Explain C++ References, Pointers, Virtual Methods, and Overrides

Scenario

In real-time, safety-critical systems like autonomous vehicles, precise control over memory semantics, object lifetimes, and dynamic polymorphism is critical. A subtle misunderstanding of references, pointer lifetimes, or dynamic dispatch can introduce memory leaks, cache misses, or undefined behavior.

Demonstrate your understanding of these core C++ mechanisms by analyzing the theoretical concepts and diagnosing issues in the provided code snippet.

Conceptual Requirements

Explain the following in detail:

1. Pointers vs. References: Compare syntax, memory representation, nullability, re-seating (reassignment), and lifetime hazards (e.g., dangling references vs. dangling pointers).
2. Virtual Functions and Dynamic Dispatch: Explain how compilers implement runtime polymorphism under the hood (specifically vptr and vtable), including memory layout per instance/class and execution overhead.
3. The override Specifier: Explain why C++11 introduced override, how it interacts with function signatures (e.g., parameter types, const qualifiers), and what happens when it is omitted.

Code Analysis

Review the following simplified sensor interface implementation, identify three critical bugs or architectural flaws, and write the corrected version of the classes.

#include 
#include 

class Sensor {
public:
    Sensor() = default;
    ~Sensor() { 
        std::cout << "Sensor destroyed\n"; 
    }

    virtual void configure() {
        std::cout << "Default sensor configuration\n";
    }

    virtual void processData(const double& timestamp) {
        std::cout << "Base processing at " << timestamp << "\n";
    }
};

class CameraSensor : public Sensor {
private:
    int* rawFrameBuffer;

public:
    CameraSensor() : rawFrameBuffer(new int[1024]) {}
    ~CameraSensor() {
        delete[] rawFrameBuffer;
        std::cout << "CameraSensor buffer freed\n";
    }

    // Intended to override base configure
    void configure() const {
        std::cout << "Camera customized configuration\n";
    }

    // Intended to override base processData
    void processData(double& timestamp) {
        std::cout << "Camera processing at " << timestamp << "\n";
    }
};

void runDiagnostics(Sensor s) {
    s.configure();
}

Explain the behavior of runDiagnostics when passed an instance of CameraSensor, what happens when a CameraSensor is deleted via a std::unique_ptr, and how compiler checks would prevent the signature mismatches in CameraSensor.