Fix E0075: Generator/Resume Point Cannot Exist in a Const Context

Wed, 22 Jul 2026 17:32:04 +0800

1. Symptoms

When the Rust compiler encounters E0075, you will see an error message similar to the following during compilation:

error[E0075]: generator/resume point cannot exist in a `const` context
 --> src/main.rs:5:5
  |
5 |     let result = gen.resume();
  |     ^^^^^^^^^^^^^^^^^^^^^^^^

The error indicates that a generator or coroutine’s .resume() method is being invoked in a context that the compiler treats as requiring compile-time evaluation. This typically manifests in const functions, const blocks, or during constant promotion scenarios. The compiler flag E0075 specifically targets the attempt to advance a generator’s state at a point where only compile-time computations are permitted.

Fix E0770: Async Fn Return Type Cannot Contain Impl Trait

Mon, 15 Jun 2026 10:20:04 +0800

Fix E0770: Async Fn Return Type Cannot Contain `impl Trait`

Rust’s async fn syntax provides a convenient way to write asynchronous code, but it comes with strict limitations on what return types are allowed. Error E0770 is a compile-time error that occurs when developers attempt to use impl Trait in the return type of an async fn. Understanding why this restriction exists and how to work around it is essential for writing idiomatic async Rust code.

Generators on ErrorVault — Developer Error Code Dictionary

Fix E0075: Generator/Resume Point Cannot Exist in a Const Context

1. Symptoms

Fix E0770: Async Fn Return Type Cannot Contain Impl Trait

Fix E0770: Async Fn Return Type Cannot Contain impl Trait

Fix E0770: Async Fn Return Type Cannot Contain `impl Trait`