Identify and resolve common Rust code anti-patterns during review.
Works with
Covers eight major anti-patterns with explanations and idiomatic alternatives, including excessive cloning, unwrap in production, and fighting the borrow checker
Provides a thinking framework to distinguish symptoms from root causes and trace issues to underlying design problems
Includes quick reference tables for beginner mistakes, code smells, common error patterns, and deprecated approaches with fixes
Links anti
AI-first code editor with Composer
Before installing skills in Cursor, ensure your development environment meets these requirements:
node --versionm15-anti-patternExecute the skills CLI command in your project's root directory to begin installation:
Fetches m15-anti-pattern from zhanghandong/rust-skills and configures it for Cursor.
The CLI shows a list of agents. Use arrow keys and space to select Cursor:
Confirm successful installation by checking the skill directory location:
Restart Cursor to activate m15-anti-pattern. Access via /m15-anti-pattern in your agent's command palette.
We perform automated surface-level scans (Gen AI Scanner, Socket, Snyk) during installation. These checks detect common vulnerabilities but do not guarantee complete security. Always review skill source code and verify the publisher's reputation before production use.
Skills execute code in your environment. Always review source, verify the publisher, and test in isolation before production.
Submit your Claude Code skill and start earning
Create detailed user stories, acceptance criteria, and feature specs
Example
Generate user stories for 'password reset feature' with acceptance criteria, edge cases, and test scenarios
Reduce spec writing time by 50%, ensure comprehensive coverage
Research competitors, compare features, identify gaps
Example
Analyze 5 competitor products, create feature comparison matrix, suggest differentiation opportunities
Complete competitive research in 2 hours instead of 2 days
Evaluate features using frameworks (RICE, ICE, Kano) and create prioritized backlogs
Example
Score 20 feature ideas using RICE framework, generate prioritized roadmap with rationale
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Layer 2: Design Choices
Is this pattern hiding a design problem?
When reviewing code:
| Anti-Pattern | Why Bad | Better |
|---|---|---|
.clone() everywhere |
Hides ownership issues | Proper references or ownership |
.unwrap() in production |
Runtime panics | ?, expect, or handling |
Rc when single owner |
Unnecessary overhead | Simple ownership |
unsafe for convenience |
UB risk | Find safe pattern |
OOP via Deref |
Misleading API | Composition, traits |
| Giant match arms | Unmaintainable | Extract to methods |
String everywhere |
Allocation waste | &str, Cow<str> |
Ignoring #[must_use] |
Lost errors | Handle or let _ = |
When seeing suspicious code:
Is this symptom or cause?
What would idiomatic code look like?
Does this fight Rust?
To design understanding:
"Why does my code have so many clones?"
↑ Ask: Is the ownership model correct?
↑ Check: m09-domain (data flow design)
↑ Check: m01-ownership (reference patterns)
| Anti-Pattern | Trace To | Question |
|---|---|---|
| Clone everywhere | m01-ownership | Who should own this data? |
| Unwrap everywhere | m06-error-handling | What's the error strategy? |
| Rc everywhere | m09-domain | Is ownership clear? |
| Fighting lifetimes | m09-domain | Should data structure change? |
To implementation (Layer 1):
"Replace clone with proper ownership"
↓ m01-ownership: Reference patterns
↓ m02-resource: Smart pointer if needed
"Replace unwrap with proper handling"
↓ m06-error-handling: ? operator
↓ m06-error-handling: expect with message
| Rank | Mistake | Fix |
|---|---|---|
| 1 | Clone to escape borrow checker | Use references |
| 2 | Unwrap in production | Propagate with ? |
| 3 | String for everything | Use &str |
| 4 | Index loops | Use iterators |
| 5 | Fighting lifetimes | Restructure to own data |
| Smell | Indicates | Refactoring |
|---|---|---|
Many .clone() |
Ownership unclear | Clarify data flow |
Many .unwrap() |
Error handling missing | Add proper handling |
Many pub fields |
Encapsulation broken | Private + accessors |
| Deep nesting | Complex logic | Extract methods |
| Long functions | Multiple responsibilities | Split |
| Giant enums | Missing abstraction | Trait + types |
| Error | Anti-Pattern Cause | Fix |
|---|---|---|
| E0382 use after move | Cloning vs ownership | Proper references |
| Panic in production | Unwrap everywhere | ?, matching |
| Slow performance | String for all text | &str, Cow |
| Borrow checker fights | Wrong structure | Restructure |
| Memory bloat | Rc/Arc everywhere | Simple ownership |
| Deprecated | Better |
|---|---|
| Index-based loops | .iter(), .enumerate() |
collect::<Vec<_>>() then iterate |
Chain iterators |
| Manual unsafe cell | Cell, RefCell |
mem::transmute for casts |
as or TryFrom |
| Custom linked list | Vec, VecDeque |
lazy_static! |
std::sync::OnceLock |
.clone() without justification.unwrap() in library codepub fields with invariantsString where &str suffices#[must_use] warningsunsafe without SAFETY comment| When | See |
|---|---|
| Ownership patterns | m01-ownership |
| Error handling | m06-error-handling |
| Mental models | m14-mental-model |
| Performance | m10-performance |
Make data-driven prioritization decisions faster
Draft PRDs, status updates, and stakeholder presentations
Example
Create executive summary of Q3 roadmap, monthly progress report, feature launch announcement
Save 3-5 hours/week on communication overhead
Prerequisites
Time Estimate
30-60 minutes to see productivity improvements
Steps
Common Pitfalls
✓ Do
✗ Don't
💡 Pro Tips
✓ Use when
Use for user story writing, competitive research, roadmap prioritization, stakeholder communication, and PRD drafting. Best for reducing repetitive documentation and research work.
✗ Avoid when
Avoid for strategic product vision (requires deep customer empathy), pricing decisions (needs market and financial expertise), or when face-to-face customer discovery is more valuable than speed.
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m15-anti-pattern is among the better-maintained entries we tried; worth keeping pinned for repeat workflows.
We added m15-anti-pattern from the explainx registry; install was straightforward and the SKILL.md answered most questions upfront.
Useful defaults in m15-anti-pattern — fewer surprises than typical one-off scripts, and it plays nicely with `npx skills` flows.
I recommend m15-anti-pattern for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
I recommend m15-anti-pattern for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
Useful defaults in m15-anti-pattern — fewer surprises than typical one-off scripts, and it plays nicely with `npx skills` flows.
We added m15-anti-pattern from the explainx registry; install was straightforward and the SKILL.md answered most questions upfront.
Keeps context tight: m15-anti-pattern is the kind of skill you can hand to a new teammate without a long onboarding doc.
m15-anti-pattern has been reliable in day-to-day use. Documentation quality is above average for community skills.
Solid pick for teams standardizing on skills: m15-anti-pattern is focused, and the summary matches what you get after install.
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