Memory Safety Check Skill

Name: mojo-memory-check
Rating: 92
Author: HomericIntelligence

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

mojo

# 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