From a898ad3933b53735dd8f3d3fdceda6756ad7e5bf Mon Sep 17 00:00:00 2001
From: Andrew Stacey <loopspace@mathforge.org>
Date: Tue, 9 Jan 2024 21:41:20 +0000
Subject: [PATCH] More robust fix for foreach

This adds in the saving code for `\tikztostart` and `\tikz@tangent`,
plus provides a more robust and maintainable method of saving the
various macros and dimensions by creating a single (global) token list
that will restore them to their given values upon invocation.

Signed-off-by: Andrew Stacey <loopspace@mathforge.org>
---
 .../pgf/frontendlayer/tikz/tikz.code.tex      | 72 +++++++++++++------
 1 file changed, 50 insertions(+), 22 deletions(-)

diff --git a/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex b/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex
index 1415fdd3c..31202cddb 100644
--- a/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex
+++ b/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex
@@ -2580,31 +2580,64 @@
 
 \def\tikz@fchar oreach{\tikz@foreach}%
 
-\def\tikz@foreach{%
+\def\tikzforeach@smugglers@cove{}
+\let\tikztostart=\relax
+
+\def\tikzforeach@smuggle@macro#1{%
+  \pgfutil@ifx#1\relax{}{%
+    \expandafter
+    \pgfutil@g@addto@macro
+    \expandafter
+    \tikzforeach@smugglers@cove
+    \expandafter
+    {%
+      \expandafter\def\expandafter#1\expandafter{#1}%
+    }%
+  }%
+}
+
+\def\tikzforeach@smuggle@dimen#1{%
+  \pgfutil@ifx#1\relax{}{%
+    \expandafter
+    \pgfutil@g@addto@macro
+    \expandafter
+    \tikzforeach@smugglers@cove
+    \expandafter
+    {%
+      \expandafter#1\expandafter=\the#1\relax%
+    }%
+  }%
+}
+
+\def\tikzforeach@smugglers@loot{%
+  %
+  \tikzforeach@smuggle@macro\tikz@moveto@waiting%
+  \tikzforeach@smuggle@macro\tikztostart%
+  \tikzforeach@smuggle@macro\tikz@tangent%
+  %
+  \tikzforeach@smuggle@dimen\tikz@lastx%
+  \tikzforeach@smuggle@dimen\tikz@lasty%
+  \tikzforeach@smuggle@dimen\tikz@lastxsaved%
+  \tikzforeach@smuggle@dimen\tikz@lastysaved%
+  %
+}
+
+
+\def\tikz@patched@foreach{%
   \def\pgffor@beginhook{%
-    \global\let\tikz@moveto@waiting\tikz@foreach@moveto@waiting%
-    \tikz@lastx=\tikz@foreach@save@lastx%
-    \tikz@lasty=\tikz@foreach@save@lasty%
-    \tikz@lastxsaved=\tikz@foreach@save@lastxsaved%
-    \tikz@lastysaved=\tikz@foreach@save@lastysaved%
+    \tikzforeach@smugglers@cove%
+    \gdef\tikzforeach@smugglers@cove{}%
     \setbox\tikz@figbox=\box\tikz@tempbox%
     \setbox\tikz@figbox@bg=\box\tikz@tempbox@bg%
     \expandafter\tikz@scan@next@command\pgfutil@firstofone}%
   \def\pgffor@endhook{\pgfextra{%
-      \global\let\tikz@foreach@moveto@waiting\tikz@moveto@waiting%
-      \xdef\tikz@foreach@save@lastx{\the\tikz@lastx}%
-      \xdef\tikz@foreach@save@lasty{\the\tikz@lasty}%
-      \xdef\tikz@foreach@save@lastxsaved{\the\tikz@lastxsaved}%
-      \xdef\tikz@foreach@save@lastysaved{\the\tikz@lastysaved}%
+      \tikzforeach@smugglers@loot%
       \global\setbox\tikz@tempbox=\box\tikz@figbox%
       \global\setbox\tikz@tempbox@bg=\box\tikz@figbox@bg%
       \pgfutil@gobble}}%
   \def\pgffor@afterhook{%
-    \let\tikz@moveto@waiting\tikz@foreach@moveto@waiting%
-    \tikz@lastx=\tikz@foreach@save@lastx%
-    \tikz@lasty=\tikz@foreach@save@lasty%
-    \tikz@lastxsaved=\tikz@foreach@save@lastxsaved%
-    \tikz@lastysaved=\tikz@foreach@save@lastysaved%
+    \tikzforeach@smugglers@cove
+    \gdef\tikzforeach@smugglers@cove{}%
     \let\pgffor@beginhook\relax%
     \let\pgffor@endhook\relax%
     \let\pgffor@afterhook\relax%
@@ -2613,14 +2646,9 @@
     \tikz@scan@next@command}%
   \global\setbox\tikz@tempbox=\box\tikz@figbox%
   \global\setbox\tikz@tempbox@bg=\box\tikz@figbox@bg%
-  \xdef\tikz@foreach@save@lastx{\the\tikz@lastx}%
-  \xdef\tikz@foreach@save@lasty{\the\tikz@lasty}%
-  \xdef\tikz@foreach@save@lastxsaved{\the\tikz@lastxsaved}%
-  \xdef\tikz@foreach@save@lastysaved{\the\tikz@lastysaved}%
-  \global\let\tikz@foreach@moveto@waiting\tikz@moveto@waiting%
+  \tikzforeach@smugglers@loot%
   \foreach}%
 
-
 % Syntax for againpath:
 % \againpath \somepathname