bug#40155: 27.0.90; `math-truc' called with `nil' during `calc-graph-fast' call

[Narendra Joshi]

Hi Mattias,

Thanks for the explanation. The patch fixes the original issue and
other calculations I tried didn't seem to be affected.

I found out that `calc` doesn't set the LineStyles (and maybe
PointStyles as well but I am not sure how to hand those over to
gnuplot command) properly for the gnuplot command. I think it should
do something similar to the patch I have attached.

Best,
Narendra

On Fri, Mar 27, 2020 at 6:37 PM Mattias Engdegård <mattiase@acm.org> wrote:
>
> Thanks for the report. Explanation:
>
> The graph code does
>
> (and (Math-num-integerp lstyle) (math-trunc lstyle))
>
> but Math-num-integerp returns true for nil, and math-trunc returns the 
> argument if it satisfies Math-integerp, which used to return true for nil as 
> well. Thus, the expression above 'works' (ie, returns nil) when lstyle is nil 
> as well.
>
> However, Math-integerp was changed in Emacs 27 to use native bignums, and no 
> longer returns true for nil, resulting in the error. Changing 
> Math-num-integerp to return false for nil would make the code work again, 
> this time in the way originally intended.
>
> Would you try this patch? (Please try various other operations as well, in 
> case the change had unintended consequences.)
>

0001-Fix-setting-linestyle-in-calc-graph-fns.patch
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