[luatex] Bug in tex.linebreak ?

[Hans Hagen]

On 3/9/2016 8:48 PM, Frank Mittelbach wrote:
> I think I found a bug in tex.linebreak.
>
> Consider the following code
>
>
> function prelinebreak (head, groupnode)  --- for pre_linebreak_filter
>                                           --- for example
>    local n,t
>
>    n, t = tex.linebreak(node.copy_list(head), {looseness = -1})
>    print("looseness=" .. t.looseness)
>    n, t = tex.linebreak(node.copy_list(head), {looseness = 0})
>    print("looseness=" .. t.looseness)
>
>    return true
>
> end
>
> and pass it in head a long enough hlist so that looseness -1 actually
> works. The second line breaking with looseness=0 reports the previous
> looseness ... same happens if you have looseness=+2 or +1 or so
>
> it seems that tex.linebreak always reports the looseness of the previous
> linebreak action in case you pass it a "0"

it helps if you also set some more (either explicit or at the tex 
level), like:

   looseness=1,
   tolerance=4500,
   pretolerance=100,
   emergencystretch=655360


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