[luatex] \vsplit issue

[Joseph Wright]

On 21/05/2016 12:46, luigi scarso wrote:
> On Sat, May 21, 2016 at 12:40 AM, luigi scarso <luigi.scarso at gmail.com>
> wrote:
> 
>>
>>
>> On Sat, May 21, 2016 at 12:19 AM, luigi scarso <luigi.scarso at gmail.com>
>> wrote:
>>
>>>
>>>
>>> On Fri, May 20, 2016 at 11:58 PM, luigi scarso <luigi.scarso at gmail.com>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Fri, May 20, 2016 at 10:58 PM, Joseph Wright <
>>>> joseph.wright at morningstar2.co.uk> wrote:
>>>>
>>>>> Hello all,
>>>>>
>>>>> The example
>>>>>
>>>>>     \setbox0=\vbox{a\par b\par c\par d}
>>>>>     \setbox2=\vsplit0 to 2cm %
>>>>>     %\showboxbreadth\maxdimen
>>>>>     %\showboxdepth\maxdimen
>>>>>     %\showbox2 %
>>>>>     \bye
>>>>>
>>>>> gives an underful vbox with pdfTeX, leading to a warning and box trace
>>>>> in the log. The same isn't the case for LuaTeX (v0.95 from TL'16), which
>>>>> comes from the fact the box is no longer the same size:
>>>>>
>>>>>     > \box2=
>>>>>     \vbox(40.30554+0.0)x469.75499, direction TLT
>>>>>
>>>>> from LuaTeX, wherease pdfTeX gives
>>>>>
>>>>>     > \box2=
>>>>>     \vbox(56.9055+0.0)x469.75499, glue set 5.53333
>>>>>
>>>>> An error?
>>>>>
>>>>> Joseph
>>>>>
>>>>
>>>> thank you for the report, we are seeing it.
>>>>
>>>> --
>>>> luigi
>>>>
>>> It's a bug:
>>> we have a patch, but we also want to implement upto
>>>
>>> \vsplit to 2cm
>>> \vsplit upto 2cm
>>>
>>> so this keyword saves a \setbox2\vbox{\unvbox2}
>>>
>>> We will commit it to experimental (which is already 0.96.0,
>>>
>>>
>>  ------------------------------------------------------------------------
>> r6017 | luigi | 2016-05-21 00:40:03 +0200 (Sat, 21 May 2016) | 1 line
>> Changed paths:
>>    M /branches/experimental/source/texk/web2c/luatexdir/tex/packaging.w
>>
>> fix for vsplit and new upto (HH)
>> ------------------------------------------------------------------------
>>
>>
>> --
>> luigi
>>
> 
> 
> ------------------------------------------------------------------------
> r6018 | luigi | 2016-05-21 13:45:32 +0200 (Sat, 21 May 2016) | 1 line
> Changed paths:
>    M /branches/experimental/manual/luatex-callbacks.tex
>    M /branches/experimental/manual/luatex-enhancements.tex
>    M /branches/experimental/manual/luatex.pdf
> 
> updated manual (HH)
> ------------------------------------------------------------------------

Thanks for that: use case for new keyword quite clear :-)

Joseph