsLogger.Warning exn
                        return frameworkTcImports
                }

            let tcInitial, openDecls0 =
                GetInitialTcEnv(assemblyName, rangeStartup, tcConfig, tcImports, tcGlobals)

            let tcState =
                GetInitialTcState(rangeStartup, assemblyName, tcConfig, tcGlobals, tcImports, tcInitial, openDecls0)

            let loadClosureErrors =
                [
                    match loadClosureOpt with
                    | None -> ()
                    | Some loadClosure ->
                        for inp in loadClosure.Inputs do
                            yield! inp.MetaCommandDiagnostics
                ]

            let initialErrors =
                Array.append (Array.ofList loadClosureErrors) (diagnosticsLogger.GetDiagnostics())

            let tcInfo =
                {
                    tcState = tcState
                    tcEnvAtEndOfFile = tcInitial
                    topAttribs = None
                    latestCcuSigForFile = None
                    tcDiagnosticsRev = [ initialErrors ]
                    moduleNamesDict = Map.empty
                    tcDependencyFiles = basicDependencies
                    sigNameOpt = None
                    graphNode = None
                    stateContainsNodes = Set.empty
                    sink = []
                }

            return tcImports, tcInfo
        }

    let getProjectReferences (project: ProjectSnapshotBase<_>) userOpName =
        [
            for r in project.ReferencedProjects do

                match r with
                | FSharpReferencedProjectSnapshot.FSharpReference(nm, projectSnapshot) ->
                    // Don't use cross-project references for FSharp.Core, since various bits of code
                    // require a concrete FSharp.Core to exist on-disk. The only solutions that have
                    // these cross-project references to FSharp.Core are VisualFSharp.sln and FSharp.sln. The ramification
                    // of this is that you need to build FSharp.Core to get intellisense in those projects.

                    if
                        (try
                            Path.GetFileNameWithoutExtension(nm)
                         with _ ->
                             "")
                        <> GetFSharpCoreLibraryName()
                    then
                        { new IProjectReference with
                            member x.EvaluateRawContents() =
                                node {
                                    Trace.TraceInformation("FCS: {0}.{1} ({2})", userOpName, "GetAssemblyData", nm)

                                    return!
                                        self.GetAssemblyData(
                                            projectSnapshot.ProjectSnapshot,
                                            nm,
                                            userOpName + ".CheckReferencedProject(" + nm + ")"
                                        )
                                }

                            member x.TryGetLogicalTimeStamp(cache) =
                                // TODO:
                                None

                            member x.FileName = nm
                        }
                | FSharpReferencedProjectSnapshot.PEReference(getStamp, delayedReader) ->
                    { new IProjectReference with
                        member x.EvaluateRawContents() =
                            node {
                                let! ilReaderOpt = delayedReader.TryGetILModuleReader() |> NodeCode.FromCancellable

                                match ilReaderOpt with
                                | Some ilReader ->
                                    let ilModuleDef, ilAsmRefs = ilReader.ILModuleDef, ilReader.ILAssemblyRefs
                                    let data = RawFSharpAssemblyData(ilModuleDef, ilAsmRefs) :> IRawFSharpAssemblyData
                                    return ProjectAssemblyDataResult.Available data
                                | _ ->
                                    // Note 'false' - if a PEReference doesn't find an ILModuleReader then we don't
                                    // continue to try to use an on-disk DLL
                                    return ProjectAssemblyDataResult.Unavailable false
                            }

                        member x.TryGetLogicalTimeStamp _ = getStamp () |> Some
                        member x.FileName = delayedReader.OutputFile
                    }

                | FSharpReferencedProjectSnapshot.ILModuleReference(nm, getStamp, getReader) ->
                    { new IProjectReference with
                        member x.EvaluateRawContents() =
                            cancellable {
                                let ilReader = getReader ()
                                let ilModuleDef, ilAsmRefs = ilReader.ILModuleDef, ilReader.ILAssemblyRefs
                                let data = RawFSharpAssemblyData(ilModuleDef, ilAsmRefs) :> IRawFSharpAssemblyData
                                return ProjectAssemblyDataResult.Available data
                            }
                            |> NodeCode.FromCancellable

                        member x.TryGetLogicalTimeStamp _ = getStamp () |> Some
                        member x.FileName = nm
                    }
        ]

    let ComputeTcConfigBuilder (projectSnapshot: ProjectSnapshotBase<_>) =

        let useSimpleResolutionSwitch = "--simpleresolution"
        let commandLineArgs = projectSnapshot.CommandLineOptions
        let defaultFSharpBinariesDir = FSharpCheckerResultsSettings.defaultFSharpBinariesDir
        let useScriptResolutionRules = projectSnapshot.UseScriptResolutionRules

        let projectReferences =
            getProjectReferences projectSnapshot "ComputeTcConfigBuilder"

        // TODO: script support
        let loadClosureOpt: LoadClosure option = None

        let getSwitchValue (switchString: string) =
            match commandLineArgs |> List.tryFindIndex (fun s -> s.StartsWithOrdinal switchString) with
            | Some idx -> Some(commandLineArgs[idx].Substring(switchString.Length))
            | _ -> None

        let sdkDirOverride =
            match loadClosureOpt with
            | None -> None
            | Some loadClosure -> loadClosure.SdkDirOverride

        // see also fsc.fs: runFromCommandLineToImportingAssemblies(), as there are many similarities to where the PS creates a tcConfigB
        let tcConfigB =
            TcConfigBuilder.CreateNew(
                legacyReferenceResolver,
                defaultFSharpBinariesDir,
                implicitIncludeDir = projectSnapshot.ProjectDirectory,
                reduceMemoryUsage = ReduceMemoryFlag.Yes,
                isInteractive = useScriptResolutionRules,
                isInvalidationSupported = true,
                defaultCopyFSharpCore = CopyFSharpCoreFlag.No,
                tryGetMetadataSnapshot = tryGetMetadataSnapshot,
                sdkDirOverride = sdkDirOverride,
                rangeForErrors = range0
            )

        tcConfigB.primaryAssembly <-
            match loadClosureOpt with
            | None -> PrimaryAssembly.Mscorlib
            | Some loadClosure ->
                if loadClosure.UseDesktopFramework then
                    PrimaryAssembly.Mscorlib
                else
                    PrimaryAssembly.System_Runtime

        tcConfigB.resolutionEnvironment <- (LegacyResolutionEnvironment.EditingOrCompilation true)

        tcConfigB.conditionalDefines <-
            let define =
                if useScriptResolutionRules then
                    "INTERACTIVE"
                else
                    "COMPILED"

            define :: tcConfigB.conditionalDefines

        tcConfigB.projectReferences <- projectReferences

        tcConfigB.useSimpleResolution <- (getSwitchValue useSimpleResolutionSwitch) |> Option.isSome

        // Apply command-line arguments and collect more source files if they are in the arguments
        let sourceFilesNew =
            ApplyCommandLineArgs(tcConfigB, projectSnapshot.SourceFileNames, commandLineArgs)

        // Never open PDB files for the language service, even if --standalone is specified
        tcConfigB.openDebugInformationForLaterStaticLinking <- false

        tcConfigB.xmlDocInfoLoader <-
            { new IXmlDocumentationInfoLoader with
                /// Try to load xml documentation associated with an assembly by the same file path with the extension ".xml".
                member _.TryLoad(assemblyFileName) =
                    let xmlFileName = Path.ChangeExtension(assemblyFileName, ".xml")

                    // REVIEW: File IO - Will eventually need to change this to use a file system interface of some sort.
                    XmlDocumentationInfo.TryCreateFromFile(xmlFileName)
            }
            |> Some

        tcConfigB.parallelReferenceResolution <- parallelReferenceResolution
        tcConfigB.captureIdentifiersWhenParsing <- captureIdentifiersWhenParsing

        tcConfigB, sourceFilesNew, loadClosureOpt

    let mutable BootstrapInfoIdCounter = 0

    /// Bootstrap info that does not depend source files
    let ComputeBootstrapInfoStatic (projectSnapshot: ProjectCore, tcConfig: TcConfig, assemblyName: string, loadClosureOpt) =

        caches.BootstrapInfoStatic.Get(
            projectSnapshot.CacheKeyWith("BootstrapInfoStatic", assemblyName),
            node {
                use _ =
                    Activity.start
                        "ComputeBootstrapInfoStatic"
                        [|
                            Activity.Tags.project, projectSnapshot.ProjectFileName |> Path.GetFileName
                            "references", projectSnapshot.ReferencedProjects.Length.ToString()
                        |]

                // Resolve assemblies and create the framework TcImports. This caches a level of "system" references. No type providers are
                // included in these references.

                let frameworkDLLs, nonFrameworkResolutions, unresolvedReferences =
                    TcAssemblyResolutions.SplitNonFoundationalResolutions(tcConfig)

                // Prepare the frameworkTcImportsCache
                let! tcGlobals, frameworkTcImports = ComputeFrameworkImports tcConfig frameworkDLLs nonFrameworkResolutions

                // Note we are not calling diagnosticsLogger.GetDiagnostics() anywhere for this task.
                // This is ok because not much can actually go wrong here.
                let diagnosticsLogger =
                    CompilationDiagnosticLogger("nonFrameworkAssemblyInputs", tcConfig.diagnosticsOptions)

                use _ = new CompilationGlobalsScope(diagnosticsLogger, BuildPhase.Parameter)

                let tcConfigP = TcConfigProvider.Constant tcConfig

                let importsInvalidatedByTypeProvider = Event<unit>()

                let basicDependencies =
                    [
                        for UnresolvedAssemblyReference(referenceText, _) in unresolvedReferences do
                            // Exclude things that are definitely not a file name
                            if not (FileSystem.IsInvalidPathShim referenceText) then
                                let file =
                                    if FileSystem.IsPathRootedShim referenceText then
                                        referenceText
                                    else
                                        Path.Combine(projectSnapshot.ProjectDirectory, referenceText)

                                yield file

                        for r in nonFrameworkResolutions do
                            yield r.resolvedPath
                    ]

                // For scripts, the dependency provider is already available.
                // For projects create a fresh one for the project.
                let dependencyProvider =
                    if projectSnapshot.UseScriptResolutionRules then
                        dependencyProviderForScripts
                    else
                        new DependencyProvider()

                let! tcImports, initialTcInfo =
                    CombineImportedAssembliesTask(
                        assemblyName,
                        tcConfig,
                        tcConfigP,
                        tcGlobals,
                        frameworkTcImports,
                        nonFrameworkResolutions,
                        unresolvedReferences,
                        dependencyProvider,
                        loadClosureOpt,
                        basicDependencies,
                        importsInvalidatedByTypeProvider
                    )

                let bootstrapId = Interlocked.Increment &BootstrapInfoIdCounter

                return bootstrapId, tcImports, tcGlobals, initialTcInfo, importsInvalidatedByTypeProvider
            }
        )

    let computeBootstrapInfoInner (projectSnapshot: ProjectSnapshot) =
        node {

            let tcConfigB, sourceFiles, loadClosureOpt = ComputeTcConfigBuilder projectSnapshot

            // If this is a builder for a script, re-apply the settings inferred from the
            // script and its load closure to the configuration.
            //
            // NOTE: it would probably be cleaner and more accurate to re-run the load closure at this point.
            let setupConfigFromLoadClosure () =
                match loadClosureOpt with
                | Some loadClosure ->
                    let dllReferences =
                        [
                            for reference in tcConfigB.referencedDLLs do
                                // If there's (one or more) resolutions of closure references then yield them all
                                match
                                    loadClosure.References
                                    |> List.tryFind (fun (resolved, _) -> resolved = reference.Text)
                                with
                                | Some(resolved, closureReferences) ->
                                    for closureReference in closureReferences do
                                        yield AssemblyReference(closureReference.originalReference.Range, resolved, None)
                                | None -> yield reference
                        ]

                    tcConfigB.referencedDLLs <- []

                    tcConfigB.primaryAssembly <-
                        (if loadClosure.UseDesktopFramework then
                             PrimaryAssembly.Mscorlib
                         else
                             PrimaryAssembly.System_Runtime)
                    // Add one by one to remove duplicates
                    dllReferences
                    |> List.iter (fun dllReference -> tcConfigB.AddReferencedAssemblyByPath(dllReference.Range, dllReference.Text))

                    tcConfigB.knownUnresolvedReferences <- loadClosure.UnresolvedReferences
                | None -> ()

            setupConfigFromLoadClosure ()

            let tcConfig = TcConfig.Create(tcConfigB, validate = true)
            let outFile, _, assemblyName = tcConfigB.DecideNames sourceFiles

            let! bootstrapId, tcImports, tcGlobals, initialTcInfo, _importsInvalidatedByTypeProvider =
                ComputeBootstrapInfoStatic(projectSnapshot.ProjectCore, tcConfig, assemblyName, loadClosureOpt)

            // Check for the existence of loaded sources and prepend them to the sources list if present.
            let loadedSources =
                tcConfig.GetAvailableLoadedSources()
                |> List.map (fun (m, fileName) -> m, FSharpFileSnapshot.CreateFromFileSystem(fileName))

            return
                match sourceFiles with
                | [] -> None
                | _ ->
                    Some
                        {
                            Id = bootstrapId
                            AssemblyName = assemblyName
                            OutFile = outFile
                            TcConfig = tcConfig
                            TcImports = tcImports
                            TcGlobals = tcGlobals
                            InitialTcInfo = initialTcInfo
                            LoadedSources = loadedSources
                            LoadClosure = loadClosureOpt
                            LastFileName = sourceFiles |> List.tryLast |> Option.defaultValue ""
                        //ImportsInvalidatedByTypeProvider = importsInvalidatedByTypeProvider
                        }
        }

    let ComputeBootstrapInfo (projectSnapshot: ProjectSnapshot) =

        caches.BootstrapInfo.Get(
            projectSnapshot.NoFileVersionsKey,
            node {
                use _ =
                    Activity.start "ComputeBootstrapInfo" [| Activity.Tags.project, projectSnapshot.ProjectFileName |> Path.GetFileName |]

                // Trap and report diagnostics from creation.
                let delayedLogger = CapturingDiagnosticsLogger("IncrementalBuilderCreation")
                use _ = new CompilationGlobalsScope(delayedLogger, BuildPhase.Parameter)

                let! bootstrapInfoOpt =
                    node {
                        try
                            return! computeBootstrapInfoInner projectSnapshot
                        with exn ->
                            errorRecoveryNoRange exn
                            return None
                    }

                let diagnostics =
                    match bootstrapInfoOpt with
                    | Some bootstrapInfo ->
                        let diagnosticsOptions = bootstrapInfo.TcConfig.diagnosticsOptions

                        let diagnosticsLogger =
                            CompilationDiagnosticLogger("IncrementalBuilderCreation", diagnosticsOptions)

                        delayedLogger.CommitDelayedDiagnostics diagnosticsLogger
                        diagnosticsLogger.GetDiagnostics()
                    | _ -> Array.ofList delayedLogger.Diagnostics
                    |> Array.map (fun (diagnostic, severity) ->
                        let flatErrors =
                            bootstrapInfoOpt
                            |> Option.map (fun bootstrapInfo -> bootstrapInfo.TcConfig.flatErrors)
                            |> Option.defaultValue false // TODO: do we need to figure this out?

                        FSharpDiagnostic.CreateFromException(diagnostic, severity, range.Zero, suggestNamesForErrors, flatErrors, None))

                return bootstrapInfoOpt, diagnostics
            }
        )

    // TODO: Not sure if we should cache this. For VS probably not. Maybe it can be configurable by FCS user.
    let LoadSource (file: FSharpFileSnapshot) isExe isLastCompiland =
        node {
            let! source = file.GetSource() |> NodeCode.AwaitTask

            return
                FSharpFileSnapshotWithSource(
                    FileName = file.FileName,
                    Source = source,
                    SourceHash = source.GetChecksum(),
                    IsLastCompiland = isLastCompiland,
                    IsExe = isExe
                )
        }

    let LoadSources (bootstrapInfo: BootstrapInfo) (projectSnapshot: ProjectSnapshot) =
        node {
            let isExe = bootstrapInfo.TcConfig.target.IsExe

            let! sources =
                projectSnapshot.SourceFiles
                |> Seq.map (fun f -> LoadSource f isExe (f.FileName = bootstrapInfo.LastFileName))
                |> NodeCode.Parallel

            return ProjectSnapshotWithSources(projectSnapshot.ProjectCore, sources |> Array.toList)

        }

    let ComputeParseFile (projectSnapshot: ProjectSnapshotBase<_>) (tcConfig: TcConfig) (file: FSharpFileSnapshotWithSource) =

        let key =
            { new ICacheKey<_, _> with
                member _.GetLabel() = file.FileName |> shortPath

                member _.GetKey() =
                    projectSnapshot.ProjectCore.Identifier, file.FileName

                member _.GetVersion() =
                    projectSnapshot.ParsingVersion,
                    file.StringVersion,
                    // TODO: is there a situation where this is not enough and we need to have them separate?
                    file.IsLastCompiland && file.IsExe
            }

        caches.ParseFile.Get(
            key,
            node {
                use _ =
                    Activity.start
                        "ComputeParseFile"
                        [|
                            Activity.Tags.fileName, file.FileName |> shortPath
                            Activity.Tags.version, file.StringVersion
                        |]

                let diagnosticsLogger =
                    CompilationDiagnosticLogger("Parse", tcConfig.diagnosticsOptions)
                // Return the disposable object that cleans up
                use _holder = new CompilationGlobalsScope(diagnosticsLogger, BuildPhase.Parse)

                let flags = file.IsLastCompiland, file.IsExe
                let fileName = file.FileName
                let sourceText = file.Source

                let input =
                    ParseOneInputSourceText(tcConfig, lexResourceManager, fileName, flags, diagnosticsLogger, sourceText)

                // TODO: Hashing of syntax tree
                let inputHash = file.Version

                fileParsed.Trigger(fileName, Unchecked.defaultof<_>)

                return FSharpParsedFile(fileName, inputHash, sourceText, input, diagnosticsLogger.GetDiagnostics())
            }
        )

    // In case we don't want to use any parallel processing
    let mkLinearGraph count : Graph<FileIndex> =
        seq {
            0, [||]

            yield!
                [ 0 .. count - 1 ]
                |> Seq.rev
                |> Seq.pairwise
                |> Seq.map (fun (a, b) -> a, [| b |])
        }
        |> Graph.make

    let computeDependencyGraph (tcConfig: TcConfig) parsedInputs (processGraph: Graph<FileIndex> -> Graph<FileIndex>) =
        node {
            let sourceFiles: FileInProject array =
                parsedInputs
                |> Seq.toArray
                |> Array.mapi (fun idx (input: ParsedInput) ->
                    {
                        Idx = idx
                        FileName = input.FileName
                        ParsedInput = input
                    })

            use _ =
                Activity.start "ComputeDependencyGraph" [| Activity.Tags.fileName, (sourceFiles |> Array.last).FileName |]

            let filePairs = FilePairMap(sourceFiles)

            // TODO: we will probably want to cache and re-use larger graphs if available

            let graph =
                if tcConfig.compilingFSharpCore then
                    mkLinearGraph sourceFiles.Length
                else
                    DependencyResolution.mkGraph filePairs sourceFiles |> fst |> processGraph

            let nodeGraph = TransformDependencyGraph(graph, filePairs)

            let fileNames =
                parsedInputs
                |> Seq.mapi (fun idx input -> idx, Path.GetFileName input.FileName)
                |> Map.ofSeq

            let debugGraph =
                nodeGraph
                |> Graph.map (function
                    | NodeToTypeCheck.PhysicalFile i -> i, $"[{i}] {fileNames[i]}"
                    | NodeToTypeCheck.ArtificialImplFile i -> -(i + 1), $"AIF [{i}] : {fileNames[i]}")
                |> Graph.serialiseToMermaid

            //Trace.TraceInformation("\n" + debugGraph)

            if Activity.Current <> null then
                Activity.Current.AddTag("graph", debugGraph) |> ignore

            return nodeGraph, graph
        }

    let removeImplFilesThatHaveSignatures (projectSnapshot: ProjectSnapshot) (graph: Graph<FileIndex>) =

        let removeIndexes =
            projectSnapshot.SourceFileNames
            |> Seq.mapi pair
            |> Seq.groupBy (
                snd
                >> (fun fileName ->
                    if fileName.EndsWith(".fsi") then
                        fileName.Substring(0, fileName.Length - 1)
                    else
                        fileName)
            )
            |> Seq.map (snd >> (Seq.toList))
            |> Seq.choose (function
                | [ idx1, _; idx2, _ ] -> max idx1 idx2 |> Some
                | _ -> None)
            |> Set

        graph
        |> Seq.filter (fun x -> not (removeIndexes.Contains x.Key))
        |> Seq.map (fun x -> x.Key, x.Value |> Array.filter (fun node -> not (removeIndexes.Contains node)))
        |> Graph.make

    let removeImplFilesThatHaveSignaturesExceptLastOne (projectSnapshot: ProjectSnapshotBase<_>) (graph: Graph<FileIndex>) =

        let removeIndexes =
            projectSnapshot.SourceFileNames
            |> Seq.mapi pair
            |> Seq.groupBy (
                snd
                >> (fun fileName ->
                    if fileName.EndsWith(".fsi") then
                        fileName.Substring(0, fileName.Length - 1)
                    else
                        fileName)
            )
            |> Seq.map (snd >> (Seq.toList))
            |> Seq.choose (function
                | [ idx1, _; idx2, _ ] -> max idx1 idx2 |> Some
                | _ -> None)
            |> Set
            // Don't remove the last file
            |> Set.remove (projectSnapshot.SourceFiles.Length - 1)

        graph
        |> Seq.filter (fun x -> not (removeIndexes.Contains x.Key))
        |> Seq.map (fun x -> x.Key, x.Value |> Array.filter (fun node -> not (removeIndexes.Contains node)))
        |> Graph.make

    let ComputeDependencyGraphForFile (tcConfig: TcConfig) (priorSnapshot: ProjectSnapshotBase<FSharpParsedFile>) =
        let key = priorSnapshot.SourceFiles.Key(DependencyGraphType.File)
        //let lastFileIndex = (parsedInputs |> Array.length) - 1
        //caches.DependencyGraph.Get(key, computeDependencyGraph parsedInputs (Graph.subGraphFor lastFileIndex))
        caches.DependencyGraph.Get(
            key,
            computeDependencyGraph
                tcConfig
                (priorSnapshot.SourceFiles |> Seq.map (fun f -> f.ParsedInput))
                (removeImplFilesThatHaveSignaturesExceptLastOne priorSnapshot)
        )

    let ComputeDependencyGraphForProject (tcConfig: TcConfig) (projectSnapshot: ProjectSnapshotBase<FSharpParsedFile>) =

        let key = projectSnapshot.SourceFiles.Key(DependencyGraphType.Project)
        //caches.DependencyGraph.Get(key, computeDependencyGraph parsedInputs (removeImplFilesThatHaveSignatures projectSnapshot))
        caches.DependencyGraph.Get(
            key,
            computeDependencyGraph tcConfig (projectSnapshot.SourceFiles |> Seq.map (fun f -> f.ParsedInput)) id
        )

    let ComputeTcIntermediate
        (projectSnapshot: ProjectSnapshotBase<FSharpParsedFile>)
        (dependencyGraph: Graph<FileIndex>)
        (index: FileIndex)
        (nodeToCheck: NodeToTypeCheck)
        bootstrapInfo
        (prevTcInfo: TcInfo)
        =

        ignore dependencyGraph

        let key = projectSnapshot.FileKey(index).WithExtraVersion(bootstrapInfo.Id)

        let _label, _k, _version = key.GetLabel(), key.GetKey(), key.GetVersion()

        caches.TcIntermediate.Get(
            key,
            node {

                let file = projectSnapshot.SourceFiles[index]

                let input = file.ParsedInput
                let fileName = file.FileName

                use _ =
                    Activity.start
                        "ComputeTcIntermediate"
                        [|
                            Activity.Tags.fileName, fileName |> Path.GetFileName
                            "key", key.GetLabel()
                            "version", "-" // key.GetVersion()
                        |]

                beforeFileChecked.Trigger(fileName, Unchecked.defaultof<_>)

                let tcConfig = bootstrapInfo.TcConfig
                let tcGlobals = bootstrapInfo.TcGlobals
                let tcImports = bootstrapInfo.TcImports

                let mainInputFileName = file.FileName
                let sourceText = file.SourceText
                let parsedMainInput = file.ParsedInput

                // Initialize the error handler
                let errHandler =
                    ParseAndCheckFile.DiagnosticsHandler(
                        true,
                        mainInputFileName,
                        tcConfig.diagnosticsOptions,
                        sourceText,
                        suggestNamesForErrors,
                        tcConfig.flatErrors
                    )

                use _ =
                    new CompilationGlobalsScope(errHandler.DiagnosticsLogger, BuildPhase.TypeCheck)

                // Apply nowarns to tcConfig (may generate errors, so ensure diagnosticsLogger is installed)
                let tcConfig =
                    ApplyNoWarnsToTcConfig(tcConfig, parsedMainInput, Path.GetDirectoryName mainInputFileName)

                // update the error handler with the modified tcConfig
                errHandler.DiagnosticOptions <- tcConfig.diagnosticsOptions

                let diagnosticsLogger = errHandler.DiagnosticsLogger

                //let capturingDiagnosticsLogger = CapturingDiagnosticsLogger("TypeCheck")

                //let diagnosticsLogger =
                //    GetDiagnosticsLoggerFilteringByScopedPragmas(
                //        false,
                //        input.ScopedPragmas,
                //        tcConfig.diagnosticsOptions,
                //        capturingDiagnosticsLogger
                //    )

                //use _ = new CompilationGlobalsScope(diagnosticsLogger, BuildPhase.TypeCheck)

                //beforeFileChecked.Trigger fileName

                ApplyMetaCommandsFromInputToTcConfig(tcConfig, input, Path.GetDirectoryName fileName, tcImports.DependencyProvider)
                |> ignore

                let sink = TcResultsSinkImpl(tcGlobals, file.SourceText)

                let hadParseErrors = not (Array.isEmpty file.ParseErrors)

                let input, moduleNamesDict =
                    DeduplicateParsedInputModuleName prevTcInfo.moduleNamesDict input

                //let! ct = NodeCode.CancellationToken

                try
                    //do! maxParallelismSemaphore.WaitAsync(ct) |> NodeCode.AwaitTask

                    let! finisher =
                        CheckOneInputWithCallback
                            nodeToCheck
                            ((fun () -> hadParseErrors || diagnosticsLogger.ErrorCount > 0),
                             tcConfig,
                             tcImports,
                             tcGlobals,
                             None,
                             TcResultsSink.WithSink sink,
                             prevTcInfo.tcState,
                             input,
                             true)
                        |> Cancellable.toAsync
                        |> NodeCode.AwaitAsync

                    //fileChecked.Trigger fileName

                    fileChecked.Trigger(fileName, Unchecked.defaultof<_>)

                    return
                        {
                            finisher = finisher
                            moduleNamesDict = moduleNamesDict
                            tcDiagnosticsRev = [ errHandler.CollectedPhasedDiagnostics ]
                            tcDependencyFiles = [ fileName ]
                            sink = sink
                        }
                finally
                    ()
            //maxParallelismSemaphore.Release() |> ignore
            }
        )

    let processGraphNode projectSnapshot bootstrapInfo dependencyFiles collectSinks (fileNode: NodeToTypeCheck) tcInfo =
        // TODO: should this be node?
        async {
            match fileNode with
            | NodeToTypeCheck.PhysicalFile index ->

                let! tcIntermediate =
                    ComputeTcIntermediate projectSnapshot dependencyFiles index fileNode bootstrapInfo tcInfo
                    |> Async.AwaitNodeCode

                let (Finisher(node = node; finisher = finisher)) = tcIntermediate.finisher

                return
                    Finisher(
                        node,
                        (fun tcInfo ->

                            if tcInfo.stateContainsNodes |> Set.contains fileNode then
                                failwith $"Oops!"

                            //if
                            //    tcInfo.stateContainsNodes
                            // Signature files don't have to be right above the impl file... if we need this check then
                            // we need to do it differently
                            //    |> Set.contains (NodeToTypeCheck.ArtificialImplFile(index - 1))
                            //then
                            //  failwith $"Oops???"

                            let partialResult, tcState = finisher tcInfo.tcState

                            let tcEnv, topAttribs, _checkImplFileOpt, ccuSigForFile = partialResult

                            let tcEnvAtEndOfFile =
                                if keepAllBackgroundResolutions then
                                    tcEnv
                                else
                                    tcState.TcEnvFromImpls

                            partialResult,
                            { tcInfo with
                                tcState = tcState
                                tcEnvAtEndOfFile = tcEnvAtEndOfFile
                                moduleNamesDict = tcIntermediate.moduleNamesDict
                                topAttribs = Some topAttribs
                                tcDiagnosticsRev = tcIntermediate.tcDiagnosticsRev @ tcInfo.tcDiagnosticsRev
                                tcDependencyFiles = tcIntermediate.tcDependencyFiles @ tcInfo.tcDependencyFiles
                                latestCcuSigForFile = Some ccuSigForFile
                                graphNode = Some node
                                stateContainsNodes = tcInfo.stateContainsNodes |> Set.add node
                                sink =
                                    if collectSinks then
                                        tcIntermediate.sink :: tcInfo.sink
                                    else
                                        [ tcIntermediate.sink ]
                            })
                    )

            | NodeToTypeCheck.ArtificialImplFile index ->
                return
                    Finisher(
                        fileNode,
                        (fun tcInfo ->

                            if tcInfo.stateContainsNodes |> Set.contains fileNode then
                                failwith $"Oops!"

                            if
                                tcInfo.stateContainsNodes
                                |> Set.contains (NodeToTypeCheck.PhysicalFile(index + 1))
                            then
                                failwith $"Oops!!!"

                            let parsedInput = projectSnapshot.SourceFiles[index].ParsedInput
                            let prefixPathOpt = None
                            // Retrieve the type-checked signature information and add it to the TcEnvFromImpls.
                            let partialResult, tcState =
                                AddSignatureResultToTcImplEnv
                                    (bootstrapInfo.TcImports,
                                     bootstrapInfo.TcGlobals,
                                     prefixPathOpt,
                                     TcResultsSink.NoSink,
                                     tcInfo.tcState,
                                     parsedInput)
                                    tcInfo.tcState

                            let tcEnv, topAttribs, _checkImplFileOpt, ccuSigForFile = partialResult

                            let tcEnvAtEndOfFile =
                                if keepAllBackgroundResolutions then
                                    tcEnv
                                else
                                    tcState.TcEnvFromImpls

                            partialResult,
                            { tcInfo with
                                tcState = tcState
                                tcEnvAtEndOfFile = tcEnvAtEndOfFile
                                topAttribs = Some topAttribs
                                latestCcuSigForFile = Some ccuSigForFile
                                graphNode = Some fileNode
                                stateContainsNodes = tcInfo.stateContainsNodes |> Set.add fileNode
                            })
                    )

        }

    let parseSourceFiles (projectSnapshot: ProjectSnapshotWithSources) tcConfig =
        node {
            let! parsedInputs =
                projectSnapshot.SourceFiles
                |> Seq.map (ComputeParseFile projectSnapshot tcConfig)
                |> NodeCode.Parallel

            return ProjectSnapshotBase<_>(projectSnapshot.ProjectCore, parsedInputs |> Array.toList)
        }

    // Type check file and all its dependencies
    let ComputeTcLastFile (bootstrapInfo: BootstrapInfo) (projectSnapshot: ProjectSnapshotWithSources) =
        let fileName = projectSnapshot.SourceFiles |> List.last |> (fun f -> f.FileName)

        caches.TcLastFile.Get(
            projectSnapshot.FileKey fileName,
            node {
                let file = projectSnapshot.SourceFiles |> List.last

                use _ =
                    Activity.start "ComputeTcLastFile" [| Activity.Tags.fileName, file.FileName |> Path.GetFileName |]

                let! projectSnapshot = parseSourceFiles projectSnapshot bootstrapInfo.TcConfig

                let! graph, dependencyFiles = ComputeDependencyGraphForFile bootstrapInfo.TcConfig projectSnapshot

                let! results, tcInfo =
                    processTypeCheckingGraph
                        graph
                        (processGraphNode projectSnapshot bootstrapInfo dependencyFiles false)
                        bootstrapInfo.InitialTcInfo
                    |> NodeCode.AwaitAsync

                let lastResult = results |> List.head |> snd

                return lastResult, tcInfo
            }
        )

    let getParseResult (projectSnapshot: ProjectSnapshot) creationDiags file (tcConfig: TcConfig) =
        node {
            let! parsedFile = ComputeParseFile projectSnapshot tcConfig file

            let parseDiagnostics =
                DiagnosticHelpers.CreateDiagnostics(
                    tcConfig.diagnosticsOptions,
                    false,
                    file.FileName,
                    parsedFile.ParseErrors,
                    suggestNamesForErrors,
                    tcConfig.flatErrors,
                    None
                )

            let diagnostics = [| yield! creationDiags; yield! parseDiagnostics |]

            return
                FSharpParseFileResults(
                    diagnostics = diagnostics,
                    input = parsedFile.ParsedInput,
                    parseHadErrors = (parseDiagnostics.Length > 0),
                    // TODO: check if we really need this in parse results
                    dependencyFiles = [||]
                )
        }

    let emptyParseResult fileName diagnostics =
        let parseTree = EmptyParsedInput(fileName, (false, false))
        FSharpParseFileResults(diagnostics, parseTree, true, [||])

    let ComputeParseAndCheckFileInProject (fileName: string) (projectSnapshot: ProjectSnapshot) =
        caches.ParseAndCheckFileInProject.Get(
            projectSnapshot.FileKey fileName,
            node {

                use _ =
                    Activity.start "ComputeParseAndCheckFileInProject" [| Activity.Tags.fileName, fileName |> Path.GetFileName |]

                match! ComputeBootstrapInfo projectSnapshot with
                | None, creationDiags -> return emptyParseResult fileName creationDiags, FSharpCheckFileAnswer.Aborted

                | Some bootstrapInfo, creationDiags ->

                    let priorSnapshot = projectSnapshot.UpTo fileName
                    let! snapshotWithSources = LoadSources bootstrapInfo priorSnapshot
                    let file = snapshotWithSources.SourceFiles |> List.last

                    let! parseResults = getParseResult projectSnapshot Seq.empty file bootstrapInfo.TcConfig

                    let! result, tcInfo = ComputeTcLastFile bootstrapInfo snapshotWithSources

                    let (tcEnv, _topAttribs, checkedImplFileOpt, ccuSigForFile) = result

                    let tcState = tcInfo.tcState

                    let sink = tcInfo.sink.Head // TODO: don't use head

                    let tcResolutions = sink.GetResolutions()
                    let tcSymbolUses = sink.GetSymbolUses()
                    let tcOpenDeclarations = sink.GetOpenDeclarations()

                    let tcDependencyFiles = [] // TODO add as a set to TcIntermediate

                    // TODO: Apparently creating diagnostics can produce further diagnostics. So let's capture those too. Hopefully there is a more elegant solution...
                    // Probably diagnostics need to be evaluated during typecheck anyway for proper formatting, which might take care of this too.
                    let extraLogger = CapturingDiagnosticsLogger("DiagnosticsWhileCreatingDiagnostics")
                    use _ = new CompilationGlobalsScope(extraLogger, BuildPhase.TypeCheck)

                    // Apply nowarns to tcConfig (may generate errors, so ensure diagnosticsLogger is installed)
                    let tcConfig =
                        ApplyNoWarnsToTcConfig(bootstrapInfo.TcConfig, parseResults.ParseTree, Path.GetDirectoryName fileName)

                    let diagnosticsOptions = tcConfig.diagnosticsOptions

                    let symbolEnv =
                        SymbolEnv(bootstrapInfo.TcGlobals, tcState.Ccu, Some tcState.CcuSig, bootstrapInfo.TcImports)

                    let tcDiagnostics =
                        DiagnosticHelpers.CreateDiagnostics(
                            diagnosticsOptions,
                            false,
                            fileName,
                            tcInfo.TcDiagnostics,
                            suggestNamesForErrors,
                            bootstrapInfo.TcConfig.flatErrors,
                            Some symbolEnv
                        )

                    let extraDiagnostics =
                        DiagnosticHelpers.CreateDiagnostics(
                            diagnosticsOptions,
                            false,
                            fileName,
                            extraLogger.Diagnostics,
                            suggestNamesForErrors,
                            bootstrapInfo.TcConfig.flatErrors,
                            Some symbolEnv
                        )

                    let tcDiagnostics = [| yield! extraDiagnostics; yield! tcDiagnostics |]

                    let loadClosure = None // TODO: script support

                    let typedResults =
                        FSharpCheckFileResults.Make(
                            fileName,
                            projectSnapshot.ProjectFileName,
                            bootstrapInfo.TcConfig,
                            bootstrapInfo.TcGlobals,
                            projectSnapshot.IsIncompleteTypeCheckEnvironment,
                            None,
                            projectSnapshot.ToOptions(),
                            Array.ofList tcDependencyFiles,
                            creationDiags,
                            parseResults.Diagnostics,
                            tcDiagnostics,
                            keepAssemblyContents,
                            ccuSigForFile,
                            tcState.Ccu,
                            bootstrapInfo.TcImports,
                            tcEnv.AccessRights,
                            tcResolutions,
                            tcSymbolUses,
                            tcEnv.NameEnv,
                            loadClosure,
                            checkedImplFileOpt,
                            tcOpenDeclarations
                        )

                    return (parseResults, FSharpCheckFileAnswer.Succeeded typedResults)
            }
        )

    let ComputeParseAndCheckAllFilesInProject (bootstrapInfo: BootstrapInfo) (projectSnapshot: ProjectSnapshotWithSources) =
        caches.ParseAndCheckAllFilesInProject.Get(
            projectSnapshot.FullKey,
            node {
                use _ =
                    Activity.start
                        "ComputeParseAndCheckAllFilesInProject"
                        [| Activity.Tags.project, projectSnapshot.ProjectFileName |> Path.GetFileName |]

                let! projectSnapshot = parseSourceFiles projectSnapshot bootstrapInfo.TcConfig

                let! graph, dependencyFiles = ComputeDependencyGraphForProject bootstrapInfo.TcConfig projectSnapshot

                return!
                    processTypeCheckingGraph
                        graph
                        (processGraphNode projectSnapshot bootstrapInfo dependencyFiles true)
                        bootstrapInfo.InitialTcInfo
                    |> NodeCode.AwaitAsync
            }
        )

    let ComputeProjectExtras (bootstrapInfo: BootstrapInfo) (projectSnapshot: ProjectSnapshotWithSources) =
        caches.ProjectExtras.Get(
            projectSnapshot.SignatureKey,
            node {

                let! results, finalInfo = ComputeParseAndCheckAllFilesInProject bootstrapInfo projectSnapshot

                let assemblyName = bootstrapInfo.AssemblyName
                let tcConfig = bootstrapInfo.TcConfig
                let tcGlobals = bootstrapInfo.TcGlobals

                let results = results |> Seq.sortBy fst |> Seq.map snd |> Seq.toList

                // Finish the checking
                let (_tcEnvAtEndOfLastFile, topAttrs, checkedImplFiles, _), tcState =
                    CheckMultipleInputsFinish(results, finalInfo.tcState)

                let tcState, _, ccuContents = CheckClosedInputSetFinish([], tcState)

                let generatedCcu = tcState.Ccu.CloneWithFinalizedContents(ccuContents)

                // Compute the identity of the generated assembly based on attributes, options etc.
                // Some of this is duplicated from fsc.fs
                let ilAssemRef =
                    let publicKey =
                        try
                            let signingInfo = ValidateKeySigningAttributes(tcConfig, tcGlobals, topAttrs)

                            match GetStrongNameSigner signingInfo with
                            | None -> None
                            | Some s -> Some(PublicKey.KeyAsToken(s.PublicKey))
                        with exn ->
                            errorRecoveryNoRange exn
                            None

                    let locale =
                        TryFindFSharpStringAttribute
                            tcGlobals
                            (tcGlobals.FindSysAttrib "System.Reflection.AssemblyCultureAttribute")
                            topAttrs.assemblyAttrs

                    let assemVerFromAttrib =
                        TryFindFSharpStringAttribute
                            tcGlobals
                            (tcGlobals.FindSysAttrib "System.Reflection.AssemblyVersionAttribute")
                            topAttrs.assemblyAttrs
                        |> Option.bind (fun v ->
                            try
                                Some(parseILVersion v)
                            with _ ->
                                None)

                    let ver =
                        match assemVerFromAttrib with
                        | None -> tcConfig.version.GetVersionInfo(tcConfig.implicitIncludeDir)
                        | Some v -> v

                    ILAssemblyRef.Create(assemblyName, None, publicKey, false, Some ver, locale)

                let assemblyDataResult =
                    try
                        // Assemblies containing type provider components can not successfully be used via cross-assembly references.
                        // We return 'None' for the assembly portion of the cross-assembly reference
                        let hasTypeProviderAssemblyAttrib =
                            topAttrs.assemblyAttrs
                            |> List.exists (fun (Attrib(tcref, _, _, _, _, _, _)) ->
                                let nm = tcref.CompiledRepresentationForNamedType.BasicQualifiedName

                                nm = typeof<Microsoft.FSharp.Core.CompilerServices.TypeProviderAssemblyAttribute>.FullName)

                        if tcState.CreatesGeneratedProvidedTypes || hasTypeProviderAssemblyAttrib then
                            ProjectAssemblyDataResult.Unavailable true
                        else
                            ProjectAssemblyDataResult.Available(
                                RawFSharpAssemblyDataBackedByLanguageService(
                                    bootstrapInfo.TcConfig,
                                    bootstrapInfo.TcGlobals,
                                    generatedCcu,
                                    bootstrapInfo.OutFile,
                                    topAttrs,
                                    bootstrapInfo.AssemblyName,
                                    ilAssemRef
                                )
                                :> IRawFSharpAssemblyData
                            )
                    with exn ->
                        errorRecoveryNoRange exn
                        ProjectAssemblyDataResult.Unavailable true

                return finalInfo, ilAssemRef, assemblyDataResult, checkedImplFiles
            }
        )

    let ComputeAssemblyData (projectSnapshot: ProjectSnapshot) fileName =
        caches.AssemblyData.Get(
            projectSnapshot.SignatureKey,
            node {

                try

                    let availableOnDiskModifiedTime =
                        if FileSystem.FileExistsShim fileName then
                            Some <| FileSystem.GetLastWriteTimeShim fileName
                        else
                            None

                    // TODO: This kinda works, but the problem is that in order to switch a project to "in-memory" mode
                    //  - some file needs to be edited (this tirggers a re-check, but LastModifiedTimeOnDisk won't change)
                    //  - saved (this will not trigger anything)
                    //  - and then another change has to be made (to any file buffer) - so that recheck is triggered and we get here again
                    // Until that sequence happens the project will be used from disk (if available).
                    // To get around it we probably need to detect changes made in the editor and record a timestamp for them.
                    let shouldUseOnDisk =
                        availableOnDiskModifiedTime
                        |> Option.exists (fun t -> t >= projectSnapshot.GetLastModifiedTimeOnDisk())

                    let name = projectSnapshot.ProjectFileName |> Path.GetFileNameWithoutExtension

                    if shouldUseOnDisk then
                        Trace.TraceInformation($"Using assembly on disk: {name}")
                        return ProjectAssemblyDataResult.Unavailable true
                    else
                        match! ComputeBootstrapInfo projectSnapshot with
                        | None, _ ->
                            Trace.TraceInformation($"Using assembly on disk (unintentionally): {name}")
                            return ProjectAssemblyDataResult.Unavailable true
                        | Some bootstrapInfo, _creationDiags ->

                            let! snapshotWithSources = LoadSources bootstrapInfo projectSnapshot

                            let! _, _, assemblyDataResult, _ = ComputeProjectExtras bootstrapInfo snapshotWithSources
                            Trace.TraceInformation($"Using in-memory project reference: {name}")

                            return assemblyDataResult
                with
                | TaskCancelled ex -> return raise ex
                | ex ->
                    errorR (exn ($"Error while computing assembly data for project {projectSnapshot.Label}: {ex}"))
                    return ProjectAssemblyDataResult.Unavailable true
            }
        )

    let ComputeParseAndCheckProject (projectSnapshot: ProjectSnapshot) =
        caches.ParseAndCheckProject.Get(
            projectSnapshot.FullKey,
            node {

                match! ComputeBootstrapInfo projectSnapshot with
                | None, creationDiags ->
                    return FSharpCheckProjectResults(projectSnapshot.ProjectFileName, None, keepAssemblyContents, creationDiags, None)
                | Some bootstrapInfo, creationDiags ->

                    let! snapshotWithSources = LoadSources bootstrapInfo projectSnapshot

                    let! tcInfo, ilAssemRef, assemblyDataResult, checkedImplFiles = ComputeProjectExtras bootstrapInfo snapshotWithSources

                    let diagnosticsOptions = bootstrapInfo.TcConfig.diagnosticsOptions
                    let fileName = DummyFileNameForRangesWithoutASpecificLocation

                    let topAttribs = tcInfo.topAttribs
                    let tcState = tcInfo.tcState
                    let tcEnvAtEnd = tcInfo.tcEnvAtEndOfFile
                    let tcDiagnostics = tcInfo.TcDiagnostics
                    let tcDependencyFiles = tcInfo.tcDependencyFiles

                    let symbolEnv =
                        SymbolEnv(bootstrapInfo.TcGlobals, tcInfo.tcState.Ccu, Some tcInfo.tcState.CcuSig, bootstrapInfo.TcImports)
                        |> Some

                    let tcDiagnostics =
                        DiagnosticHelpers.CreateDiagnostics(
                            diagnosticsOptions,
                            true,
                            fileName,
                            tcDiagnostics,
                            suggestNamesForErrors,
                            bootstrapInfo.TcConfig.flatErrors,
                            symbolEnv
                        )

                    let diagnostics = [| yield! creationDiags; yield! tcDiagnostics |]

                    let getAssemblyData () =
                        match assemblyDataResult with
                        | ProjectAssemblyDataResult.Available data -> Some data
                        | _ -> None

                    let symbolUses =
                        tcInfo.sink |> Seq.rev |> Seq.map (fun sink -> sink.GetSymbolUses())

                    let details =
                        (bootstrapInfo.TcGlobals,
                         bootstrapInfo.TcImports,
                         tcState.Ccu,
                         tcState.CcuSig,
                         Choice2Of2(async.Return symbolUses),
                         topAttribs,
                         getAssemblyData,
                         ilAssemRef,
                         tcEnvAtEnd.AccessRights,
                         Some checkedImplFiles,
                         Array.ofList tcDependencyFiles,
                         projectSnapshot.ToOptions())

                    let results =
                        FSharpCheckProjectResults(
                            projectSnapshot.ProjectFileName,
                            Some bootstrapInfo.TcConfig,
                            keepAssemblyContents,
                            diagnostics,
                            Some details
                        )

                    return results
            }
        )

    let tryGetSink (fileName: string) (projectSnapshot: ProjectSnapshot) =
        node {
            match! ComputeBootstrapInfo projectSnapshot with
            | None, _ -> return None
            | Some bootstrapInfo, _creationDiags ->

                let! snapshotWithSources = projectSnapshot.UpTo fileName |> LoadSources bootstrapInfo

                let! _, tcInfo = ComputeTcLastFile bootstrapInfo snapshotWithSources

                return tcInfo.sink |> List.tryHead |> Option.map (fun sink -> sink, bootstrapInfo)
        }

    let ComputeSemanticClassification (fileName: string, projectSnapshot: ProjectSnapshot) =
        caches.SemanticClassification.Get(
            projectSnapshot.FileKey fileName,
            node {
                use _ =
                    Activity.start "ComputeSemanticClassification" [| Activity.Tags.fileName, fileName |> Path.GetFileName |]

                let! sinkOpt = tryGetSink fileName projectSnapshot

                return
                    sinkOpt
                    |> Option.bind (fun (sink, bootstrapInfo) ->
                        let sResolutions = sink.GetResolutions()

                        let semanticClassification =
                            sResolutions.GetSemanticClassification(
                                bootstrapInfo.TcGlobals,
                                bootstrapInfo.TcImports.GetImportMap(),
                                sink.GetFormatSpecifierLocations(),
                                None
                            )

                        let sckBuilder = SemanticClassificationKeyStoreBuilder()
                        sckBuilder.WriteAll semanticClassification

                        sckBuilder.TryBuildAndReset())
                    |> Option.map (fun sck -> sck.GetView())
            }
        )

    let ComputeItemKeyStore (fileName: string, projectSnapshot: ProjectSnapshot) =
        caches.ItemKeyStore.Get(
            projectSnapshot.FileKey fileName,
            node {
                use _ =
                    Activity.start "ComputeItemKeyStore" [| Activity.Tags.fileName, fileName |> Path.GetFileName |]

                let! sinkOpt = tryGetSink fileName projectSnapshot

                return
                    sinkOpt
                    |> Option.bind (fun (sink, { TcGlobals = g }) ->
                        let sResolutions = sink.GetResolutions()

                        let builder = ItemKeyStoreBuilder(g)

                        let preventDuplicates =
                            HashSet(
                                { new IEqualityComparer<struct (pos * pos)> with
                                    member _.Equals((s1, e1): struct (pos * pos), (s2, e2): struct (pos * pos)) =
                                        Position.posEq s1 s2 && Position.posEq e1 e2

                                    member _.GetHashCode o = o.GetHashCode()
                                }
                            )

                        sResolutions.CapturedNameResolutions
                        |> Seq.iter (fun cnr ->
                            let r = cnr.Range

                            if preventDuplicates.Add struct (r.Start, r.End) then
                                builder.Write(cnr.Range, cnr.Item))

                        builder.TryBuildAndReset())
            }
        )

    member _.ParseFile(fileName, projectSnapshot: ProjectSnapshot, _userOpName) =
        node {
            //use _ =
            //    Activity.start "ParseFile" [| Activity.Tags.fileName, fileName |> Path.GetFileName |]

            // TODO: might need to deal with exceptions here:
            let tcConfigB, sourceFileNames, _ = ComputeTcConfigBuilder projectSnapshot

            let tcConfig = TcConfig.Create(tcConfigB, validate = true)

            let _index, fileSnapshot =
                projectSnapshot.SourceFiles
                |> Seq.mapi pair
                |> Seq.tryFind (fun (_, f) -> f.FileName = fileName)
                |> Option.defaultWith (fun () -> failwith $"File not found: {fileName}")

            let isExe = tcConfig.target.IsExe
            let isLastCompiland = fileName = (sourceFileNames |> List.last)

            let! file = LoadSource fileSnapshot isExe isLastCompiland
            let! parseResult = getParseResult projectSnapshot Seq.empty file tcConfig
            return parseResult
        }

    member _.ParseAndCheckFileInProject(fileName: string, projectSnapshot: ProjectSnapshot, userOpName: string) =
        ignore userOpName
        ComputeParseAndCheckFileInProject fileName projectSnapshot

    member _.FindReferencesInFile(fileName: string, projectSnapshot: ProjectSnapshot, symbol: FSharpSymbol, userOpName: string) =
        ignore userOpName

        node {
            match! ComputeItemKeyStore(fileName, projectSnapshot) with
            | None -> return Seq.empty
            | Some itemKeyStore -> return itemKeyStore.FindAll symbol.Item
        }

    member _.GetAssemblyData(projectSnapshot: ProjectSnapshot, fileName, _userOpName) =
        ComputeAssemblyData projectSnapshot fileName

    member _.Caches = caches

    member _.SetCacheSizeFactor(sizeFactor: int) =
        if sizeFactor <> caches.SizeFactor then
            caches <- CompilerCaches(sizeFactor)

    interface IBackgroundCompiler with

        member this.CheckFileInProject
            (
                parseResults: FSharpParseFileResults,
                fileName: string,
                fileVersion: int,
                sourceText: ISourceText,
                options: FSharpProjectOptions,
                userOpName: string
            ) : NodeCode<FSharpCheckFileAnswer> =
            node {
                let! snapshot =
                    FSharpProjectSnapshot.FromOptions(options, fileName, fileVersion, sourceText)
                    |> NodeCode.AwaitAsync

                ignore parseResults

                let! _, result = this.ParseAndCheckFileInProject(fileName, snapshot.ProjectSnapshot, userOpName)

                return result
            }

        member this.CheckFileInProjectAllowingStaleCachedResults
            (
                parseResults: FSharpParseFileResults,
                fileName: string,
                fileVersion: int,
                sourceText: ISourceText,
                options: FSharpProjectOptions,
                userOpName: string
            ) : NodeCode<FSharpCheckFileAnswer option> =
            node {
                let! snapshot =
                    FSharpProjectSnapshot.FromOptions(options, fileName, fileVersion, sourceText)
                    |> NodeCode.AwaitAsync

                ignore parseResults

                let! _, result = this.ParseAndCheckFileInProject(fileName, snapshot.ProjectSnapshot, userOpName)

                return Some result
            }

        member this.ClearCache(projects: FSharpProjectIdentifier seq, userOpName: string) : unit =
            use _ =
                Activity.start "TransparentCompiler.ClearCache" [| Activity.Tags.userOpName, userOpName |]

            this.Caches.Clear(
                projects
                |> Seq.map (function
                    | FSharpProjectIdentifier(x, y) -> (x, y))
                |> Set
            )

        member this.ClearCache(options: seq<FSharpProjectOptions>, userOpName: string) : unit =
            use _ =
                Activity.start "TransparentCompiler.ClearCache" [| Activity.Tags.userOpName, userOpName |]

            backgroundCompiler.ClearCache(options, userOpName)
            this.Caches.Clear(options |> Seq.map (fun o -> o.GetProjectIdentifier()) |> Set)

        member _.ClearCaches() : unit =
            backgroundCompiler.ClearCaches()
            caches <- CompilerCaches(100) // TODO: check

        member _.DownsizeCaches() : unit = backgroundCompiler.DownsizeCaches()

        member _.BeforeBackgroundFileCheck = beforeFileChecked.Publish

        member _.FileParsed = fileParsed.Publish

        member _.FileChecked = fileChecked.Publish

        member _.ProjectChecked = projectChecked.Publish

        member this.FindReferencesInFile
            (
                fileName: string,
                options: FSharpProjectOptions,
                symbol: FSharpSymbol,
                canInvalidateProject: bool,
                userOpName: string
            ) : NodeCode<seq<range>> =
            node {
                ignore canInvalidateProject
                let! snapshot = FSharpProjectSnapshot.FromOptions options |> NodeCode.AwaitAsync

                return! this.FindReferencesInFile(fileName, snapshot.ProjectSnapshot, symbol, userOpName)
            }

        member this.FindReferencesInFile(fileName, projectSnapshot, symbol, userOpName) =
            this.FindReferencesInFile(fileName, projectSnapshot.ProjectSnapshot, symbol, userOpName)

        member _.FrameworkImportsCache: FrameworkImportsCache =
            backgroundCompiler.FrameworkImportsCache

        member this.GetAssemblyData(options: FSharpProjectOptions, fileName, userOpName: string) : NodeCode<ProjectAssemblyDataResult> =
            node {
                let! snapshot = FSharpProjectSnapshot.FromOptions options |> NodeCode.AwaitAsync
                return! this.GetAssemblyData(snapshot.ProjectSnapshot, fileName, userOpName)
            }

        member this.GetAssemblyData
            (
                projectSnapshot: FSharpProjectSnapshot,
                fileName,
                userOpName: string
            ) : NodeCode<ProjectAssemblyDataResult> =
            this.GetAssemblyData(projectSnapshot.ProjectSnapshot, fileName, userOpName)

        member this.GetBackgroundCheckResultsForFileInProject
            (
                fileName: string,
                options: FSharpProjectOptions,
                userOpName: string
            ) : NodeCode<FSharpParseFileResults * FSharpCheckFileResults> =
            node {
                let! snapshot = FSharpProjectSnapshot.FromOptions options |> NodeCode.AwaitAsync

                match! this.ParseAndCheckFileInProject(fileName, snapshot.ProjectSnapshot, userOpName) with
                | parseResult, FSharpCheckFileAnswer.Succeeded checkResult -> return parseResult, checkResult
                | parseResult, FSharpCheckFileAnswer.Aborted -> return parseResult, FSharpCheckFileResults.MakeEmpty(fileName, [||], true)
            }

        member this.GetBackgroundParseResultsForFileInProject
            (
                fileName: string,
                options: FSharpProjectOptions,
                userOpName: string
            ) : NodeCode<FSharpParseFileResults> =
            node {
                let! snapshot = FSharpProjectSnapshot.FromOptions options |> NodeCode.AwaitAsync
                return! this.ParseFile(fileName, snapshot.ProjectSnapshot, userOpName)
            }

        member this.GetCachedCheckFileResult
            (
                builder: IncrementalBuilder,
                fileName: string,
                sourceText: ISourceText,
                options: FSharpProjectOptions
            ) : NodeCode<(FSharpParseFileResults * FSharpCheckFileResults) option> =
            node {
                ignore builder

                let! snapshot =
                    FSharpProjectSnapshot.FromOptions(options, fileName, 1, sourceText)
                    |> NodeCode.AwaitAsync

                match! this.ParseAndCheckFileInProject(fileName, snapshot.ProjectSnapshot, "GetCachedCheckFileResult") with
                | parseResult, FSharpCheckFileAnswer.Succeeded checkResult -> return Some(parseResult, checkResult)
                | _, FSharpCheckFileAnswer.Aborted -> return None
            }

        member this.GetProjectOptionsFromScript
            (
                fileName: string,
                sourceText: ISourceText,
                previewEnabled: bool option,
                loadedTimeStamp: DateTime option,
                otherFlags: string array option,
                useFsiAuxLib: bool option,
                useSdkRefs: bool option,
                sdkDirOverride: string option,
                assumeDotNetFramework: bool option,
                optionsStamp: int64 option,
                userOpName: string
            ) : Async<FSharpProjectOptions * FSharpDiagnostic list> =
            backgroundCompiler.GetProjectOptionsFromScript(
                fileName,
                sourceText,
                previewEnabled,
                loadedTimeStamp,
                otherFlags,
                useFsiAuxLib,
                useSdkRefs,
                sdkDirOverride,
                assumeDotNetFramework,
                optionsStamp,
                userOpName
            )

        member this.GetSemanticClassificationForFile(fileName: string, snapshot: FSharpProjectSnapshot, userOpName: string) =
            node {
                ignore userOpName
                return! ComputeSemanticClassification(fileName, snapshot.ProjectSnapshot)
            }

        member this.GetSemanticClassificationForFile
            (
                fileName: string,
                options: FSharpProjectOptions,
                userOpName: string
            ) : NodeCode<EditorServices.SemanticClassificationView option> =
            node {
                ignore userOpName
                let! snapshot = FSharpProjectSnapshot.FromOptions options |> NodeCode.AwaitAsync
                return! ComputeSemanticClassification(fileName, snapshot.ProjectSnapshot)
            }

        member this.InvalidateConfiguration(options: FSharpProjectOptions, userOpName: string) : unit =
            backgroundCompiler.InvalidateConfiguration(options, userOpName)

        member this.NotifyFileChanged(fileName: string, options: FSharpProjectOptions, userOpName: string) : NodeCode<unit> =
            backgroundCompiler.NotifyFileChanged(fileName, options, userOpName)

        member this.NotifyProjectCleaned(options: FSharpProjectOptions, userOpName: string) : Async<unit> =
            backgroundCompiler.NotifyProjectCleaned(options, userOpName)

        member this.ParseAndCheckFileInProject
            (
                fileName: string,
                fileVersion: int,
                sourceText: ISourceText,
                options: FSharpProjectOptions,
                userOpName: string
            ) : NodeCode<FSharpParseFileResults * FSharpCheckFileAnswer> =
            node {
                let! snapshot =
                    FSharpProjectSnapshot.FromOptions(options, fileName, fileVersion, sourceText)
                    |> NodeCode.AwaitAsync

                return! this.ParseAndCheckFileInProject(fileName, snapshot.ProjectSnapshot, userOpName)
            }

        member this.ParseAndCheckFileInProject(fileName: string, projectSnapshot: FSharpProjectSnapshot, userOpName: string) =
            this.ParseAndCheckFileInProject(fileName, projectSnapshot.ProjectSnapshot, userOpName)

        member this.ParseAndCheckProject(options: FSharpProjectOptions, userOpName: string) : NodeCode<FSharpCheckProjectResults> =
            node {
                ignore userOpName
                let! snapshot = FSharpProjectSnapshot.FromOptions options |> NodeCode.AwaitAsync
                return! ComputeParseAndCheckProject snapshot.ProjectSnapshot
            }

        member this.ParseAndCheckProject(projectSnapshot: FSharpProjectSnapshot, userOpName: string) : NodeCode<FSharpCheckProjectResults> =
            node {
                ignore userOpName
                return! ComputeParseAndCheckProject projectSnapshot.ProjectSnapshot
            }

        member this.ParseFile(fileName, projectSnapshot, userOpName) =
            this.ParseFile(fileName, projectSnapshot.ProjectSnapshot, userOpName)
            |> Async.AwaitNodeCode

        member this.ParseFile
            (
                fileName: string,
                sourceText: ISourceText,
                options: FSharpParsingOptions,
                cache: bool,
                flatErrors: bool,
                userOpName: string
            ) =
            backgroundCompiler.ParseFile(fileName, sourceText, options, cache, flatErrors, userOpName)

        member this.TryGetRecentCheckResultsForFile
            (
                fileName: string,
                options: FSharpProjectOptions,
                sourceText: ISourceText option,
                userOpName: string
            ) : (FSharpParseFileResults * FSharpCheckFileResults * SourceTextHash) option =
            backgroundCompiler.TryGetRecentCheckResultsForFile(fileName, options, sourceText, userOpName)