Valid input => Formatted content is not valid F# code

[SteveGilham]

Issue created from fantomas-online

Code

let defaultTestOptions fwk common (o: DotNet.TestOptions) =
    { o.WithCommon(
          (fun o2 ->
              { o2 with
                    Verbosity = Some DotNet.Verbosity.Normal })
          >> common
      ) with
          NoBuild = true
          Framework = fwk // Some "netcoreapp3.0"
          Configuration = DotNet.BuildConfiguration.Debug }

Result

let defaultTestOptions fwk common (o: DotNet.TestOptions) =
    { o.WithCommon(
        (fun o2 -> { o2 with Verbosity = Some DotNet.Verbosity.Normal })
        >> common
    ) with
        NoBuild = true
        Framework = fwk // Some "netcoreapp3.0"
        Configuration = DotNet.BuildConfiguration.Debug }

Problem description

The above is a minimal part of https://github.com/SteveGilham/Gendarme/blob/f5f2cff920e02da819ded93708156b922f598fef/Build/targets.fsx a working Fake build script previously processed by Fantomas v4.5.9; at v4.6.5 it throws

The following exception occurs while formatting stdin: Fantomas.FormatConfig+FormatException: Formatted content is not valid F# code
   at Fantomas.Extras.FakeHelpers.formatContentInternalAsync@86-5.Invoke(Boolean _arg2) in C:\Users\nojaf\Projects\fantomas\src\Fantomas.Extras\FakeHelpers.fs:line 87
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvokeNoHijackCheck[a,b](AsyncActivation`1 ctxt, b result1, FSharpFunc`2 userCode) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 465
   at [email protected](AsyncActivation`1 ctxt) in C:\Users\nojaf\Projects\fantomas\src\Fantomas\CodeFormatterImpl.fs:line 370
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 105
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.FSharp.Control.AsyncResult`1.Commit() in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 392
   at Microsoft.FSharp.Control.AsyncPrimitives.QueueAsyncAndWaitForResultSynchronously[a](CancellationToken token, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 1044
   at Microsoft.FSharp.Control.AsyncPrimitives.RunSynchronously[T](CancellationToken cancellationToken, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 1070
   at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T](FSharpAsync`1 computation, FSharpOption`1 timeout, FSharpOption`1 cancellationToken) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 1365
   at Program.processSourceString(Boolean isFsiFile, String s, FSharpChoice`2 tw, FormatConfig config) in C:\Users\nojaf\Projects\fantomas\src\Fantomas.CoreGlobalTool\Program.fs:line 115
   at Program.stringToFile@343(Boolean force, Boolean profile, String s, String outFile, FormatConfig config) in C:\Users\nojaf\Projects\fantomas\src\Fantomas.CoreGlobalTool\Program.fs:line 355
Formatted content is not valid F# code

The online process seems to have lost track of either or both indentation and bracket nesting; the released tool is opaque as to what it choked on.

Extra information

• There is no formatted output
• The formatted result breaks by code.
• The formatted result gives compiler warnings.
• I or my company would be willing to help fix this.

Options

Fantomas master branch at 1/1/1990

Default Fantomas configuration

_{Did you know that you can ignore files when formatting from fantomas-tool or the FAKE targets by using a .fantomasignore file?}

[SteveGilham]

While binary chopping the file with (* *) comments, at the stage where the (* was on line 386 and the *) appended to the last line, there was another interesting error raised --

The following exception occurs while formatting stdin: Fantomas.FormatConfig+FormatException: Parsing failed with errors: [|tmp.fsx (386,1)-(386,3) parse error End of file in string embedded in comment begun at or before here|]
And options: { SourceFiles = [|"tmp.fsx"|]
  ConditionalCompilationDefines = []
  ErrorSeverityOptions = { WarnLevel = 3
                           GlobalWarnAsError = false
                           WarnOff = []
                           WarnOn = []
                           WarnAsError = []
                           WarnAsWarn = [] }
  LangVersionText = "preview"
  IsInteractive = false
  LightSyntax = None
  CompilingFsLib = false
  IsExe = true }
   at [email protected](FSharpParseFileResults _arg2) in C:\Users\nojaf\Projects\fantomas\src\Fantomas\CodeFormatterImpl.fs:line 78
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvokeNoHijackCheck[a,b](AsyncActivation`1 ctxt, b result1, FSharpFunc`2 userCode) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 465
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 105
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.FSharp.Control.AsyncResult`1.Commit() in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 392
   at Microsoft.FSharp.Control.AsyncPrimitives.QueueAsyncAndWaitForResultSynchronously[a](CancellationToken token, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 1044
   at Microsoft.FSharp.Control.AsyncPrimitives.RunSynchronously[T](CancellationToken cancellationToken, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 1070
   at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T](FSharpAsync`1 computation, FSharpOption`1 timeout, FSharpOption`1 cancellationToken) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 1365
   at Program.processSourceString(Boolean isFsiFile, String s, FSharpChoice`2 tw, FormatConfig config) in C:\Users\nojaf\Projects\fantomas\src\Fantomas.CoreGlobalTool\Program.fs:line 115
   at Program.stringToFile@343(Boolean force, Boolean profile, String s, String outFile, FormatConfig config) in C:\Users\nojaf\Projects\fantomas\src\Fantomas.CoreGlobalTool\Program.fs:line 355
Parsing failed with errors: [|tmp.fsx (386,1)-(386,3) parse error End of file in string embedded in comment begun at or before here|]
And options: { SourceFiles = [|"tmp.fsx"|]
  ConditionalCompilationDefines = []
  ErrorSeverityOptions = { WarnLevel = 3
                           GlobalWarnAsError = false
                           WarnOff = []
                           WarnOn = []
                           WarnAsError = []
                           WarnAsWarn = [] }
  LangVersionText = "preview"
  IsInteractive = false
  LightSyntax = None
  CompilingFsLib = false
  IsExe = true }

[nojaf]

Hello Steve, thank you for reporting this issue.

I think the copyInfo expression should be wrapped with an atCurrentColumnIndent at

fantomas/src/Fantomas/CodePrinter.fs

Line 2970 in ef132c1

+> genExpr astContext e

This will ensure that all lines of the expression stay on the correct column.

Are you interested in submitting a PR for this?