Integrating a C Library with Rust using bindgen

This challenge focuses on using bindgen to generate Rust bindings for a simple C library. bindgen is a powerful tool that automatically generates Rust code from C header files, allowing you to seamlessly interact with existing C code from your Rust projects. This is a common task when leveraging mature C libraries or integrating with systems written in C.

Problem Description

You are tasked with creating a Rust project that utilizes bindgen to generate bindings for a provided C library. The C library, libsimplemath.h, provides a single function: add(a, b), which takes two integers as input and returns their sum. Your Rust code should call this add function and print the result to the console.

What needs to be achieved:

1. Create a new Rust project.
2. Write a libsimplemath.h file (provided below) representing a simple C library.
3. Use bindgen to generate Rust bindings from libsimplemath.h.
4. Write Rust code that includes the generated bindings and calls the add function.
5. Compile and run the Rust code, verifying that it correctly calls the C function and prints the sum of two numbers.

Key requirements:

• The generated Rust bindings must correctly expose the add function from the C library.
• The Rust code must be able to call the add function without errors.
• The output of the Rust program should be the sum of the two input numbers.

Expected behavior:

When the Rust program is executed, it should call the add function with the arguments 5 and 3, and print the result (8) to the console.

Edge cases to consider:

• Ensure the bindgen configuration is correct to handle the C header file properly.
• Handle potential errors during the linking process. While this challenge doesn't explicitly require error handling, be mindful of it.

Examples

Example 1:

Input: libsimplemath.h contains:
```c
#ifndef SIMPLEMATH_H
#define SIMPLEMATH_H

int add(int a, int b);

#endif

// Rust code calling the add function

Output:

8

Explanation: The Rust code uses bindgen to generate bindings for the add function in libsimplemath.h. It then calls add(5, 3) and prints the returned value (8) to the console.

Constraints

• The C library (libsimplemath.h) is provided and should not be modified.
• The Rust code must compile and run without external dependencies beyond bindgen and the standard library.
• The solution should be concise and readable.
• The add function should be called with the arguments 5 and 3.

Notes

• You'll need to install bindgen as a dependency in your Cargo.toml file.
• Consider using a build script (build.rs) to automate the bindgen process. This is the recommended approach for integrating bindgen into a Rust project.
• The C library itself doesn't need to be compiled into a shared library for this exercise; bindgen only needs the header file. The linking will happen during the Rust compilation.
• Pay close attention to the bindgen configuration to ensure the correct types are generated for the C function arguments and return value.

libsimplemath.h:

#ifndef SIMPLEMATH_H
#define SIMPLEMATH_H

int add(int a, int b);

#endif