Changed 'Does nothing' comment to 'Undefined behavior'

src/ibasic_string.h

@@ -460,14 +460,15 @@ namespace etl
 
     //*************************************************************************
     /// Removes an element from the end of the string.
-    /// Does nothing if the string is empty.
+    /// Undefined behaviour if the string is empty.
     //*************************************************************************
     void pop_back()
     {
-      if (current_size > 0)
-      {
-        p_buffer[--current_size] = 0;
-      }
+#if defined(ETL_CHECK_PUSH_POP)
+      ETL_ASSERT(!empty(), ETL_ERROR(string_empty));
+#endif
+
+      p_buffer[--current_size] = 0;
     }
 
     //*********************************************************************

src/ipriority_queue.h

@@ -180,17 +180,14 @@ namespace etl
 
     //*************************************************************************
     /// Removes the oldest value from the back of the priority queue.
-    /// Does nothing if the priority queue is already empty.
+    /// Undefined behaviour if the priority queue is already empty.
     //*************************************************************************
     void pop()
     {
-      if (!empty())
-      {
-        // Move largest element to end
-	      std::pop_heap(container.begin(), container.end(), TCompare());
-        // Actually remove largest element at end
-        container.pop_back();
-      }
+      // Move largest element to end
+      std::pop_heap(container.begin(), container.end(), TCompare());
+      // Actually remove largest element at end
+      container.pop_back();
     }
 
     //*************************************************************************

src/iqueue.h

@@ -162,7 +162,7 @@ namespace etl
 
     //*************************************************************************
     /// Removes the oldest value from the back of the queue.
-    /// Does nothing if the queue is already empty.
+    /// Undefined behaviour if the queue is already empty.
     //*************************************************************************
     void pop()
     {

src/istack.h

@@ -135,7 +135,7 @@ namespace etl
 
     //*************************************************************************
     /// Removes the oldest item from the top of the stack.
-    /// Does nothing if the stack is already empty.
+    /// Undefined behaviour if the stack is already empty.
     //*************************************************************************
     void pop()
     {

src/ivector.h

@@ -475,7 +475,7 @@ namespace etl
 
     //*************************************************************************
     /// Removes an element from the end of the vector.
-    /// Does nothing if the vector is empty.
+    /// Undefined behaviour if the vector is empty.
     //*************************************************************************
     void pop_back()
     {