go runtime_error ai_generated true

panic: runtime error: slice bounds out of range [:5] with capacity 3

ID: go/panic-runtime-error-slice-bounds-out-of-range-capacity

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92%Fix Rate

88%Confidence

1Evidence

2023-03-15First Seen

Version Compatibility

Version	Status	Introduced	Deprecated	Notes
go1.20	active	—	—	—
go1.21	active	—	—	—
go1.22	active	—	—	—

Attempting to slice a slice or array beyond its capacity, e.g., s[:5] when cap(s) is only 3.

generic

尝试对切片或数组进行超出其容量的切片操作，例如当 cap(s) 仅为 3 时执行 s[:5]。

95% success Check the capacity before slicing: if cap(s) < 5 { s = append(s, make([]T, 5-cap(s))...) }; result := s[:5]
```
Check the capacity before slicing: if cap(s) < 5 { s = append(s, make([]T, 5-cap(s))...) }; result := s[:5]
```
93% success Use copy() to create a new slice with sufficient capacity: dst := make([]T, 5); copy(dst, s)
```
Use copy() to create a new slice with sufficient capacity: dst := make([]T, 5); copy(dst, s)
```
90% success Ensure the slice is initialized with sufficient capacity from the start: s := make([]T, 0, 5); s = append(s, ...)
```
Ensure the slice is initialized with sufficient capacity from the start: s := make([]T, 0, 5); s = append(s, ...)
```

在切片前检查容量：if cap(s) < 5 { s = append(s, make([]T, 5-cap(s))...) }; result := s[:5]

使用 copy() 创建一个具有足够容量的新切片：dst := make([]T, 5); copy(dst, s)

确保从一开始就用足够的容量初始化切片：s := make([]T, 0, 5); s = append(s, ...)

Common approaches that don't work:

Change the slice bounds to a smaller number without checking capacity 70% fail
Arbitrary reduction may hide the real bug or cause data loss
Ignore the panic and rely on recover() in production 90% fail
Recovering from a bounds panic is unsafe and may leave state inconsistent
Use append() to extend the slice before slicing 60% fail
append() may reallocate, but doesn't fix the root cause of accessing beyond capacity