Rust crate: how to send SourceFile between threads? Lrc<String> is preventing this for me

[alshdavid]

I am writing a bundler. Trying to parse a bunch of source files in parallel then store the resulting Modules and SourceFiles in Mutex protected containers before mutating/combining them in a following phase. My code looks roughly like:

let module_map = Arc::new(Mutex::new(HashMap::<PathBuf, Module>::new()));
let source_map = Arc::new(Mutex::new(SourceMap::default()));
let sources = Vec::<(PathBuf, String)>::new();

// Phase 1: crawl and parse sources - not doing that in this example
thread::spawn(move || {
    for (file_path, source_code) in sources.iter() {
        let source_file = source_map.lock().unwrap().new_source_file(
            FileName::Real(file_path.clone()), source_code.into(),
        );

        let syntax = Syntax::Typescript(TsConfig::default());
        let lexer = Lexer::new(syntax, Default::default(), StringInput::from(&*source_file), None);
        let mut parser = Parser::new_from(lexer);
    
        let module = parser.parse_module().unwrap();

        module_map.lock().unwrap().insert(file_path.clone(), module);
    }
}).join().unwrap();

However I am getting the error:

`Lrc<std::string::String>` cannot be sent between threads safely
within `SourceFile`, the trait `std::marker::Send` is not implemented for `Lrc<std::string::String>`

How am I supposed to use SourceFile in a multithreaded context?

[kwonoj]

swc/crates/swc_common/src/sync.rs

Line 11 in cf9e865

//! This module defines types which are thread safe if `cfg!(feature =