On Mon, 2022-04-25 at 22:09 +0200, Henri Menke wrote:
> Dear devs,
>
> When using delimiter with \left...\right the italic correction
> between
> the preceding letter and the delimiter is dropped. I've tried this
> with
> a few fonts and all show the problem. For Libertinus Math the glyphs
> even overlap.
>
> MWE for mtxrun --script plain (TeX Live 2022)
>
>    %\input luaotfload.sty
>    \font\mathfont="file:LibertinusMath-
> Regular.otf:mode=base;script=math" at 10pt
>    \textfont0=\mathfont
>    \textfont2=\mathfont
>   
>    \Umathcodenum`f="1D453
>    \protected\def\langle{\Udelimiter"4"0"27E8\relax}
>    \protected\def\rangle{\Udelimiter"5"0"27E9\relax}
>   
>    $f\rangle$
>   
>    \nulldelimiterspace=0pt
>    $\left.f\right\rangle$
>   
>    \bye

Ulrike pointed out \mathitalicsmode=1 on TeX Stack Exchange, but there
is still an issue with sub_mlists:

   %\input luaotfload.sty
   \font\mathfont="file:LibertinusMath-Regular.otf:mode=base;script=math" at 10pt
   \textfont0=\mathfont
   \textfont2=\mathfont

   \Umathcodenum`f="1D453
   \protected\def\langle{\Udelimiter"4"0"27E8\relax}
   \protected\def\rangle{\Udelimiter"5"0"27E9\relax}

   \mathitalicsmode=1

   $f\rangle$

   \nulldelimiterspace=0pt
   $\left.f\right\rangle$

   ${-f}\rangle$

   $\left.{-f}\right\rangle$

   \bye