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go.slice_memory_leak

Performance Medium

Detects slice operations that retain references to underlying arrays, causing memory leaks.

Why It Matters

Slice memory leaks cause:

Hidden memory retention — Small slice keeps large array alive
Gradual memory growth — Leaks accumulate over time
Hard to diagnose — Memory profiler shows slices, not retained arrays

Example

// ❌ Before (retains entire array)
func getPrefix(data []byte) []byte {
    return data[:10] // Keeps entire backing array!
}

// ✅ After (copies to new slice)
func getPrefix(data []byte) []byte {
    prefix := make([]byte, 10)
    copy(prefix, data[:10])
    return prefix // Only 10 bytes retained
}

What Unfault Detects

Returning slice of large input
Storing sub-slices in long-lived structures
Appending without copying when source is discarded

Auto-Fix

Unfault generates copy patterns:

result := make([]T, len(subslice))
copy(result, subslice)