pi-lens/rules/tree-sitter-queries/rust/rust-clone-in-loop.yml

Real-time code feedback for pi — LSP, linters, formatters, type-checking, structural analysis & booboo

# Rust Clone in Loop
# Detects unnecessary clone() calls in hot loops
id: rust-clone-in-loop
name: Clone in Hot Loop
severity: info
category: performance
defect_class: safety
inline_tier: warning
language: rust

message: "clone() in loop may hurt performance — consider borrowing or moving"

description: |
  Cloning values in a loop can be expensive, especially for large types.
  Consider using references (&T) instead of owned values.
  
  ✅ FIX: Use &T instead of cloning, or restructure to move values.

query: |
  (for_expression
    body: (block
      (call_expression
        function: (field_expression
          field: (field_identifier) @METHOD)
        (#eq? @METHOD "clone")) @CALL))

metavars:
  - METHOD
  - CALL

has_fix: false

tags:
  - rust
  - performance
  - memory

examples:
  bad: |
    for item in &items {
        process(item.clone());  // Unnecessary clone
    }
  
  good: |
    for item in &items {
        process(item);  // Borrow instead
    }
    // Or if process needs ownership:
    for item in items {  // Move items
        process(item);
    }