TikZ does not allow long macros

[ilyaza]

Brief outline of the bug

If a macro inside a TikZ command produces only “simple” operations, then (without the enclosed patch) the length of the macro is severely bounded. (Currently, there is a code to work around this, but it only triggered if a “complicated” primitive is issued.)

--- tikz.code.tex-orig	2021-08-23 19:38:15.955899500 -0700
+++ tikz.code.tex	2021-11-09 16:05:40.344118700 -0800
@@ -2173,6 +2173,7 @@
       \fi%
     \fi%
   \fi%
+  \ifx\pgfutil@next\tikz@handle@more\else\tikz@expandcount=100\relax\fi%
   \pgfutil@next%
 }%

Minimal working example (MWE)

\documentclass{article}
\usepackage{tikz}
\begin{document}

% Part of output of: perl -wle "sub B($){(my $p=reverse shift) =~ tr/RDLU/DLUR/; $p} sub D($$);sub D($$) {my ($p,$c)=(shift,shift); $c>0 ? ($p=D($p, $c-1), $p.B $p) : $p} print join q(\\), q(), split //, D q(R), $_ for 0..7"
\def\DRx{\R\D\L\D\L\U\L\D\L\U\R\U\L\U\L\D\L\U\R\U\R\D\R\U\L
         \U\R\U\L\U\L\D\L\U\R\U\R\D\R\U\R\D\L\D\R\D\R\U\L\U
         \R\U\R\D\R\U\L\U\R\U\L\U\L\D\L\U\R\U\R\D\R\U\R\D\L
         \D\R\D\R\U\R\D\L\D\L\U\L\D\R\D\L\D\R\D\R\U\L\U\R\U
         \R\D\R\U\R\D\L\D\R\D\R\U\L\U\R\U\R\D\R\U\L\U\R\U\L}

\tikz{ \def\R{ -- ++(1,0) }%    Poor man's l-system
       \def\U{ -- ++(0,1) }
       \def\L{ -- ++(-1,0) }
       \def\D{ -- ++(0,-1) }
       \draw[rounded corners=2mm] (0,0) \DRx ;}

\end{document}

[muzimuzhi]

I think this is a duplicate of #969, which is already fixed in #970 and the fix is available since v3.1.9.

Edit: Also, tikz's turtle library maybe an alternative in drawing your example.

[hmenke]

Not reproducible on either up-to-date TL2021 or latest master.

[ilyaza]

Just for completeness: I have been testing this with the stock TeXLive2021. Thanks for fixing this in the current version!