[BUG]

[ewtoombs]

Version of Kakoune

archlinux 2024.05.18-2

Reproducer

Open a .tex file with this line in it:

$\pi(\hat v)$ is the probability per unit solid angle of the particle escaping with trajectory $\hat v$.

Outcome

This gets highlighted as if it were a formula:

$\pi(\hat v)$ is the probability per unit solid angle of the particle escaping with trajectory $\hat v$.
            ( from here...                                                           to here.  )

Expectations

This should get highlighted instead.

$\pi(\hat v)$ is the probability per unit solid angle of the particle escaping with trajectory $\hat v$.
(  here     )                                                                             and  ( here )

Additional information

It has something to do with the backslash.
If a formula does not start with a backslash, the syntax highlighting works fine.

[ewtoombs]

I've been trying to diagnose this madness by directly editing /usr/share/kak/rc/filetype/latex.kak and seeing what happens.
It makes no sense at all.

When I disable all highlighting except

add-highlighter shared/latex regions
add-highlighter shared/latex/content default-region group
add-highlighter shared/latex/content/ regex '(?<!\\)(?:\\\\)*\K\$(\\\$|[^$])+\$|(?<!\\)(?:\\\\)*\K\$\$(\\
»   \$|[^$])+\$\$|(?<!\\)(?:\\\\)*\K\\\[.*?\\\]|\\\(.*?\\\)' 0:meta

the math highlighting works (and all other highlighting is disabled).
Then, when I add just this line:

add-highlighter shared/latex/cs/ regex '(?:\\[a-zA-Z@]+)' 0:keyword

everything breaks!
There is no more highlighting at all.

What the hell is going on with this software?
I give up trying to solve this on my own.

[Screwtapello]

In the snippet you posted, shared/latex is a "regions" highlighter, so everything inside it must be a "region" or "default-region" highlighter.

shared/latex/content is created as a "default-region" highlighter, which is fine. The default region contains a "group" highlighter, and the regex is an anonymous highlighter within that group, so that's fine.

The extra line you add is trying to create an anonymous regex highlighter inside shared/latex/cs, but that highlighter isn't defined anywhere, so Kakoune probably throws an error that prevents the rest of the filetype plugin from running, including the bit that applies the highlighters when you open a LaTeX file.