Re: Inconsistent interline space in multitable

[Gavin Smith]

On Sun, Jul 07, 2019 at 09:28:53AM +0200, Akim Demaille wrote:
> Hi all,
> 
> Bison's documentation includes a table about the short options, long options, 
> and corresponding directives.  Some long options do not have a short option 
> and/or a directive.
> 
> The source looks like this:
> 
> > @multitable {@option{--force-define=@var{name}[=@var{value}]}} {@option{-F 
> > @var{name}[=@var{value}]}} {@code{%nondeterministic-parser}}
> > @headitem Long Option @tab Short Option @tab Bison Directive
> > 
> > @item @option{--color[=@var{when}]}
> > @tab
> > @tab
> > 
> > @item @option{--debug}
> > @tab @option{-t}
> > @tab @code{%debug}
> > 
> > @item @option{--define=@var{name}[=@var{value}]}
> > @tab @option{-D @var{name}[=@var{value}]}
> > @tab @code{%define @var{name} [@var{value}]}
> 
> As you can see, the space between the lines is inconsistent:
> 

>From what I can tell, the space between the rows is not actually really 
space between the rows at all: it is space within one of the cells (vertical
@parskip glue).  

This is evident when the inter-row space comes from a space within a 
non-row-final cell.  Look at this example input:

@multitable {Long Option} {Short Option} {Bison Directive}
@headitem Long Option @tab Short Option @tab Bison Directive

@item one
@tab qqq
@tab 
@item two
@tab qqq

@tab 
@item three
@tab qqq
@tab
@item four
@tab qqq
  
@item five
@tab qqq
@tab gggg

@end multitable

In row "one", no space follows the row.  In row "two", there is space after
the row even though there is no space following the row in the source: the
space comes from the empty line in the first cell in the row.

One simple solution is to omit the final @tab, as in row "four" in the 
example.

Another option is to mark empty content with "@w{}" but this is uglier.

> The result is comparable in Info:

That is fortunate.  The input above gives the same output in Info too.

> HTML is correct.

I'm guessing this is because vertical glue after a paragraph is ignored if
there is no paragraph that follows.