How to programmatically compile Rust programs?

Question

Given metadata about the library I am trying to create in the form of an expression tree, I would like to be able to convert this into some sort of Rust-specific syntax tree that can be given to the Rust compiler.

I found a related question but it is outdated.

Answer 1

Yes there is. The Rust compiler itself. The entire compiler is a library and rustc is just a small crate that calls into the compiler. As an example there's the stupid-stats crate. It runs the rust compiler to generate some statistics about the code.

All you need is to import the rustc and rustc_driver crates (with extern crate) and implement the rustc_driver::CompilerCalls trait for a type (lets call it MyDriver). Then you can run rustc like this:

let args: Vec<_> = std::env::args().collect();
let mut my_driver = MyDriver::new();
rustc_driver::run_compiler(&args, &mut my_driver);

You need to make sure that the path to the standard library and core library is passed. In my case I added

"-L $HOME/.multirust/toolchains/nightly/lib/rustlib/x86_64-unknown-linux-gnu/lib"

to the command line. You cannot simply add this to the args vector, because $HOME isn't parsed here. So you need some more code that extracts the $HOME env var and builds your command.