Unexpected identifier in lambda expression when using pre processor directives

[theimowski]

Issue created from fantomas-online

Code

let a = (fun _ -> function
    | A ->
        ()
#if DEBUG
        f()
#endif
    | B ->
        ()
)

Error

Fantomas.FormatConfig+FormatException: Parsing failed with errors: [|tmp.fsx (6,9)-(6,10) parse error Unexpected identifier in lambda expression. Expected incomplete structured construct at or before this point or other token.|]
And options: { SourceFiles = [|"tmp.fsx"|]
  ConditionalCompilationDefines = ["DEBUG"]
  ErrorSeverityOptions = { WarnLevel = 3
                           GlobalWarnAsError = false
                           WarnOff = []
                           WarnOn = []
                           WarnAsError = []
                           WarnAsWarn = [] }
  IsInteractive = false
  LightSyntax = None
  CompilingFsLib = false
  IsExe = false }
   at Fantomas.CodeFormatterImpl.parse@76-2.Invoke(FSharpParseFileResults _arg2) in /home/runner/work/fantomas-tools/fantomas-tools/.deps/fantomas/src/Fantomas/CodeFormatterImpl.fs:line 82
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvokeNoHijackCheck[a,b](AsyncActivation`1 ctxt, FSharpFunc`2 userCode, b result1) in D:\workspace\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 404
   at <StartupCode$FSharp-Compiler-Service>.$Service.ParseFile@457-3.Invoke(AsyncActivation`1 ctxt) in D:\workspace\_work\1\s\src\fsharp\service\service.fs:line 457
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in D:\workspace\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 104

Problem description

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Extra information

• 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 at 02/26/2021 10:32:56 - 6464684

    { config with
                IndentSize = 2 }

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

[nojaf]

Thank you for reporting!