Wrong error line separators in console build

[auduchinok]

It happens consistently across different OS and terminal/console clients with either corrupted symbols or no new line in build outputs.

@vasily-kirichenko found this code that looks related:
https://github.com/Microsoft/visualfsharp/blob/51dac00d62a7f6f6fb714f4cef6cb3912abf58df/src/fsharp/ErrorLogger.fs#L611-L614

[auduchinok]

Related Rider issue:

[vasily-kirichenko]

The code that looks responsible for this is

// Code below is for --flaterrors flag that is only used by the IDE

let stringThatIsAProxyForANewlineInFlatErrors = new System.String [|char 29 |]

let NewlineifyErrorString (message:string) = message.Replace(stringThatIsAProxyForANewlineInFlatErrors, Environment.NewLine)

[dsyme]

@auduchinok This is by design I believe - the Fsc task sets --flaterrors and has done for at least a couple of years, I think more https://github.com/Microsoft/visualfsharp/blame/master/src/fsharp/FSharp.Build/Fsc.fs#L220

I think you're meant to de-flatten them if you want multi-line in the IDE, search around the VF# code

[dsyme]

I'll close this since it's by deign

[auduchinok]

@dsyme What about console builds? I don't think it's OK to have wrong line separators when you build without an IDE.

[dsyme]

@auduchinok I know, I used to think that and it used to work like that in 2006 but the decision was otherwise. I think it's because too many build-output processing tools want single-line error output. I don't think we should change it now unless it's changed inadvertently somewhere along the way (I don't think it has, but I may be wrong)