hotfix for #1641

base/changes.txt

@@ -10,6 +10,15 @@ not part of the distribution.
 All changes above are only part of the development branch for the next release.
 ================================================================================
 
+#########################
+# 2024-11-01 PL2 Release
+#########################
+
+2025-01-26  Frank Mittelbach  <[email protected]>
+
+	* ltlists.dtx:
+	Only migrate \cs{@doendpe} out of simple and semi-simple groups (gh/1641)
+
 #########################
 # 2024-11-01 PL1 Release
 #########################

base/ltlists.dtx

@@ -31,7 +31,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltlists.dtx}
-             [2024/06/23 v1.0u LaTeX Kernel (List Environments)]
+             [2025/01/26 v1.0v LaTeX Kernel (List Environments)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltlists.dtx}
@@ -851,11 +851,26 @@
 \def\@endpetrue {%
   \global\let\if@endpe\iftrue
 %    \end{macrocode}
-%    If we are inside a group then propagate to the outside:   
+%    If we are inside a simple or a semi-simple group then propagate
+%    to the outside, for all other group types do nothing. Normally, we
+%    would start out in the group opened by \cs{begin} (type 14). When we
+%    migrate out of that we are either on top-level (type 0) or in
+%    another semi-simple group (type 14) or
+%    in some other group. Thus, the best order of tests is to first
+%    test for 14, then for 0 and finally for 1 (simple group).
+% \changes{v1.0v}{2025/01/26}{Only migrate \cs{@doendpe} out of simple
+%    and semi-simple groups (gh1641)}
 %    \begin{macrocode}
-   \ifnum\currentgrouplevel>\z@
-      \aftergroup\propagate@doendpe
-   \fi
+  \ifnum\currentgrouptype =14        % semi-simple group
+    \aftergroup\propagate@doendpe
+  \else
+    \ifnum\currentgrouptype =\z@     % no group: top-level
+    \else
+      \ifnum\currentgrouptype =\@ne  % simple group
+        \aftergroup\propagate@doendpe
+     \fi
+    \fi
+  \fi
 }
 %    \end{macrocode}
 %    If \cs{if@endpe} is still true after the group ends, we run \cs{@doendpe}

base/testfiles/github-1641.lvt

@@ -0,0 +1,30 @@
+\documentclass{article}
+
+\input{test2e}
+
+\newcommand\sample{A text of more than a single line to see the paragraph indentation. Is this enough?}
+
+% show the group type we are dealing with
+
+\AddToHook{cmd/@endpetrue/before}{\showthe\currentgrouptype}
+
+\showoutput
+
+\begin{document}
+
+\START
+
+\sample
+
+\vbox{\hsize=3cm\noindent X}
+\sample \space Should be indented.
+
+\bigskip
+
+\vbox{\hsize=3cm\noindent 
+      \begin{itemize}\item X\end{itemize}}
+\sample Should be indented!
+
+\sample
+
+\end{document}