`cleveref` 引用名称不正确

上面的代码其实cleverref会报警告：

LaTeX Warning: Reference `lem' on page 1 undefined on input line 18.
LaTeX Warning: Reference `lem' on page 1 undefined on input line 18.

此事在下面的几个链接里都有记载：

• https://tex.stackexchange.com/a/730164/322482
• https://tex.stackexchange.com/a/735502/322482
• https://tex.stackexchange.com/questions/747380/cleveref-not-referring-correctly-to-a-theorem#comment1863469_747380

目前来看的最佳实践似乎是：

\documentclass{article}
\usepackage{amsthm}
\usepackage{cleveref}
\newtheorem{thm}{Theorem}[section]
\newtheorem{lem}[thm]{Lemma}
\AddToHook{env/lem/begin}{\crefalias{thm}{lem}}

\crefname{lem}{lemma}{lemmas}
\Crefname{lem}{Lemma}{Lemmas}
\begin{document}
  \begin{thm}\label{thm}
    foo
  \end{thm}
  \begin{lem}\label{lem}
    foo
  \end{lem}
  \noindent
  \cref{lem}, \Cref{lem}
\end{document}

似乎在firstaid中已经修了...但我不太懂这个...

最后补充一下「我本地TL2025会出问题」的内核和宏包版本(\listfiles)：

 *File List*
 article.cls    2025/01/22 v1.4n Standard LaTeX document class
  size10.clo    2025/01/22 v1.4n Standard LaTeX file (size option)
  amsthm.sty    2020/05/29 v2.20.6
cleveref.sty    2018/03/27 v0.21.4 Intelligent cross-referencing
l3backend-pdftex.def    2025-04-14 L3 backend support: PDF output (pdfTeX)

其实还有一个办法可以解决，但是麻烦一些。

\documentclass{article}
\usepackage{amsthm}
\usepackage{cleveref}
\newtheorem{thm}{Theorem}[section]
\newtheorem{lem}[thm]{Lemma}

\begin{document}
  \begin{thm}\label{thm}
    foo
  \end{thm}
  \begin{lem}\label[lem]{lem}
    foo
  \end{lem}
  \cref{lem}, \Cref{lem}
\end{document}

如果换用别的包，可以这样做

\documentclass{article}
\usepackage{amsthm}
\usepackage{zref-clever}

\AddToHook{env/thm/begin}{\zcsetup{countertype={thm = theorem}}}
\AddToHook{env/lem/begin}{\zcsetup{countertype={thm = lemma}}}

\newtheorem{thm}{Theorem}[section]
\newtheorem{lem}[thm]{Lemma}

\begin{document}
  \begin{thm}\label{thm}
    foo
  \end{thm}

  \begin{lem}\label{lem}
    foo
  \end{lem}

  \zcref{lem}
\end{document}

这里的 theorem 和 lamma 都是 zref-clever 支持的已知类型，如果是未知类型，还可以做类似如下的设置

\zcRefTypeSetup{experiment}{
  Name-sg= Experiment,
  name-sg= experiment,
  Name-pl= Expariments,
  name-pl= experiments,
  Name-sg-ab= Expr.,
  name-sg-ab= expr.,
  Name-pl-ab= Exprs.,
  name-pl-ab= exprs.
}

然后就可以

\AddToHook{env/expr/begin}{\zcsetup{countertype={expr = experiment}}}
\newtheorem{expr}{Experiment}

仅从这个问题来看，zref-clever 仿佛并未打开多少便利，但已经很多人都换成这个包了，我姑且也慢慢适应吧