https://errorvault.dev/tags/e0643/ Recent content in E0643 on ErrorVault — Developer Error Code Dictionary Hugo en-us Sat, 25 Jul 2026 00:44:04 +0800 https://errorvault.dev/rust/rust-e0643-const-generic-body-evaluation/ Sat, 25 Jul 2026 00:44:04 +0800 https://errorvault.dev/rust/rust-e0643-const-generic-body-evaluation/ <h1 id="fix-e0643-generic-const-parameters-cannot-be-used-in-function-body">Fix E0643: Generic Const Parameters Cannot Be Used in Function Body</h1> <p>Rust&rsquo;s const generics feature enables writing code that is generic over constant values, allowing types like <code>Vec&lt;N&gt;</code> where <code>N</code> is a compile-time integer. However, the compiler imposes strict restrictions on what operations can be performed on const generic parameters inside function bodies. Error E0643 is emitted when a const generic parameter is used in a way that the compiler cannot evaluate at compile time, making it impossible to monomorphize the function for a given set of generic arguments.</p>