http://d.puremagic.com/issues/show_bug.cgi?id=8730

           Summary: writeln stops on a nul character, even if passed a D
                    string
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: minor
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: destructionator@gmail.com


--- Comment #0 from Adam D. Ruppe <destructionator@gmail.com> 2012-09-26 13:12:00 PDT ---
import std.stdio;

void main() {
        writeln("test\0gone");
}


only prints "test". writefln("%s") prints the whole thing.

$ ./test | xxd
0000000: 7465 7374 0a

as you can see the data is indeed not being printed; it isn't just invisible on my screen.

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-04 17:11:33 PDT ---
I'm just guessing, but:

void writeln(T...)(T args)
{
    static if (T.length == 0)
    {
        enforce(fputc('\n', .stdout.p.handle) == '\n');
    }
    else static if (T.length == 1 &&
                    is(typeof(args[0]) : const(char)[]) &&
                    !is(typeof(args[0]) == enum) && !is(typeof(args[0]) ==
typeof(null)) &&
                    !isAggregateType!(typeof(args[0])))
    {
        // Specialization for strings - a very frequent case
        enforce(fprintf(.stdout.p.handle, "%.*s\n",
                        cast(int) args[0].length, args[0].ptr) >= 0);
    }
    else
    {
        // Most general instance
        stdout.write(args, '\n');
    }
}

The specialization is probably to blame. I think 'args[0].length' probably sets the max limit rather than min, but I don't know enough about fprintf internals. :)

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--- Comment #2 from Adam D. Ruppe <destructionator@gmail.com> 2012-10-09 19:24:49 PDT ---
(In reply to comment #1)
> The specialization is probably to blame. I think 'args[0].length' probably sets the max limit rather than min, but I don't know enough about fprintf internals. :)


Yeah, you're right. The man page for printf says "the maximum number of
       characters to be printed from a string for s and S conversions."


I'm not sure what is best here. I really think it should work, but the specialization has got to be there for a reason too.

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--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-09 19:38:15 PDT ---
(In reply to comment #2)
> (In reply to comment #1)
> > The specialization is probably to blame. I think 'args[0].length' probably sets the max limit rather than min, but I don't know enough about fprintf internals. :)
> 
> 
> Yeah, you're right. The man page for printf says "the maximum number of
>        characters to be printed from a string for s and S conversions."
> 
> 
> I'm not sure what is best here. I really think it should work, but the specialization has got to be there for a reason too.

It could me off guard just recently. E.g. git uses two strings separated by nul in it's object format, and when I've tried to print out the contents as a char[] using writeln it would only print out a small portion of it, even though printing it as a byte[] would print much more.

Anyway this *is* a bug. We can't have it both ways:
writeln("bla\0bla");  // bla
writefln("%s", "bla\0bla");  // bla[NUL]bla

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Brad Roberts <braddr@puremagic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |braddr@puremagic.com


--- Comment #4 from Brad Roberts <braddr@puremagic.com> 2012-10-09 20:33:42 PDT ---
Shouldn't this be trivial to fix:

Replace:
fprintf(.stdout.p.handle, "%.*s\n",
                        cast(int) args[0].length, args[0].ptr)

with:
fwrite(args[0].ptr, 1, args[0].length, .stdout.p.handle)

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--- Comment #5 from Brad Roberts <braddr@puremagic.com> 2012-10-09 20:36:53 PDT ---
oops, followed by the same code as in the length == 0 code to get the \n.  At which point it's questionable that specialization is all that special.

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