Contents
V8031. Using the call of the 'len' function as an index will result in an off-by-one error.
The analyzer has detected a potential off-by-one error caused by using the result of the len function as an index. Such an error causes the program to panic.
The code example:
func End(basicLits []*BasicLit) token.Pos {
return basicLits[len(basicLits)].End()
}Developers wanted to obtain the last element position of the basicLits slice. However, for a n-length slice, valid indices range from 0 to n - 1, so accessing basicLits[len(basicLits)] always results in the program panic.
Fixed code:
func End(basicLits []*BasicLit) token.Pos {
if length := len(basicLits); length > 0 {
return basicLits[length - 1].End()
}
return token.NoPos
}If a function has a precondition of working with non-zero length slices, then the length > 0 check can be removed.
Was this page helpful?
