Rust Error E0725: Disallowed Feature Attribute

Understanding Rust Error E0725

Rust Error E0725 occurs when the compiler encounters a feature attribute that is not allowed by the compiler's command line flags. The error message indicates the offending feature attribute, and provides guidance on how to resolve the issue.

Example of Erroneous Code


In the example above, the feature 'never_type' is not included in the list of allowed features. This will trigger Rust Error E0725.

Resolving Rust Error E0725

To resolve Rust Error E0725, you can either remove the offending feature attribute from your code or add it to the list of allowed features using the '-Z allow_features' flag when running the compiler.

Removing the Offending Feature Attribute

If you decide to remove the feature attribute, simply delete the offending line from your code. In the example provided, this would entail removing the '#![feature(never_type)]' line.

Adding the Feature to the List of Allowed Features

If you want to enable the feature, you can add it to the allowed features list using the '-Z allow_features' flag. When using this flag, you need to specify the feature name:

rustc -Z allow_features=never_type main.rs

Keep in mind that the use of the '-Z' flag requires a nightly build of the Rust compiler, as it enables experimental features. Ensure you have a nightly build installed and are aware of the potential instability that may arise when using experimental features.