https://errorvault.dev/tags/feature-gates/ Recent content in Feature-Gates on ErrorVault — Developer Error Code Dictionary Hugo en-us Tue, 04 Aug 2026 22:20:04 +0800 https://errorvault.dev/rust/rust-e0727-async-closures-not-stable/ Tue, 04 Aug 2026 22:20:04 +0800 https://errorvault.dev/rust/rust-e0727-async-closures-not-stable/ <h2 id="1-symptoms">1. Symptoms</h2> <p>When attempting to compile Rust code that uses <code>async</code> closures, the compiler produces error E0727. The error manifests with a clear diagnostic message indicating that async closures are not yet stable. Developers typically encounter this when writing code that attempts to combine closure syntax with the <code>async</code> keyword.</p> <p>The error appears in several common scenarios: when passing an async closure to a higher-order function expecting a callable that returns a future, when trying to chain async operations inside closure bodies, or when refactoring synchronous code to use async patterns while using closure syntax. The compiler output typically shows the file path, line number, and a message stating that async closures are not yet stable and require the <code>async_closure</code> feature gate to be enabled.</p>