From: Jan Engelhardt <ej@inai.de>
Date: 2026-02-03 16:06:43.440699815 +0100

With eigen-5.x, the build fails due to assumption of implicit inclusion of
assert.

```
[   26s] In file included from ~/avogadrolibs-1.100.0/avogadro/core/angleiterator.cpp:9:
[   26s] ~/avogadrolibs-1.100.0/avogadro/core/molecule.h: In member function ‘Avogadro::Index Avogadro::Core::Molecule::bondCount() const’:
[   26s] ~/avogadrolibs-1.100.0/avogadro/core/molecule.h:1115:3: error: ‘assert’ was not declared in this scope
[   26s]  1115 |   assert(m_graph.edgeCount() == m_bondOrders.size());
[   26s]       |   ^~~~~~
[   26s] ~/avogadrolibs-1.100.0/avogadro/core/molecule.h:23:1: note: ‘assert’
is defined in header ‘<cassert>’; this is probably fixable by adding ‘#include
<cassert>’
```

---
 avogadro/core/molecule.h |    1 +
 1 file changed, 1 insertion(+)

Index: avogadrolibs-1.100.0/avogadro/core/molecule.h
===================================================================
--- avogadrolibs-1.100.0.orig/avogadro/core/molecule.h
+++ avogadrolibs-1.100.0/avogadro/core/molecule.h
@@ -19,6 +19,7 @@
 #include "vector.h"
 
 #include <bitset>
+#include <cassert>
 #include <list>
 #include <map>
 #include <string>