E0277 rust type_error ai_generated true

error[E0277]: `Rc<dyn Trait>` cannot be sent between threads safely

ID: rust/e0277-trait-bound-send-not-satisfied-for-rc

Also available as: JSON · Markdown · 中文
90%Fix Rate
85%Confidence
1Evidence
2024-02-15First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Rust 1.75.0 active — — —
Rust 1.80.0 active — — —
Rust nightly 2024-01-01 active — — —

Root Cause

Rc is not Send because it uses reference counting without atomic operations, making it unsafe to share across threads.

generic

中文

Rc 使用非原子引用计数，无法在线程间安全共享，因此未实现 Send trait。

Official Documentation

https://doc.rust-lang.org/stable/error_codes/E0277.html

Workarounds

  1. 95% success Replace `Rc<dyn Trait>` with `Arc<dyn Trait>` which uses atomic reference counting and implements Send 
    Replace `Rc<dyn Trait>` with `Arc<dyn Trait>` which uses atomic reference counting and implements Send
  2. 85% success Use `std::sync::Mutex<Box<dyn Trait>>` if you need mutable access from multiple threads 
    Use `std::sync::Mutex<Box<dyn Trait>>` if you need mutable access from multiple threads

中文步骤

  1. Replace `Rc<dyn Trait>` with `Arc<dyn Trait>` which uses atomic reference counting and implements Send
  2. Use `std::sync::Mutex<Box<dyn Trait>>` if you need mutable access from multiple threads

Dead Ends

Common approaches that don't work:

  1. Wrap Rc in a Mutex: `Mutex<Rc<dyn Trait>>` 90% fail

    Mutex only provides interior mutability, not Send. Rc still prevents Send because the reference count isn't atomic.

  2. Add `unsafe impl Send for MyType` manually 95% fail

    Unsafe impl can cause data races and undefined behavior if Rc is actually used across threads; the compiler warning is legitimate.