Pointer returned from a function is dereferenced on LHS of an assignement CXX-W1230
Anti-pattern
Minor
When a function returns a pointer to dynamically allocated memory, it is the responsibility of the caller to free that memory after it is no longer needed. But if the caller deferences such a pointer on the left-hand side of an assignment expression, the caller loses the oppurtunity to free the memory.
To avoid this issue, it is recommended to store the returned pointer in a temporary variable, use it as needed, and then free the memory before exiting the caller function.
Bad practice
int* ret(int* num) {
return num;
}
int* ret_leak() {
return (int*)malloc(sizeof(int));
}
int main() {
int t = 10;
*ret(&t) = 20;
// We forget the returned pointer here,
// which may leak memory.
*ret_leak() = 20;
printf("%d", t);
}
Recommended
int* ret(int* num) {
return num;
}
int* ret_leak() {
return (int*)malloc(sizeof(int));
}
int main() {
int t = 10;
*ret(&t) = 20;
int* rl = ret_leak();
// The pointer be stored in a local variable,
// allowing us to free or reuse it if needed.
*rl = 20;
printf("%d", t);
printf("%d", *rl);
}