Code Smell 292 - Missing Return

When your code loses its way

TL;DR: Missing return statements cause unexpected behavior.

Problems 😔

• Silent failures
• Unreliable results
• Hard debugging
• Inconsistent and misleading behavior
• Broken logic

Solutions 😃

1. Always return values
2. Use clear flow
3. Validate conditions
4. Test all return paths
5. Use early returns
6. Remove IFs

Refactorings ⚙️

Context 💬

When you forget to return a value, your function keeps executing and your app might show incomplete or wrong information.

Sample Code 📖

Wrong ❌

fun totalDistance(activity: Activity): Double {
    if (activity.type == "Running") {
        activity.calculateDistance() 
        // Missing return here
    } else {
        return 0.0
    }
    // Other options are omitted for simplicity
    // Some languages raise a runtime error 
    // If the function does not return a value
    // of the correct type (in this case a Double)
}

Right 👉

fun totalDistance(activity: Activity): Double {
    if (activity.type == "Running") {
        return activity.calculateDistance() 
        // Now it returns the value
    } else {
        return 0.0
    }
}

Detection 🔍

• [x]Automatic

You can detect this smell when your function lacks a return statement in certain branches.

Most static analyzers and linters often catch this.

Tags 🏷️

• IFs

Level 🔋

• [x]Beginner

Why the Bijection Is Important 🗺️

it's important to maintain a clear and predictable relationship between your code and the Real World.

If a function is intended to calculate and return a value, it should always do so.

Failing to return a value breaks the MAPPER, leading to inaccurate behavior and unreliable results.

AI Generation 🤖

AI tools usually don't generate this smell.

AI Detection 🥃

Most AI-powered linters quickly catch missing returns with static analysis or by examining your code's Abstract Syntax Tree.

Try Them! 🛠

Remember: AI Assistants make lots of mistakes

Without Proper Instructions	With Specific Instructions
ChatGPT	ChatGPT
Claude	Claude
Perplexity	Perplexity
Copilot	Copilot
Gemini	Gemini
DeepSeek	DeepSeek
Meta AI	Meta AI

Conclusion 🏁

A missing return statement breaks your code’s flow and produces unreliable results.

Always ensure every branch in your function returns something meaningful.

Relations 👩‍❤️‍💋‍👨

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xv

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxi

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxiii

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxiv

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxviii

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-viii-8mn3352

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii

Disclaimer 📘

Code Smells are my opinion.

Credits 🙏

Photo by Tim Johnson on Unsplash

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A bug is never just a mistake. It represents something bigger.

Sergey Zefirov

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This article is part of the CodeSmell Series.