I just run in a tex capacity problem with \prop_map_inline when a
property list is not declared and the c-type-Argument is used to
fill the list:

\documentclass{article}
\usepackage{expl3}
\begin{document}
\ExplSyntaxOn
%\prop_new:c{test_prop}                %solve the recursion
%\prop_gput:Nno\test_prop{datum}{blub} %give error
\prop_gput:cno      {test_prop}{datum}{bkabka}
\prop_show:c{test_prop} 
\prop_map_inline:cn {test_prop}
  {#1,#2}  

\ExplSyntaxOff 
\end{document}


The property list \test_prop contains the pairs (without outer
braces):
>  {datum}  =>  {bkabka}.
<recently read> }

l.28 \prop_show:N\test_prop

?
! TeX capacity exceeded, sorry [input stack size=5000].
\test_prop ->\test_prop
                        \__prop_pair:wn datum\s__prop {bkabka}

Is this a bug? Or simply something one must remember when using
c-type arguments? 



-- 
Ulrike Fischer 
http://www.troubleshooting-tex.de/