Protect against latexrelease loaded in another package

base/lthooks.dtx

@@ -1749,13 +1749,6 @@
 \tl_new:N \g_@@_hook_curr_name_tl
 \seq_new:N \g_@@_name_stack_seq
 %    \end{macrocode}
-%
-%    Inside \pkg{latexrelease} we also push something on the stack to
-%    support roll forward.
-% \changes{v1.0f}{2020/11/24}{Support for roll forward (gh/434)}
-%    \begin{macrocode}
-%<latexrelease>\seq_gpush:Nn \g__hook_name_stack_seq { }
-%    \end{macrocode}
 % \end{macro}
 %
 % \begin{macro}{\@@_tmp:w}
@@ -3892,23 +3885,42 @@
 %   current package/file to be used as label for hooks.
 %   Providing a consistent interface is tricky, because packages can
 %   be loaded within packages, and some packages may not use
-%   \cs{DeclareDefaultHookLabel} to change the default label (in which case
-%   \cs{@currname} is used, if set).
+%   \cs{DeclareDefaultHookLabel} to change the default label (in which
+%   case \cs{@currname} is used, if set).
 %
 %   To pull that off, we keep a stack that contains the default label
 %   for each level of input.  The bottom of the stack contains the
 %   default label for the top-level.  Since the string \verb|top-level|
-%   is hardcoded, here this item of the stack is empty.  Also, since
-%   we're in an input level, add \verb|lthooks| to the stack as well.
-%   This stack should never go empty.  An empty entry is added to the
+%   is hardcoded, here this item of the stack is empty.  This stack
+%   should never go empty.
+%
+%   But first, in case we're in \pkg{latexrelease} we push something on
+%   the stack to support roll forward.  But in some rare cases,
+%   \pkg{latexrelease} may be loaded inside another package (notably
+%   \pkg{platexrelease}), so we'll dissect the \cs{@currnamestack},
+%   adding empty items to the stack (empty so that defaults can kick in
+%   if needed):
+% \changes{v1.0f}{2020/11/24}{Support for roll forward (gh/434)}
+%    \begin{macrocode}
+%<latexrelease>\cs_set_protected:Npn \@@_tmp:w #1 #2 #3
+%<latexrelease>  {
+%<latexrelease>    \quark_if_recursion_tail_stop:n {#1}
+%<latexrelease>    \seq_gput_right:Nn \g_@@_name_stack_seq { }
+%<latexrelease>    \@@_tmp:w
+%<latexrelease>  }
+%<latexrelease>\exp_after:wN \@@_tmp:w \@currnamestack
+%<latexrelease>  \q_recursion_tail \q_recursion_tail
+%<latexrelease>  \q_recursion_tail \q_recursion_stop
+%    \end{macrocode}
+%
+%   Finally, an empty entry is added to the
 %   stack to account for the \verb|top-level|.  The item is empty so
 %   that the hard-coded default is used, but a call to
 %   \cs{DeclareDefaultHookLabel} will change it if needed.
 %    \begin{macrocode}
 \seq_gpush:Nn \g_@@_name_stack_seq { }
 %    \end{macrocode}
 %
-%
 %   Two commands keep track of the stack: when a file is input,
 %   \cs{@@_curr_name_push:n} pushes an (empty by default) label to the
 %   stack: