pow<N>() fixed to work with the integral representations

src/include/units/math.h

@@ -32,7 +32,7 @@ namespace units {
   {
     using dim = dimension_pow_t<typename U::dimension, N>;
     using r = ratio_pow<typename U::ratio, N>;
-    return quantity<downcast_traits_t<unit<dim, r>>, Rep>(std::pow(q.count(), N));
+    return quantity<downcast_traits_t<unit<dim, r>>, Rep>(static_cast<Rep>(std::pow(q.count(), N)));
   }
 
   template<typename U, typename Rep>
@@ -40,7 +40,7 @@ namespace units {
   {
     using dim = dimension_sqrt_t<typename U::dimension>;
     using r = ratio_sqrt<typename U::ratio>;
-    return quantity<downcast_traits_t<unit<dim, r>>, Rep>(std::sqrt(q.count()));
+    return quantity<downcast_traits_t<unit<dim, r>>, Rep>(static_cast<Rep>(std::sqrt(q.count())));
   }
 
 }  // namespace units

test/unit_test/test_quantity.cpp

@@ -22,6 +22,8 @@
 
 #include "units/dimensions/velocity.h"
 #include "units/dimensions/frequency.h"
+#include "units/dimensions/area.h"
+#include "units/math.h"
 #include <utility>
 #include <chrono>
 
@@ -130,8 +132,7 @@ namespace {
   static_assert([]() {
     quantity<metre, int> l1(1), l2(2);
     return l2 = l1;
-  }()
+  }().count() == 1);
-                    .count() == 1);
 
   // static member functions
 
@@ -281,4 +282,6 @@ namespace {
   static_assert(2kmph * 2h == 4km);
   static_assert(2km / 2kmph == 1h);
 
+  static_assert(std::is_same_v<decltype(pow<2>(2m)), decltype(4sq_m)>);
+
 }  // namespace