Console.Out needs to be redirected to get FsiEvaluationSession output in correct order (was FCS 0.0.59 shows help at the end)

[forki]

After updating FAKE to FCS 0.0.59 (see fsprojects/FAKE#519) it shows the FSI help at the end of a script.
Any ideas why?
@tpetricek @dsyme @sergey-tihon

[sergey-tihon]

I also found this today in the response from FAKE.Deploy.

[dungpa]

Could it be the problem because you upgrade to Visual F# Tools 3.1.2? I started seeing it in AppVeyor builds after they upgraded to Visual F# Tools 3.1.2 https://ci.appveyor.com/project/dungpa/visualfsharppowertools/build/1.5.0-a1408251942.

[forki]

This would be even worse.
On Aug 25, 2014 10:28 PM, "Anh-Dung Phan" notifications@github.com wrote:

Could it be the problem because you upgrade to Visual F# Tools 3.1.2? I
started seeing it in AppVeyor builds after they upgrade to Visual F# Tools
3.1.2
https://ci.appveyor.com/project/dungpa/visualfsharppowertools/build/1.5.0-a1408251942
.

—
Reply to this email directly or view it on GitHub
#201 (comment)
.

[sergey-tihon]

@dungpa but your build script also use new version of FAKE 3.3.0 that built on top of FCS 0.0.59.

[dungpa]

You're right. My bad. I didn't notice that FAKE 3.3.0 has just been released today.

[forki]

Yes. It's probably the new FCS. Still weird issue
On Aug 25, 2014 11:13 PM, "Anh-Dung Phan" notifications@github.com wrote:

You're right. My bad. I didn't notice that FAKE 3.3.0 has just been
released today.

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#201 (comment)
.

[forki]

Now I think It's not FCS. It's probably fsprojects/FAKE@a364933#diff-ee58d9452be1f275ad4acc98277247a3R127

[sergey-tihon]

Ok... but without this line you do not get output in the case of success execution, don't it?
handleMessages catch output and show to the user. Since it is yellow - it is data from outStream...
I thought that it is OK that FAKE shows as all output, and question is why FCS prints this data into output stream. Am I right?

[forki]

mhm I see two solutions:

• Remove this line from FAKE (at least a fast temporary fix)
• Remove the "old" FSI output from FCS (I don't think it makes sense in FCS)

[forki]

I did the first one - fsprojects/FAKE@d1b9226

Anybody up for the second?

[sergey-tihon]

I recompiled FAKE using new FAKE and the message disappeared.

[7sharp9]

Is this still an issue?

[sergey-tihon]

Yes, FCS still prints this messages.

[fsgit]

@sergey-tihon Could you please add a repro for this that involves FCS alone (not FAKE)?

[sergey-tihon]

helloworld.fsx script

printfn "Hello world"
2+2

demo.fsx script

#r "FSharp.Compiler.Service.dll"

open System
open System.IO
open Microsoft.FSharp.Compiler.Interactive.Shell

let main () =
    let fsiConfig = FsiEvaluationSession.GetDefaultConfiguration()
    let commonOptions = [| "fsi.exe"; "--noninteractive" |]

    let sbOut = Text.StringBuilder()
    use outStream = new StringWriter(sbOut)
    use stdin = new StreamReader(Stream.Null)

    let session = FsiEvaluationSession.Create(fsiConfig, commonOptions, stdin, outStream, outStream)

    session.EvalScript @"d:\Downloads\fsharp.compiler.service.0.0.62.nupkg\lib\net45\helloworld.fsx"

    printfn "%s" (sbOut.ToString())

main()

Result of execution:

Hello world

F# Interactive for F# 3.1 (private)
Freely distributed under the Apache 2.0 Open Source License

For help type #help;;

> [Loading d:\Downloads\fsharp.compiler.service.0.0.62.nupkg\lib\net45\helloworld.fsx]

namespace FSI_0001


val it : unit = ()

[dsyme]

This is not strictly speaking a bug. The sbOut stream captures all the diagnostics from the FsiEvaluationSession, including the banner text. The printfn in the script goes to Console.Out (which is not automatically redirected).

I adjusted the script to also capture Console.Out and things seemed to work correctly:

    let origout = System.Console.Out
    try 
      System.Console.SetOut outStream

      let session = FsiEvaluationSession.Create(fsiConfig, commonOptions, stdin, outStream, outStream)

      session.EvalScript @"hello.fsx"
    finally 
      System.Console.SetOut origout

[dsyme]

Given this I think we can probably close this, though the behaviour is a bit strange.