How can I use rustc_interface::run_compiler to sava type information?

compiler
1

I am extracting some source code information for code mutation and generation based on rustc's library. I'm using the rustc_interface::run_compiler closure to parse the MIR and get the type information I need, how can I store it and use outside the closure?

It looks like rustc_interface::run_compiler is multithreaded, so how do I change it to single threaded? Or is there a better way to save Ty<'_> and use it in other place?

Below is my code:

let tys = rustc_interface::run_compiler(config, |compiler| {
        let tys  = compiler.enter(|queries| {
            let mut tys = Vec::new();
            queries.global_ctxt().unwrap().enter(|tcx| {
                let hir_krate = tcx.hir();
                for id in hir_krate.items() {
                    let item = id.owner_id.def_id;
                    match tcx.def_kind(item) {
                        def::DefKind::Fn => {
                            let mir: &rustc_middle::mir::Body<'_> = tcx.optimized_mir(item);
                            let return_ty = mir.local_decls[rustc_middle::mir::Local::from_usize(0)].ty;
                            tys.push(return_ty);
                            println!("{:?}", return_ty);
                        },
                        _ => {}
                    }
                }
            });
            tys
        });
        tys
    });

This is the error information:

error[E0277]: Span cannot be shared between threads safely

--> src/main.rs:49:15

| 49 | let tys = rustc_interface::run_compiler(config, |compiler| {

| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Span cannot be shared between threads safely

|

= help: within BoundVariableKind, the trait std::marker::Sync is not implemented for Span

= note: required because it appears within the type Option<Span>

= note: required because it appears within the type BoundRegionKind

= note: required because it appears within the type BoundVariableKind

= note: required for List<BoundVariableKind> to implement std::marker::Sync

= note: required because it appears within the type &List<BoundVariableKind>

= note: required because it appears within the type Binder<'_, FnSig<'_>>

= note: required because it appears within the type TyKind<TyCtxt<'_>>

= note: required because it appears within the type WithCachedTypeInfo<TyKind<TyCtxt<'_>>>

= note: required for &WithCachedTypeInfo<rustc_type_ir::TyKind<TyCtxt<'_>>> to implement Send

= note: required because it appears within the type Interned<'_, WithCachedTypeInfo<TyKind<TyCtxt<'_>>>>

= note: required because it appears within the type Ty<'_>

= note: required for std::ptr::Unique<rustc_middle::ty::Ty<'_>> to implement Send

= note: required because it appears within the type RawVec<Ty<'_>>

= note: required because it appears within the type Vec<Ty<'_>>

note: required by a bound in run_compiler