Language spec must describe semantics of leading newline in multiline string

[DartBot]

This issue was originally filed by olov.l...@gmail.com

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A multiline string literal that doesn't include a leading newline (i.e. """hello...) is parsed correctly but when the literal includes at least one leading newline, the first of those is ignored. dartc doesn't have the bug.

main() {
  var str = """
hello
""";
  Expect.equals("\n", str[0], "str should include a leading newline");
}

[DartBot]

This comment was originally written by @mhausner

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This is actually a feature, not a bug. The language spec is lacking a description of this.

Making this a spec bug.

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Changed the title to: "Language spec must describe semantics of leading newline in multiline string".

[DartBot]

This comment was originally written by @mhausner

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Added Area-Language label.

[DartBot]

This comment was originally written by olov.l...@gmail.com

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If this is a feature then there's still an implementation bug to fix (in dartc). Should I open another issue for that or will you adjust the title?

I'd like to discuss this feature more, starting a thread about that on misc.

[DartBot]

This comment was originally written by olov.lass...@gmail.com

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The discussion in misc suggests that this is actually a bug, not a feature. I suggest that the original title of the bugreport is restored and that it's assigned to VM.

I cannot retrieve the original title but it was something along the lines of "Dart VM ignores leading newline in multiline string".

<https://groups.google.com/a/dartlang.org/group/misc/browse_thread/thread/349f1cbb1bbb5ed4#>

[iposva-google]

The current behaviour in the VM is as it was initially intended. Since this is not clear in the spec I am keeping this as a language/spec bug. The final resolution of this bug is either a clearer specification or it might be a change to the spec at which point we will update the VM implementation.

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Set owner to @gbracha.
Added Accepted label.

[DartBot]

This comment was originally written by olov.las...@gmail.com

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I filed issue #398: "dartc should ignore leading newline in multi-line strings, like VM"

[scheglov]

Yes, but what is NEWLINE?
According to spec right now:

NEWLINE:
\n' | \r'
;

  So, NEWLINE is '\n' or '\r'

  However 03_3_Strings_A03_t01.dart and all co19/src/LangGuideTest/03_Values tests use Windows style newline "\r\n".
  So, these tests are invalid, or spec should state that '\r\n' is also valid NEWLINE.

  JFYI, DartC right now skips leading '\n' (and only it).
  I can easily add '\r', but I can not add '\r\n' because it is not in spec.

[DartBot]

This comment was originally written by olov.l...@gmail.com

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dartc and the VM being consistent (accepting '\r\n' as newline) would be a good thing. The spec defining it clearly, likewise.

Right now try.dartlang fails on the example <http://try.dartlang.org/s/BYUf> which is a bit confusing to those trying out the language.

[anders-sandholm]

Added apr30-triage label.

[anders-sandholm]

Removed apr30-triage label.

[anders-sandholm]

Added triage1 label.

[anders-sandholm]

Added this to the M1 milestone.
Removed triage1 label.

[gbracha]

Issue #398 has been merged into this issue.

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cc @peter-ahe-google.

[gbracha]

Fixed in 0.09 draft.

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Added Done label.