Anyhow is a flexible error handling library for Rust that provides a trait object based Error type for idiomatic error propagation in applications.
The library solves the problem of ergonomic error handling in Rust by offering anyhow::Error as a return type that works seamlessly with the ? operator to propagate any error implementing std::error::Error. It allows developers to attach contextual information to low-level errors, making debugging easier by explaining what higher-level operation was underway when an error occurred. The tool supports downcasting errors by value, shared reference, or mutable reference as needed. When running on Rust 1.65 or later, backtraces are automatically captured and printed if the underlying error type does not provide its own, controlled through environment variables like RUST_BACKTRACE or RUST_LIB_BACKTRACE.
Anyhow suits any Rust application where you want straightforward error handling without defining custom error types for every function. It works with error types from any crate that implements std::error::Error, and one-off error messages can be constructed with the anyhow! macro or bail! macro for early returns. The library also supports no_std environments when the std feature is disabled, though a global allocator is required. Compared to failure, anyhow::Error is built on the standard library's std::error::Error trait rather than a separate trait, leveraging improvements adopted by the standard library itself.
The project maintains a clean, focused codebase with regular CI validation. Development activity shows consistent attention to compatibility across Rust versions, including special handling for older versions where certain trait functionality differs. The tool receives updates that address edge cases and maintain alignment with evolving Rust standards.
