| name | mojo-memory-check |
| description | Verify memory safety in Mojo code including ownership, borrowing, and lifetime management. Use when reviewing code or debugging memory issues. |
| mcp_fallback | none |
| category | mojo |
Memory Safety Check Skill
Validate Mojo ownership and borrowing rules.
When to Use
- Reviewing code for memory safety
- Debugging memory or segfault issues
- Before merging code
- Performance testing reveals corruption
Quick Reference
# Owned parameter - takes ownership
fn consume(var data: Tensor):
process(data) # data moved here
# Borrowed parameter - read-only reference
fn read_only(data: Tensor):
let value = data[0] # OK: read-only
# Mutable reference - in-place modification
fn modify(mut data: Tensor):
data[0] = 42 # Mutate in caller's variable
Workflow
- Trace ownership - Which function owns each value
- Check borrows - Are references short-lived
- Verify moves - Use
^ operator for ownership transfer
- Test lifetimes - Compile and run with memory checks
- Debug issues - Identify use-after-move or dangling refs
Mojo-Specific Notes
- Use
^ operator ONLY when transferring ownership
mut self for mutating methods (NOT out self)out self ONLY for constructors (__init__)- List/Dict/String are non-copyable - must use
^ when returning
Error Handling
| Error |
Cause |
Solution |
Use after move |
Variable used after ownership transfer |
Create copy or don't move |
Dangling reference |
Reference to local variable |
Return owned value with ^ |
Mutable aliasing |
Multiple mutable refs to same data |
Ensure single mutable reference |
Type not copyable |
Missing ^ on non-copyable return |
Add transfer operator ^ |
References
.claude/shared/mojo-anti-patterns.md - Ownership violations section.claude/shared/mojo-guidelines.md - Parameter conventions table