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rust.error_result_unused

Correctness High

Detects Result values that are ignored without handling errors.

Why It Matters

Ignored Results:

Silent failures — Errors go unnoticed
Data loss — Operations fail without warning
Hard to debug — No error trail

Example

// ❌ Before (Result ignored)
fn save_config(config: &Config) {
    std::fs::write("config.json", serde_json::to_string(config).unwrap());
    // Returns Result, but we ignore it!
}

// ✅ After (Result handled)
fn save_config(config: &Config) -> Result<(), Error> {
    std::fs::write("config.json", serde_json::to_string(config)?)?;
    Ok(())
}

// Or explicitly acknowledge:
fn save_config_best_effort(config: &Config) {
    let _ = std::fs::write("config.json", serde_json::to_string(config).unwrap_or_default());
    // `let _ =` shows intentional discard
}

What Unfault Detects

Function calls returning Result without handling
Missing ? operator propagation
Result assigned but never checked

Auto-Fix

Unfault can add ? operator or explicit let _ = acknowledgment.