Exception when code for no defines is empty

[jindraivanek]

Issue created from fantomas-ui

Code

#if SOMETHING
let foo = 42
#endif

Error

Exception: Fantomas is trying to format the input multiple times due to the detect of multiple defines.
There is a problem with merging all the code back togheter. Please raise an issue at https://github.com/fsprojects/fantomas/issues. Stack Trace:    at Microsoft.FSharp.Core.PrintfModule.PrintFormatToStringThenFail@1637.Invoke(String message) in E:\A\_work\130\s\src\fsharp\FSharp.Core\printf.fs:line 1637
   at Fantomas.String.merge(String a, String b) in /build/.deps/fantomas/src/Fantomas/Utils.fs:line 59
   at Fantomas.CodeFormatterImpl.merged@445.Invoke(String a, String b) in /build/.deps/fantomas/src/Fantomas/CodeFormatterImpl.fs:line 445
   at Microsoft.FSharp.Collections.ListModule.Fold[T,TState](FSharpFunc`2 folder, TState state, FSharpList`1 list) in E:\A\_work\130\s\src\fsharp\FSharp.Core\list.fs:line 221
   at Microsoft.FSharp.Collections.ListModule.Reduce[T](FSharpFunc`2 reduction, FSharpList`1 list) in E:\A\_work\130\s\src\fsharp\FSharp.Core\list.fs:line 233
   at Fantomas.CodeFormatterImpl.format@431-1.Invoke(Tuple`2[] _arg1) in /build/.deps/fantomas/src/Fantomas/CodeFormatterImpl.fs:line 445
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvokeNoHijackCheck[a,b](AsyncActivation`1 ctxt, FSharpFunc`2 userCode, b result1) in E:\A\_work\130\s\src\fsharp\FSharp.Core\async.fs:line 416
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in E:\A\_work\130\s\src\fsharp\FSharp.Core\async.fs:line 109
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.FSharp.Control.AsyncResult`1.Commit() in E:\A\_work\130\s\src\fsharp\FSharp.Core\async.fs:line 349
   at Microsoft.FSharp.Control.AsyncPrimitives.RunSynchronouslyInCurrentThread[a](CancellationToken cancellationToken, FSharpAsync`1 computation) in E:\A\_work\130\s\src\fsharp\FSharp.Core\async.fs:line 870
   at Microsoft.FSharp.Control.AsyncPrimitives.RunSynchronously[T](CancellationToken cancellationToken, FSharpAsync`1 computation, FSharpOption`1 timeout) in E:\A\_work\130\s\src\fsharp\FSharp.Core\async.fs:line 890
   at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T](FSharpAsync`1 computation, FSharpOption`1 timeout, FSharpOption`1 cancellationToken) in E:\A\_work\130\s\src\fsharp\FSharp.Core\async.fs:line 1153
   at Server.Result.attempt[a](FSharpFunc`2 f) in /build/src/Server/Server.fs:line 23

Options

Fantomas Next - 3.0.0-9/15/2019

Name	Value
IndentSpaceNum	4
PageWidth	120
PreserveEndOfLine	false
SemicolonAtEndOfLine	false
SpaceBeforeArgument	true
SpaceBeforeColon	false
SpaceAfterComma	true
SpaceAfterSemicolon	true
IndentOnTryWith	false
ReorderOpenDeclaration	false
SpaceAroundDelimiter	true
KeepNewlineAfter	false
StrictMode	false

[nojaf]

@jindraivanek 253164d fixed the original bug. Do you think your changes are still needed for this?

[jindraivanek]

@nojaf Not needed anymore, I reverted it c198b3a. Thanks!