`\thmt@autoreffix` should do restoration globally

[muzimuzhi]

Description

Since both \@counteralias and cleveref's \@ynthm (when amsthm is loaded, see lines 2986--3024, especially line 3013) set \the<envname> globally, \thmt@autoreffix should also restore \the<envname> globally as well.

The difference is not sensible until package create-theorem uses \newtheorem in a group. Then the restoration in \thmt@autoreffix is cancelled after group.

Example and analysis

In example taken from https://tex.stackexchange.com/q/646129,

\documentclass{article}
\usepackage{amsthm}
\usepackage{thmtools}
\usepackage{create-theorem}

\CreateTheorem { theorem } {}

\begin{document}
\begin{theorem}
    Text.
\end{theorem}
\end{document}

• \CreateTheorem{theorem}{} first expands to \crthm_create_theorem:nn{theorem}{}, then calls

  \group_begin:
  \newtheorem {theorem_crthm_regional}[theorem]
    {\tl_use:c {g_crthm_name_heading_theorem_\languagename _tl}}
  \group_end:

• The remaining relevant stack trace looks like

  %% indent levels represent "stack trace"
  
  \group_begin: % create-theorem
  \newtheorem{<envname>}[<sibling>]{<thmname>} % thmtools redefined
    \thmt@newtheorem@predefinition
      \thmt@autorefsetup
        \@counteralias{<envname>}{<sibling>}
          \global\let\the<envname>\the<sibling>      %% <- A) global set
    \thmt@theoremdefiner{<envname>}[<envname>]{<thmname>}
      \@ynthm{<envname>}[<envname>]{<thmname>} % cleveref redefined
        \xdef\the<envname>{\noexpand\the<envname>}   %% <- B) global set
    \thmt@newtheorem@postdefinition
      \thmt@autoreffix
        \let\the<envname>\the<sibling>               %% <- C) local restoration
  \group_end: % create-theorem

  • Problem: Steps A and B are global while C is local, hence C is canceled after group.

Proposal

diff --git a/source/thm-autoref.dtx b/source/thm-autoref.dtx
index cf84463..850d171 100644
--- a/source/thm-autoref.dtx
+++ b/source/thm-autoref.dtx
@@ -33,7 +33,7 @@
   \ifthmt@hassibling
     \@counteralias{\thmt@envname}{\thmt@sibling}%
     \@xa\def\@xa\thmt@autoreffix\@xa{%
-      \@xa\let\csname the\thmt@envname\@xa\endcsname
+      \@xa\global\@xa\let\csname the\thmt@envname\@xa\endcsname
         \csname the\thmt@sibling\endcsname
       \def\thmt@autoreffix{}%
     }%