The error reported is
```
[  6%] Building CXX object src/CMakeFiles/texmacs_body.dir/Data/Convert/Generic/generic.cpp.o
In file included from /builddir/build/BUILD/TeXmacs-2.1.2-build/TeXmacs-2.1.2-src/src/Kernel/Containers/hashtree.hpp:126,
                 from /builddir/build/BUILD/TeXmacs-2.1.2-build/TeXmacs-2.1.2-src/src/Data/String/converter.hpp:15:
/builddir/build/BUILD/TeXmacs-2.1.2-build/TeXmacs-2.1.2-src/src/Kernel/Containers/hashtree.cpp: In member function ‘hashtree<K, V> hashtree<K, V>::operator[](K)’:
/builddir/build/BUILD/TeXmacs-2.1.2-build/TeXmacs-2.1.2-src/src/Kernel/Containers/hashtree.cpp:97:14: error: ‘class hashtree<K, V>’ has no member named ‘contains’ [-Wtemplate-body]
   97 |   if (*this->contains (key)) return *this->children (key);
      |              ^~~~~~~~
/builddir/build/BUILD/TeXmacs-2.1.2-build/TeXmacs-2.1.2-src/src/Kernel/Containers/hashtree.cpp:97:44: error: ‘class hashtree<K, V>’ has no member named ‘children’ [-Wtemplate-body]
   97 |   if (*this->contains (key)) return *this->children (key);
      |                                            ^~~~~~~~
```

Could be a gcc-15 issue

Reproducible: Always