How to Implement a Plugin System in Rust

Rust does not support compiler plugins; the feature was removed and replaced by procedural macros. Use a procedural macro crate to extend the compiler's behavior at compile time.

// In Cargo.toml
[lib]
proc-macro = true

// In src/lib.rs
use proc_macro::TokenStream;

#[proc_macro]
pub fn my_plugin(input: TokenStream) -> TokenStream {
    // Transform input tokens here
    input
}

Rust used to allow external libraries to modify how the compiler works, but that feature is gone. Now, you use procedural macros to generate code or transform your code before it compiles. Think of it like a pre-processor that runs automatically to add features to your project.