rust-clippy/tests/ui/uninit_vec.rs

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#![warn(clippy::uninit_vec)]
use std::mem::MaybeUninit;
#[derive(Default)]
struct MyVec {
vec: Vec<u8>,
}
fn main() {
// with_capacity() -> set_len() should be detected
let mut vec: Vec<u8> = Vec::with_capacity(1000);
unsafe {
vec.set_len(200);
}
// reserve() -> set_len() should be detected
vec.reserve(1000);
unsafe {
vec.set_len(200);
}
// new() -> set_len() should be detected
let mut vec: Vec<u8> = Vec::new();
unsafe {
vec.set_len(200);
}
// default() -> set_len() should be detected
let mut vec: Vec<u8> = Default::default();
unsafe {
vec.set_len(200);
}
let mut vec: Vec<u8> = Vec::default();
unsafe {
vec.set_len(200);
}
// test when both calls are enclosed in the same unsafe block
unsafe {
let mut vec: Vec<u8> = Vec::with_capacity(1000);
vec.set_len(200);
vec.reserve(1000);
vec.set_len(200);
}
let mut vec: Vec<u8> = Vec::with_capacity(1000);
unsafe {
// test the case where there are other statements in the following unsafe block
vec.set_len(200);
assert!(vec.len() == 200);
}
// handle vec stored in the field of a struct
let mut my_vec = MyVec::default();
my_vec.vec.reserve(1000);
unsafe {
my_vec.vec.set_len(200);
}
my_vec.vec = Vec::with_capacity(1000);
unsafe {
my_vec.vec.set_len(200);
}
// Test `#[allow(...)]` attributes on inner unsafe block (shouldn't trigger)
let mut vec: Vec<u8> = Vec::with_capacity(1000);
#[allow(clippy::uninit_vec)]
unsafe {
vec.set_len(200);
}
// MaybeUninit-wrapped types should not be detected
unsafe {
let mut vec: Vec<MaybeUninit<u8>> = Vec::with_capacity(1000);
vec.set_len(200);
let mut vec: Vec<(MaybeUninit<u8>, MaybeUninit<bool>)> = Vec::with_capacity(1000);
vec.set_len(200);
let mut vec: Vec<(MaybeUninit<u8>, [MaybeUninit<bool>; 2])> = Vec::with_capacity(1000);
vec.set_len(200);
}
// known false negative
let mut vec1: Vec<u8> = Vec::with_capacity(1000);
let mut vec2: Vec<u8> = Vec::with_capacity(1000);
unsafe {
vec1.set_len(200);
vec2.set_len(200);
}
// set_len(0) should not be detected
let mut vec: Vec<u8> = Vec::with_capacity(1000);
unsafe {
vec.set_len(0);
}
}