Assert in-bounds access when using operator[]

Out of bounds array access is undefined behavior so let's be sure
to catch potential UB in debug builds. It's too easy to accidentally
provide an invalid index to one of these public APIs.

src/SFML/Graphics/ConvexShape.cpp

@@ -27,6 +27,8 @@
 ////////////////////////////////////////////////////////////
 #include <SFML/Graphics/ConvexShape.hpp>
 
+#include <cassert>
+
 
 namespace sf
 {
@@ -55,6 +57,7 @@ std::size_t ConvexShape::getPointCount() const
 ////////////////////////////////////////////////////////////
 void ConvexShape::setPoint(std::size_t index, const Vector2f& point)
 {
+    assert(index < m_points.size() && "Index is out of bounds");
     m_points[index] = point;
     update();
 }
@@ -63,6 +66,7 @@ void ConvexShape::setPoint(std::size_t index, const Vector2f& point)
 ////////////////////////////////////////////////////////////
 Vector2f ConvexShape::getPoint(std::size_t index) const
 {
+    assert(index < m_points.size() && "Index is out of bounds");
     return m_points[index];
 }
 

src/SFML/Graphics/VertexArray.cpp

@@ -28,6 +28,8 @@
 #include <SFML/Graphics/RenderTarget.hpp>
 #include <SFML/Graphics/VertexArray.hpp>
 
+#include <cassert>
+
 
 namespace sf
 {
@@ -51,6 +53,7 @@ std::size_t VertexArray::getVertexCount() const
 ////////////////////////////////////////////////////////////
 Vertex& VertexArray::operator[](std::size_t index)
 {
+    assert(index < m_vertices.size() && "Index is out of bounds");
     return m_vertices[index];
 }
 
@@ -58,6 +61,7 @@ Vertex& VertexArray::operator[](std::size_t index)
 ////////////////////////////////////////////////////////////
 const Vertex& VertexArray::operator[](std::size_t index) const
 {
+    assert(index < m_vertices.size() && "Index is out of bounds");
     return m_vertices[index];
 }
 

src/SFML/System/String.cpp

@@ -31,6 +31,7 @@
 #include <iterator>
 #include <utility>
 
+#include <cassert>
 #include <cstring>
 
 
@@ -213,6 +214,7 @@ String& String::operator+=(const String& right)
 ////////////////////////////////////////////////////////////
 char32_t String::operator[](std::size_t index) const
 {
+    assert(index < m_string.size() && "Index is out of bounds");
     return m_string[index];
 }
 
@@ -220,6 +222,7 @@ char32_t String::operator[](std::size_t index) const
 ////////////////////////////////////////////////////////////
 char32_t& String::operator[](std::size_t index)
 {
+    assert(index < m_string.size() && "Index is out of bounds");
     return m_string[index];
 }