U+0085 not recognised as a newline character in CSharpCodeGenerator.cs (#1740)

[hamarb123]

U+0085 is not recognised as a newline character in CSharpCodeGenerator.cs, this fixes that.

This an issue is because it is recognised as a newline character in C# (see here), which cannot be in literal strings.

Specifically:

new_line_character
    : '<Carriage return character (U+000D)>'
    | '<Line feed character (U+000A)>'
    | '<Next line character (U+0085)>'
    | '<Line separator character (U+2028)>'
    | '<Paragraph separator character (U+2029)>'
    ;

and

regular_string_literal
    : '"' regular_string_literal_character* '"'
    ;

regular_string_literal_character
    : single_regular_string_literal_character
    | simple_escape_sequence
    | hexadecimal_escape_sequence
    | unicode_escape_sequence
    ;

single_regular_string_literal_character
    : '<Any character except " (U+0022), \\ (U+005C), and new_line_character>'
    ;

If the CSharpCodeGenerator class was used to make code with a string in it that has U+0085 in it, it would generate invalid C# code.

I have also added a test which ensures that all of the newline characters (other than \n and \r) are generated properly.

Fix for #1740

[dnfclas]

All CLA requirements met.

[hamarb123]

It seems like the test is failing on 2 platforms: Windows_NT netfx x86 Release, and Windows_NT x64.
I imagine the reasoning behind the netfx failure is because it must still have the old code, but can anyone tell me what the other one is, its error messages don't make sense to me.
Also, what should I do to fix the netfx one, should I just revert the tests for the netfx platform, or is there something else that I should do?

[hamarb123]

This change will be disabled for .NET Framework, and Microsoft can add it if they wish, see #1913

[hamarb123]

As all of the checks have now passed, this is now ready for review.
Edit: also note, the numbers in 'Merge pull request #number' aren't accurate AFAIK, I'm pretty sure the 2nd one wasn't merging PR #2, it was just the second one merged.

[stephentoub]

LGTM. Thanks.

[cston]

Thanks @hamarb123!