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Compiler Services: Project Analysis

This tutorial demonstrates how to can analyze a whole project using services provided by the F# compiler.

NOTE: The FSharp.Compiler.Service API is subject to change when later versions of the nuget package are published.

Getting whole-project results

As in the previous tutorial (using untyped AST), we start by referencing FSharp.Compiler.Service.dll, opening the relevant namespace and creating an instance of InteractiveChecker:

// Reference F# compiler API
#r "FSharp.Compiler.Service.dll"

open System
open System.Collections.Generic
open FSharp.Compiler.SourceCodeServices
open FSharp.Compiler.Text

// Create an interactive checker instance
let checker = FSharpChecker.Create()

Here are our sample inputs:

module Inputs =
    open System.IO

    let base1 = Path.GetTempFileName()
    let fileName1 = Path.ChangeExtension(base1, ".fs")
    let base2 = Path.GetTempFileName()
    let fileName2 = Path.ChangeExtension(base2, ".fs")
    let dllName = Path.ChangeExtension(base2, ".dll")
    let projFileName = Path.ChangeExtension(base2, ".fsproj")
    let fileSource1 = """
module M

type C() =
    member x.P = 1

let xxx = 3 + 4
let fff () = xxx + xxx
    """
    File.WriteAllText(fileName1, fileSource1)

    let fileSource2 = """
module N

open M

type D1() =
    member x.SomeProperty = M.xxx

type D2() =
    member x.SomeProperty = M.fff() + D1().P

// Generate a warning
let y2 = match 1 with 1 -> M.xxx
    """
    File.WriteAllText(fileName2, fileSource2)

We use GetProjectOptionsFromCommandLineArgs to treat two files as a project:

let projectOptions =
    let sysLib nm =
        if System.Environment.OSVersion.Platform = System.PlatformID.Win32NT then
            // file references only valid on Windows
            System.Environment.GetFolderPath(System.Environment.SpecialFolder.ProgramFilesX86) +
            @"\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\" + nm + ".dll"
        else
            let sysDir = System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory()
            let (++) a b = System.IO.Path.Combine(a,b)
            sysDir ++ nm + ".dll"

    let fsCore4300() =
        if System.Environment.OSVersion.Platform = System.PlatformID.Win32NT then
            // file references only valid on Windows
            System.Environment.GetFolderPath(System.Environment.SpecialFolder.ProgramFilesX86) +
            @"\Reference Assemblies\Microsoft\FSharp\.NETFramework\v4.0\4.3.0.0\FSharp.Core.dll"
        else
            sysLib "FSharp.Core"

    checker.GetProjectOptionsFromCommandLineArgs
       (Inputs.projFileName,
        [| yield "--simpleresolution"
           yield "--noframework"
           yield "--debug:full"
           yield "--define:DEBUG"
           yield "--optimize-"
           yield "--out:" + Inputs.dllName
           yield "--doc:test.xml"
           yield "--warn:3"
           yield "--fullpaths"
           yield "--flaterrors"
           yield "--target:library"
           yield Inputs.fileName1
           yield Inputs.fileName2
           let references =
             [ sysLib "mscorlib"
               sysLib "System"
               sysLib "System.Core"
               fsCore4300() ]
           for r in references do
                 yield "-r:" + r |])

Now check the entire project (using the files saved on disk):

let wholeProjectResults = checker.ParseAndCheckProject(projectOptions) |> Async.RunSynchronously

Now look at the errors and warnings:

wholeProjectResults .Errors.Length // 1
wholeProjectResults.Errors.[0].Message.Contains("Incomplete pattern matches on this expression") // yes it does

wholeProjectResults.Errors.[0].StartLineAlternate // 13
wholeProjectResults.Errors.[0].EndLineAlternate // 13
wholeProjectResults.Errors.[0].StartColumn // 15
wholeProjectResults.Errors.[0].EndColumn // 16

Now look at the inferred signature for the project:

[ for x in wholeProjectResults.AssemblySignature.Entities -> x.DisplayName ] // ["N"; "M"]
[ for x in wholeProjectResults.AssemblySignature.Entities.[0].NestedEntities -> x.DisplayName ] // ["D1"; "D2"]
[ for x in wholeProjectResults.AssemblySignature.Entities.[1].NestedEntities -> x.DisplayName ] // ["C"]
[ for x in wholeProjectResults.AssemblySignature.Entities.[0].MembersFunctionsAndValues -> x.DisplayName ] // ["y"; "y2"]

You can also get all symbols in the project:

let rec allSymbolsInEntities (entities: IList<FSharpEntity>) =
    [ for e in entities do
          yield (e :> FSharpSymbol)
          for x in e.MembersFunctionsAndValues do
             yield (x :> FSharpSymbol)
          for x in e.UnionCases do
             yield (x :> FSharpSymbol)
          for x in e.FSharpFields do
             yield (x :> FSharpSymbol)
          yield! allSymbolsInEntities e.NestedEntities ]

let allSymbols = allSymbolsInEntities wholeProjectResults.AssemblySignature.Entities

After checking the whole project, you can access the background results for individual files in the project. This will be fast and will not involve any additional checking.

let backgroundParseResults1, backgroundTypedParse1 =
    checker.GetBackgroundCheckResultsForFileInProject(Inputs.fileName1, projectOptions)
    |> Async.RunSynchronously

You can now resolve symbols in each file:

let xSymbolUseOpt =
    backgroundTypedParse1.GetSymbolUseAtLocation(9,9,"",["xxx"])
    |> Async.RunSynchronously

let xSymbolUse = xSymbolUseOpt.Value

let xSymbol = xSymbolUse.Symbol

You can find out more about a symbol by doing type checks on various symbol kinds:

let xSymbolAsValue =
    match xSymbol with
    | :? FSharpMemberOrFunctionOrValue as xSymbolAsVal -> xSymbolAsVal
    | _ -> failwith "we expected this to be a member, function or value"

For each symbol, you can look up the references to that symbol:

let usesOfXSymbol =
    wholeProjectResults.GetUsesOfSymbol(xSymbol)
    |> Async.RunSynchronously

You can iterate all the defined symbols in the inferred signature and find where they are used:

let allUsesOfAllSignatureSymbols =
    [ for s in allSymbols do
         let uses = wholeProjectResults.GetUsesOfSymbol(s) |> Async.RunSynchronously
         yield s.ToString(), uses ]

You can also look at all the symbols uses in the whole project (including uses of symbols with local scope)

let allUsesOfAllSymbols =
    wholeProjectResults.GetAllUsesOfAllSymbols()
    |> Async.RunSynchronously

You can also request checks of updated versions of files within the project (note that the other files in the project are still read from disk, unless you are using the FileSystem API):

let parseResults1, checkAnswer1 =
    checker.ParseAndCheckFileInProject(Inputs.fileName1, 0, SourceText.ofString Inputs.fileSource1, projectOptions)
    |> Async.RunSynchronously

let checkResults1 =
    match checkAnswer1 with
    | FSharpCheckFileAnswer.Succeeded x ->  x
    | _ -> failwith "unexpected aborted"

let parseResults2, checkAnswer2 =
    checker.ParseAndCheckFileInProject(Inputs.fileName2, 0, SourceText.ofString Inputs.fileSource2, projectOptions)
    |> Async.RunSynchronously

let checkResults2 =
    match checkAnswer2 with
    | FSharpCheckFileAnswer.Succeeded x ->  x
    | _ -> failwith "unexpected aborted"

Again, you can resolve symbols and ask for references:

let xSymbolUse2Opt =
    checkResults1.GetSymbolUseAtLocation(9,9,"",["xxx"])
    |> Async.RunSynchronously

let xSymbolUse2 = xSymbolUse2Opt.Value

let xSymbol2 = xSymbolUse2.Symbol

let usesOfXSymbol2 =
    wholeProjectResults.GetUsesOfSymbol(xSymbol2)
    |> Async.RunSynchronously

Or ask for all the symbols uses in the file (including uses of symbols with local scope)

let allUsesOfAllSymbolsInFile1 =
    checkResults1.GetAllUsesOfAllSymbolsInFile()
    |> Async.RunSynchronously

Or ask for all the uses of one symbol in one file:

let allUsesOfXSymbolInFile1 =
    checkResults1.GetUsesOfSymbolInFile(xSymbol2)
    |> Async.RunSynchronously

let allUsesOfXSymbolInFile2 =
    checkResults2.GetUsesOfSymbolInFile(xSymbol2)
    |> Async.RunSynchronously

Analyzing multiple projects

If you have multiple F# projects to analyze which include references from some projects to others, then the simplest way to do this is to build the projects and specify the cross-project references using a -r:path-to-output-of-project.dll argument in the ProjectOptions. However, this requires the build of each project to succeed, producing the DLL file on disk which can be referred to.

In some situations, e.g. in an IDE, you may wish to allow references to other F# projects prior to successful compilation to a DLL. To do this, fill in the ProjectReferences entry in ProjectOptions, which recursively specifies the project options for dependent projects. Each project reference still needs a corresponding -r:path-to-output-of-project.dll command line argument in ProjectOptions, along with an entry in ProjectReferences. The first element of each tuple in the ProjectReferences entry should be the DLL name, i.e. path-to-output-of-project.dll. This should be the same as the text used in the -r project reference.

When a project reference is used, the analysis will make use of the results of incremental analysis of the referenced F# project from source files, without requiring the compilation of these files to DLLs.

To efficiently analyze a set of F# projects which include cross-references, you should populate the ProjectReferences correctly and then analyze each project in turn.

NOTE: Project references are disabled if the assembly being referred to contains type provider components - specifying the project reference will have no effect beyond forcing the analysis of the project, and the DLL will still be required on disk.

Summary

As you have seen, the ParseAndCheckProject lets you access results of project-wide analysis such as symbol references. To learn more about working with symbols, see Symbols.

Using the FSharpChecker component in multi-project, incremental and interactive editing situations may involve knowledge of the FSharpChecker operations queue and the FSharpChecker caches.

namespace System
namespace System.Collections
namespace System.Collections.Generic
Multiple items
namespace FSharp

--------------------
namespace Microsoft.FSharp
namespace FSharp.Compiler
namespace FSharp.Compiler.SourceCodeServices
Multiple items
namespace FSharp

--------------------
namespace Microsoft.FSharp

--------------------
type FSharpAttribute =
  member Format : context:FSharpDisplayContext -> string
  member AttributeType : FSharpEntity
  member ConstructorArguments : IList<FSharpType * obj>
  member IsUnresolved : bool
  member NamedArguments : IList<FSharpType * string * bool * obj>
namespace FSharp.Compiler.Text
val checker : FSharpChecker
type FSharpChecker =
  member CheckFileInProject : parsed:FSharpParseFileResults * filename:string * fileversion:int * sourceText:ISourceText * options:FSharpProjectOptions * ?textSnapshotInfo:obj * ?userOpName:string -> Async<FSharpCheckFileAnswer>
  member CheckProjectInBackground : options:FSharpProjectOptions * ?userOpName:string -> unit
  member ClearLanguageServiceRootCachesAndCollectAndFinalizeAllTransients : unit -> unit
  member Compile : argv:string [] * ?userOpName:string -> Async<FSharpErrorInfo [] * int>
  member Compile : ast:ParsedInput list * assemblyName:string * outFile:string * dependencies:string list * ?pdbFile:string * ?executable:bool * ?noframework:bool * ?userOpName:string -> Async<FSharpErrorInfo [] * int>
  member CompileToDynamicAssembly : otherFlags:string [] * execute:(TextWriter * TextWriter) option * ?userOpName:string -> Async<FSharpErrorInfo [] * int * Assembly option>
  member CompileToDynamicAssembly : ast:ParsedInput list * assemblyName:string * dependencies:string list * execute:(TextWriter * TextWriter) option * ?debug:bool * ?noframework:bool * ?userOpName:string -> Async<FSharpErrorInfo [] * int * Assembly option>
  member FindBackgroundReferencesInFile : filename:string * options:FSharpProjectOptions * symbol:FSharpSymbol * ?userOpName:string -> Async<seq<range>>
  member GetBackgroundCheckResultsForFileInProject : filename:string * options:FSharpProjectOptions * ?userOpName:string -> Async<FSharpParseFileResults * FSharpCheckFileResults>
  member GetBackgroundParseResultsForFileInProject : filename:string * options:FSharpProjectOptions * ?userOpName:string -> Async<FSharpParseFileResults>
  ...
static member FSharpChecker.Create : ?projectCacheSize:int * ?keepAssemblyContents:bool * ?keepAllBackgroundResolutions:bool * ?legacyReferenceResolver:FSharp.Compiler.ReferenceResolver.Resolver * ?tryGetMetadataSnapshot:FSharp.Compiler.AbstractIL.ILBinaryReader.ILReaderTryGetMetadataSnapshot * ?suggestNamesForErrors:bool * ?keepAllBackgroundSymbolUses:bool * ?enableBackgroundItemKeyStoreAndSemanticClassification:bool -> FSharpChecker
namespace System.IO
val base1 : string
type Path =
  static val DirectorySeparatorChar : char
  static val AltDirectorySeparatorChar : char
  static val VolumeSeparatorChar : char
  static val PathSeparator : char
  static val InvalidPathChars : char[]
  static member ChangeExtension : path:string * extension:string -> string
  static member Combine : [<ParamArray>] paths:string[] -> string + 3 overloads
  static member EndsInDirectorySeparator : path:ReadOnlySpan<char> -> bool + 1 overload
  static member GetDirectoryName : path:string -> string + 1 overload
  static member GetExtension : path:string -> string + 1 overload
  ...
Path.GetTempFileName() : string
val fileName1 : string
Path.ChangeExtension(path: string, extension: string) : string
val base2 : string
val fileName2 : string
val dllName : string
val projFileName : string
val fileSource1 : string
type File =
  static member AppendAllLines : path:string * contents:IEnumerable<string> -> unit + 1 overload
  static member AppendAllLinesAsync : path:string * contents:IEnumerable<string> * ?cancellationToken:CancellationToken -> Task + 1 overload
  static member AppendAllText : path:string * contents:string -> unit + 1 overload
  static member AppendAllTextAsync : path:string * contents:string * ?cancellationToken:CancellationToken -> Task + 1 overload
  static member AppendText : path:string -> StreamWriter
  static member Copy : sourceFileName:string * destFileName:string -> unit + 1 overload
  static member Create : path:string -> FileStream + 2 overloads
  static member CreateText : path:string -> StreamWriter
  static member Decrypt : path:string -> unit
  static member Delete : path:string -> unit
  ...
File.WriteAllText(path: string, contents: string) : unit
File.WriteAllText(path: string, contents: string, encoding: Text.Encoding) : unit
val fileSource2 : string
val projectOptions : FSharpProjectOptions
val sysLib : (string -> string)
val nm : string
type Environment =
  static member CommandLine : string
  static member CurrentDirectory : string with get, set
  static member CurrentManagedThreadId : int
  static member Exit : exitCode:int -> unit
  static member ExitCode : int with get, set
  static member ExpandEnvironmentVariables : name:string -> string
  static member FailFast : message:string -> unit + 2 overloads
  static member GetCommandLineArgs : unit -> string[]
  static member GetEnvironmentVariable : variable:string -> string + 1 overload
  static member GetEnvironmentVariables : unit -> IDictionary + 1 overload
  ...
  nested type SpecialFolder
  nested type SpecialFolderOption
property Environment.OSVersion: OperatingSystem with get
type PlatformID =
  | Win32S = 0
  | Win32Windows = 1
  | Win32NT = 2
  | WinCE = 3
  | Unix = 4
  | Xbox = 5
  | MacOSX = 6
field PlatformID.Win32NT: PlatformID = 2
Environment.GetFolderPath(folder: Environment.SpecialFolder) : string
Environment.GetFolderPath(folder: Environment.SpecialFolder, option: Environment.SpecialFolderOption) : string
type SpecialFolder =
  | ApplicationData = 26
  | CommonApplicationData = 35
  | LocalApplicationData = 28
  | Cookies = 33
  | Desktop = 0
  | Favorites = 6
  | History = 34
  | InternetCache = 32
  | Programs = 2
  | MyComputer = 17
  ...
field Environment.SpecialFolder.ProgramFilesX86: Environment.SpecialFolder = 42
val sysDir : string
namespace System.Runtime
namespace System.Runtime.InteropServices
type RuntimeEnvironment =
  static member FromGlobalAccessCache : a:Assembly -> bool
  static member GetRuntimeDirectory : unit -> string
  static member GetRuntimeInterfaceAsIntPtr : clsid:Guid * riid:Guid -> nativeint
  static member GetRuntimeInterfaceAsObject : clsid:Guid * riid:Guid -> obj
  static member GetSystemVersion : unit -> string
  static member SystemConfigurationFile : string
Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory() : string
val a : string
val b : string
IO.Path.Combine([<ParamArray>] paths: string []) : string
IO.Path.Combine(path1: string, path2: string) : string
IO.Path.Combine(path1: string, path2: string, path3: string) : string
IO.Path.Combine(path1: string, path2: string, path3: string, path4: string) : string
val fsCore4300 : (unit -> string)
module Inputs

from Project
val references : string list
val r : string
val wholeProjectResults : FSharpCheckProjectResults
Multiple items
type Async =
  static member AsBeginEnd : computation:('Arg -> Async<'T>) -> ('Arg * AsyncCallback * obj -> IAsyncResult) * (IAsyncResult -> 'T) * (IAsyncResult -> unit)
  static member AwaitEvent : event:IEvent<'Del,'T> * ?cancelAction:(unit -> unit) -> Async<'T> (requires delegate and 'Del :> Delegate)
  static member AwaitIAsyncResult : iar:IAsyncResult * ?millisecondsTimeout:int -> Async<bool>
  static member AwaitTask : task:Task -> Async<unit>
  static member AwaitTask : task:Task<'T> -> Async<'T>
  static member AwaitWaitHandle : waitHandle:WaitHandle * ?millisecondsTimeout:int -> Async<bool>
  static member CancelDefaultToken : unit -> unit
  static member Catch : computation:Async<'T> -> Async<Choice<'T,exn>>
  static member Choice : computations:seq<Async<'T option>> -> Async<'T option>
  static member FromBeginEnd : beginAction:(AsyncCallback * obj -> IAsyncResult) * endAction:(IAsyncResult -> 'T) * ?cancelAction:(unit -> unit) -> Async<'T>
  ...

--------------------
type Async<'T> =
static member Async.RunSynchronously : computation:Async<'T> * ?timeout:int * ?cancellationToken:Threading.CancellationToken -> 'T
val x : FSharpEntity
val x : FSharpMemberOrFunctionOrValue
val allSymbolsInEntities : entities:IList<FSharpEntity> -> FSharpSymbol list
val entities : IList<FSharpEntity>
type IList<'T> =
  inherit ICollection<'T>
  inherit IEnumerable<'T>
  inherit IEnumerable
  member IndexOf : item:'T -> int
  member Insert : index:int * item:'T -> unit
  member Item : int -> 'T with get, set
  member RemoveAt : index:int -> unit
type FSharpEntity =
  inherit FSharpSymbol
  private new : SymbolEnv * EntityRef -> FSharpEntity
  member AbbreviatedType : FSharpType
  member AccessPath : string
  member Accessibility : FSharpAccessibility
  member ActivePatternCases : FSharpActivePatternCase list
  member AllCompilationPaths : string list
  member AllInterfaces : IList<FSharpType>
  member ArrayRank : int
  member Attributes : IList<FSharpAttribute>
  ...
val e : FSharpEntity
type FSharpSymbol =
  member GetEffectivelySameAsHash : unit -> int
  member IsAccessible : FSharpAccessibilityRights -> bool
  member IsEffectivelySameAs : other:FSharpSymbol -> bool
  member Assembly : FSharpAssembly
  member DeclarationLocation : range option
  member DisplayName : string
  member FullName : string
  member ImplementationLocation : range option
  member IsExplicitlySuppressed : bool
  member private Item : Item
  ...
val x : FSharpUnionCase
val x : FSharpField
val allSymbols : FSharpSymbol list
val backgroundParseResults1 : FSharpParseFileResults
val backgroundTypedParse1 : FSharpCheckFileResults
val xSymbolUseOpt : FSharpSymbolUse option
val xSymbolUse : FSharpSymbolUse
val xSymbol : FSharpSymbol
val xSymbolAsValue : FSharpMemberOrFunctionOrValue
type FSharpMemberOrFunctionOrValue =
  inherit FSharpSymbol
  private new : SymbolEnv * MethInfo -> FSharpMemberOrFunctionOrValue
  private new : SymbolEnv * ValRef -> FSharpMemberOrFunctionOrValue
  member FormatLayout : context:FSharpDisplayContext -> Layout
  member Overloads : bool -> IList<FSharpMemberOrFunctionOrValue> option
  member Accessibility : FSharpAccessibility
  member ApparentEnclosingEntity : FSharpEntity
  member Attributes : IList<FSharpAttribute>
  member CompiledName : string
  member CurriedParameterGroups : IList<IList<FSharpParameter>>
  ...
val xSymbolAsVal : FSharpMemberOrFunctionOrValue
val failwith : message:string -> 'T
val usesOfXSymbol : FSharpSymbolUse []
val allUsesOfAllSignatureSymbols : (string * FSharpSymbolUse []) list
val s : FSharpSymbol
val uses : FSharpSymbolUse []
val allUsesOfAllSymbols : FSharpSymbolUse []
val parseResults1 : FSharpParseFileResults
val checkAnswer1 : FSharpCheckFileAnswer
module SourceText

from FSharp.Compiler.Text
val ofString : string -> ISourceText
val checkResults1 : FSharpCheckFileResults
type FSharpCheckFileAnswer =
  | Aborted
  | Succeeded of FSharpCheckFileResults
union case FSharpCheckFileAnswer.Succeeded: FSharpCheckFileResults -> FSharpCheckFileAnswer
val x : FSharpCheckFileResults
val parseResults2 : FSharpParseFileResults
val checkAnswer2 : FSharpCheckFileAnswer
val checkResults2 : FSharpCheckFileResults
val xSymbolUse2Opt : FSharpSymbolUse option
val xSymbolUse2 : FSharpSymbolUse
val xSymbol2 : FSharpSymbol
val usesOfXSymbol2 : FSharpSymbolUse []
val allUsesOfAllSymbolsInFile1 : FSharpSymbolUse []
val allUsesOfXSymbolInFile1 : FSharpSymbolUse []
val allUsesOfXSymbolInFile2 : FSharpSymbolUse []