maths: add unary 'max'

maths.hpp

@@ -573,7 +573,19 @@ namespace cruft {
     }
 
 
-    //-------------------------------------------------------------------------
+    ///------------------------------------------------------------------------
+    /// Unary maximum provided to simplify application of max to template
+    /// parameter packs.
+    ///
+    /// eg, `max (sizeof (T)...)` will otherwise fail with a single type.
+    template <concepts::integral ValueT>
+    constexpr decltype(auto)
+    max (ValueT &&val)
+    {
+        return std::forward<ValueT> (val);
+    }
+
+
     /// Variadic maximum
     template <typename T, typename U, typename ...Args>
     constexpr std::enable_if_t<