reading a file produces odd (corrupt?) type statements

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3 files attached (possibly 2 - mytext_repro_empty.txt is an empty file which something doesn't seem to like). Code below, modify XXX to pick files.

val source = scala.io.Source.fromFile(raw"C:\testfiles\myText_XXXX.txt")
val f = source.toSeq

using file mytext_repro_empty.txt I get

f: Seq[Char] = Stream()

which seems right. Using mytext_repro4.txt I get

f: Seq[Char] = Stream(-, ?)

which is well formed, I suppose, but don't know what the dash and question mark indicate. Using mytext_repro5.txt I get

, ?)eq[Char] = Stream(

which is evidently broken.

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Imported From: https://issues.scala-lang.org/browse/SI-9829?orig=1
Reporter: ImNotTellingYouThat (intyt)
Affected Versions: 2.11.8
Attachments:

• mytext_repro4.txt (created on Jun 25, 2016 10:43:51 AM UTC, 118 bytes)
• mytext_repro5.txt (created on Jun 25, 2016 10:43:51 AM UTC, 120 bytes)

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ImNotTellingYouThat (intyt) said:
Indeed, mytext_repro_empty.txt didn't come through. Create as needed.

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ImNotTellingYouThat (intyt) said:
Just realised when reporting other bug that the question mark is because it's a stream. Sorry. Am a scala newbie.

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Gábor Bakos (aborg) said:
I do not think that is corrupt. One might say that carriage return character should not allow overwriting the content, but I guess that is how consoles work. The first two characters of the [^mytext_repro5.txt] file are a carriage return and a new line character. The scala streams are eager in their first element, but lazy in their second, so only the first character - carriage return - is read. That character moves the cursor to the beginning of the line (f: Seq[Char] = Stream() and from that the printing continues, overwriting the first four characters (f: S) with , ?), resulting in the output you described: , ?)eq[Char] = Stream(.

What is your expected output for such input? (In the toString() method of the Streams - as you also realized -, the first value is the eagerly consumed value, the ? represents the not yet read parts.)

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@som-snytt said:
Both these issues have previously stumped the chumps (experts): whether ? is real output or unprintable char in terminal; and CR messing with the output. There's a PR for pretty printing. The default printer could do more, like turn control chars into colorized escapes. scala/scala#5222

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ImNotTellingYouThat (intyt) said:
@gabor, @MarkI, thanks both. Quite predictable behavour if you know what's happening, baffling if not. Ok, I don't know whether to leave it open as a UI issue to be addressed per Marki's comments about stumping smarter people, or to close it as a nonbug, so please feel free to do either as you think best.
cheers
jan