T73 Added virtual final destructors in CMeasurementUnit derived classes.

This fixes the GCC warning "deleting polymorphic object with non-virtual destructor".
They are marked final so the virtual dispatch can be optimized out, because they don't need to be overridden.

src/blackmisc/pq/units.h

@@ -68,6 +68,9 @@ namespace BlackMisc
             //! Null constructor
             CLengthUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CLengthUnit() final = default;
+
             //! Default unit
             static CLengthUnit defaultUnit() { return m(); }
 
@@ -178,6 +181,9 @@ namespace BlackMisc
             //! Null constructor
             CAngleUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CAngleUnit() final = default;
+
             //! Default unit
             static CAngleUnit defaultUnit() { return deg(); }
 
@@ -271,6 +277,9 @@ namespace BlackMisc
             //! Null constructor
             CFrequencyUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CFrequencyUnit() final = default;
+
             //! Default unit
             static CFrequencyUnit defaultUnit() { return Hz(); }
 
@@ -357,6 +366,9 @@ namespace BlackMisc
             //! Null constructor
             CMassUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CMassUnit() final = default;
+
             //! Default unit
             static CMassUnit defaultUnit() { return kg(); }
 
@@ -453,6 +465,9 @@ namespace BlackMisc
             //! Null constructor
             CPressureUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CPressureUnit() final = default;
+
             //! Default unit
             static CPressureUnit defaultUnit() { return hPa(); }
 
@@ -570,6 +585,9 @@ namespace BlackMisc
             //! Null constructor
             CTemperatureUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CTemperatureUnit() final = default;
+
             //! Default unit
             static CTemperatureUnit defaultUnit() { return C(); }
 
@@ -650,6 +668,9 @@ namespace BlackMisc
             //! Null constructor
             CSpeedUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CSpeedUnit() final = default;
+
             //! Default unit
             static CSpeedUnit defaultUnit() { return m_s(); }
 
@@ -754,6 +775,9 @@ namespace BlackMisc
             //! Null constructor
             CTimeUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CTimeUnit() final = default;
+
             //! Default unit
             static CTimeUnit defaultUnit() { return s(); }
 
@@ -879,6 +903,9 @@ namespace BlackMisc
             //! Null constructor
             CAccelerationUnit(std::nullptr_t) : CMeasurementUnit(nullUnit()) {}
 
+            //! Destructor
+            virtual ~CAccelerationUnit() final = default;
+
             //! Default unit
             static CAccelerationUnit defaultUnit() { return m_s2(); }