Hi TikZ masters, I tried

Hi Ti_k_Z masters, I tried

\documentclass[border=10pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
    \draw[trig format=rad,red]  (0:1) arc[start angle=0, end angle=pi, radius=1];
\draw[blue] (0:1) arc(0:180:1);
\end{tikzpicture}
\end{document}

Romano Giannetti I have the feeling that there're many more cases where /pgf/trig format=rad will break. Note /pgf/trig format is (still) documented as experimental, https://tikz.dev/math-parsing#pgf/trig:format.

At the time of this writing, this feature is “experimental”. Please handle it with care: there may be path instructions or libraries in pgf which rely on trig format=deg. The intended usage of trig format=rad is for local scopes – and as option for data visualization.

Personally I would suggest to do rad-to-degree conversion by deg(<rad>) pgfmath function or <rad> r postfix operator.

\documentclass[border=10pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
  \draw[red]
    (0:1) arc[start angle=0 r, end angle=pi r, radius=1];
  \draw[red!50, xshift=-.1cm]
    (0:1) arc[start angle=deg(0), end angle=deg(pi), radius=1];

  \draw[blue, xshift=.1cm] (0:1) arc (0:180:1);
\end{tikzpicture}
\end{document}

In reply to @josephwright:matrix.org
hmenke: Following our discussion at TUG2023 - do you have any examples where making kernel commands \protected would help pgf? We have a potential plan but I need to see if it helps at all

In reply to @muzzi:matrix.org
Sorry for bothering, what does the "kernel commands" mean?

Romano Giannetti (Aha, current comment is almost identical to what Qrrbrbirlbel's TeX-SX answer says. My apologies that I didn't read through the answer...)

I have the feeling that there're many more cases where /pgf/trig format=rad will break. Note /pgf/trig format is (still) documented as experimental, https://tikz.dev/math-parsing#pgf/trig:format.

At the time of this writing, this feature is “experimental”. Please handle it with care: there may be path instructions or libraries in pgf which rely on trig format=deg. The intended usage of trig format=rad is for local scopes – and as option for data visualization.

Personally I would suggest to do rad-to-degree conversion by deg(<rad>) pgfmath function or <rad> r postfix operator.

\documentclass[border=10pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
  \draw[red]
    (0:1) arc[start angle=0 r, end angle=pi r, radius=1];
  \draw[red!50, xshift=-.1cm]
    (0:1) arc[start angle=deg(0), end angle=deg(pi), radius=1];

  \draw[blue, xshift=.1cm] (0:1) arc (0:180:1);
\end{tikzpicture}
\end{document}

In reply to @r_mano:matrix.org
from here https://tex.stackexchange.com/questions/685949/why-arc-with-angles-given-by-trig-format-rad-gives-wrong-result and it fails with also the new syntax. There is a proposed patch by qrr there... is that know or somebody should open an issue?

In reply to @r_mano:matrix.org
from here https://tex.stackexchange.com/questions/685949/why-arc-with-angles-given-by-trig-format-rad-gives-wrong-result and it fails with also the new syntax. There is a proposed patch by qrr there... is that know or somebody should open an issue?

In reply to @hmenke:matrix.org
josephwright: Also with increasing usage of Lua, users tend to try \directlua{tex.sprint("\textbf{foo}"} which then blows up in their face.

In reply to @hmenke:matrix.org
josephwright: In pgfmath you can use quotes to measure text, such as\pgfmathparse{width("Some Lovely Text")}. Internally we are already using \protected@edef but it doesn't roundtrip really cleanly. At some point someone used pgfmath arrays to select a certain text from a list and measure stuff about it, but somewhere in between there was an \edef (I don't remember whether it was in user code or pgf code).

Qrrbrbirlbel: Hi I saw two of your PRs (#1179 and #1182) were closed last week due to deletion of the head repository (your pgf fork https://github.com/Qrrbrbirlbel/pgf-tikz, now invalid).

It seems then you re-created a pgf fork (https://github.com/Qrrbrbirlbel/tikz-sloped) for PR #1287 (maybe because the default branch "master" in your fork is used as the head branch in #1287), thus I'm guessing you might still want to contribute the closed two PRs in the future?

Qrrbrbirlbel: Hi I saw two of your PRs (#1179 and #1182) were closed last week due to deletion of the head repository (your pgf fork https://github.com/Qrrbrbirlbel/pgf-tikz, now invalid).

It seems then you re-created a pgf fork (https://github.com/Qrrbrbirlbel/tikz-sloped) for PR #1287 (maybe because the default branch "master" in your fork is used as the head branch in #1287), thus I'm guessing you might still want to contribute the closed two PRs in the future?