A command line tool called rustup is used to install the rust compiler and associated tools on your system.

Tools installed by rustup command line tool are installed on the Cargo/bin directory

rustc is the Rust compiler. It's the software that takes your Rust source code as input and produces executable programs.

To create a Rust compiler that can target the MSVC (Microsoft Visual C++) ABI, which is used by some Windows software, the developers of Rust use the Microsoft Visual C++ compiler (a separate software tool) to compile the Rust compiler itself (rustc).

To put it simply, the Rust developers use the Microsoft Visual C++ compiler to compile the Rust compiler (rustc) so that it can generate Windows executables that are compatible with the MSVC ABI. This allows Rust programs to interoperate effectively with software produced by Visual Studio or other MSVC-compiled libraries on the Windows platform.

During the development and build process of the Rust compiler (rustc), the Rust project may use MSVC to compile certain components of the Rust compiler itself. This is done to ensure that the Rust compiler is compatible with the MSVC ABI (Application Binary Interface), which is used by some Windows software.

In the context of programming and compilers, ABI (Application Binary Interface) refers to the low-level interface between different parts of a compiled program. It specifies how functions, data structures, and system calls should be represented in binary form and how they interact with the operating system and other software components.

Here's why ABI matters in the context of Rust, especially on Windows, and how it can affect interoperability:

ABI Compatibility: Different compilers and toolchains can generate code with different ABIs. For example, MSVC (Microsoft Visual C++) and GCC (GNU Compiler Collection) have different ABIs on Windows.

Rust Compiler and ABI: The Rust compiler (rustc) generates code that adheres to a specific ABI. When you compile Rust code, the resulting binary (executable or library) follows this ABI.

Interop with Other Software: If your Rust code needs to interoperate with other software or libraries, it's crucial that they share the same ABI. If they don't, it can lead to compatibility issues, crashes, or undefined behavior.

Windows ABI: On Windows, the two main ABIs in use are the MSVC ABI (used by software compiled with Microsoft Visual C++) and the GNU ABI (used by software compiled with GCC, MinGW, or MSYS2).

If you compile your Rust code with the MSVC toolchain, it generates code that follows the MSVC ABI.

If you compile your Rust code with the GNU toolchain (e.g., MinGW), it generates code that follows the GNU ABI.

Here's what happens when you use the Rust compiler that was built with the GNU toolchain (e.g., MinGW) and potential interoperability issues:

Using Rust with the GNU Toolchain: If you use a Rust compiler that was built with the GNU toolchain (e.g., Rust on MinGW), it means your Rust code will produce binaries following the GNU ABI.

Interop Issues: Interoperability issues can arise when you want to use Rust code with other Windows software or libraries that were compiled with the MSVC toolchain. The mismatched ABIs can lead to problems like function call mismatches, data structure incompatibility, and runtime crashes.

Potential Solutions: To address interoperability issues, you might need to:

Use Rust libraries or bindings specifically built for the MSVC ABI when interfacing with MSVC-compiled software.

Use tools like C-compatible FFI (Foreign Function Interface) or libraries like libc to bridge the gap between Rust and C/C++ code, ensuring that the function signatures and data structures match the expected ABI.

In some cases, you might need to recompile your Rust code using the MSVC toolchain to ensure compatibility with specific Windows software.

It's essential to be aware of the ABI used by your Rust compiler and consider it when working with other software components, especially on platforms like Windows, where multiple ABIs are in use. Understanding the ABI helps ensure smooth interoperability between different parts of your software stack.

Rust developers often need to interoperate with other software libraries and systems to enhance the capabilities of their Rust applications. Here are some common types of software and libraries that Rust developers may need to interoperate with:

C and C++ Libraries: Rust has a Foreign Function Interface (FFI) that allows you to call functions from C and C++ libraries directly. Many system libraries and performance-critical libraries are written in C and C++. Examples include libraries for graphics, audio, networking, and system-level operations.

Web APIs: Rust is often used for web development, and Rust applications may need to interact with web services and APIs using HTTP libraries such as reqwest or WebSocket libraries like tokio-tungstenite.

Database Systems: Rust applications frequently need to connect to databases. Libraries like diesel, sqlx, and rusqlite provide database support for popular databases like PostgreSQL, MySQL, SQLite, and others.

GUI Frameworks: To build graphical user interfaces (GUIs), Rust developers may use GUI libraries like druid, gtk, qt, or interoperate with existing C/C++ GUI libraries through FFI.

Cryptographic Libraries: For encryption and security-related tasks, Rust developers may use cryptographic libraries like ring or interoperate with OpenSSL.

These are just a few examples, and the choice of libraries and systems to interoperate with depends on the specific requirements of the Rust project. Rust's strong FFI capabilities and the availability of bindings to C/C++ libraries make it possible to integrate with a wide range of software and systems.