Fix E0615: Attempted to Derive an Impl of a Trait That Is Not Derivable

Sun, 26 Jul 2026 10:20:04 +0800

1. Symptoms

When you encounter Rust error E0615, the compiler produces output similar to the following:

error[E0615]: attempted to derive an impl of a trait that is not marked `#[derivable]`
  --> src/main.rs:5:12
   |
5  | #[derive(MyCustomTrait)]
   |            ^^^^^^^^^^^^^
   |
   = note: only traits marked with `#[derivable]` can be derived

The error manifests at the specific line where the #[derive(...)] attribute is applied to a struct or enum definition. The compiler rejects the derivation request because the specified trait is not recognized as derivable by the Rust compiler’s built-in derive mechanism. This error typically surfaces during the compilation phase when the compiler attempts to expand the derive macro and discovers that the target trait lacks the necessary metadata to support automatic implementation generation.

Trait-Derivation on ErrorVault — Developer Error Code Dictionary

Fix E0615: Attempted to Derive an Impl of a Trait That Is Not Derivable

1. Symptoms