rust/tests/ui/transmute.rs

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// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
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#![allow(dead_code)]
extern crate core;
use std::mem::transmute as my_transmute;
use std::vec::Vec as MyVec;
fn my_int() -> Usize {
Usize(42)
}
fn my_vec() -> MyVec<i32> {
vec![]
}
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#[allow(clippy::needless_lifetimes, clippy::transmute_ptr_to_ptr)]
#[warn(clippy::useless_transmute)]
unsafe fn _generic<'a, T, U: 'a>(t: &'a T) {
let _: &'a T = core::intrinsics::transmute(t);
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let _: &'a U = core::intrinsics::transmute(t);
let _: *const T = core::intrinsics::transmute(t);
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let _: *mut T = core::intrinsics::transmute(t);
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let _: *const U = core::intrinsics::transmute(t);
}
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#[warn(clippy::transmute_ptr_to_ref)]
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unsafe fn _ptr_to_ref<T, U>(p: *const T, m: *mut T, o: *const U, om: *mut U) {
let _: &T = std::mem::transmute(p);
let _: &T = &*p;
let _: &mut T = std::mem::transmute(m);
let _: &mut T = &mut *m;
let _: &T = std::mem::transmute(m);
let _: &T = &*m;
let _: &mut T = std::mem::transmute(p as *mut T);
let _ = &mut *(p as *mut T);
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let _: &T = std::mem::transmute(o);
let _: &T = &*(o as *const T);
let _: &mut T = std::mem::transmute(om);
let _: &mut T = &mut *(om as *mut T);
let _: &T = std::mem::transmute(om);
let _: &T = &*(om as *const T);
}
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#[warn(clippy::transmute_ptr_to_ref)]
fn issue1231() {
struct Foo<'a, T: 'a> {
bar: &'a T,
}
let raw = 42 as *const i32;
let _: &Foo<u8> = unsafe { std::mem::transmute::<_, &Foo<_>>(raw) };
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let _: &Foo<&u8> = unsafe { std::mem::transmute::<_, &Foo<&_>>(raw) };
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type Bar<'a> = &'a u8;
let raw = 42 as *const i32;
unsafe { std::mem::transmute::<_, Bar>(raw) };
}
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#[warn(clippy::useless_transmute)]
fn useless() {
unsafe {
let _: Vec<i32> = core::intrinsics::transmute(my_vec());
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let _: Vec<i32> = core::mem::transmute(my_vec());
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let _: Vec<i32> = std::intrinsics::transmute(my_vec());
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let _: Vec<i32> = std::mem::transmute(my_vec());
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let _: Vec<i32> = my_transmute(my_vec());
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let _: Vec<u32> = core::intrinsics::transmute(my_vec());
let _: Vec<u32> = core::mem::transmute(my_vec());
let _: Vec<u32> = std::intrinsics::transmute(my_vec());
let _: Vec<u32> = std::mem::transmute(my_vec());
let _: Vec<u32> = my_transmute(my_vec());
let _: *const usize = std::mem::transmute(5_isize);
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let _ = 5_isize as *const usize;
let _: *const usize = std::mem::transmute(1+1usize);
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let _ = (1+1_usize) as *const usize;
}
}
struct Usize(usize);
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#[warn(clippy::crosspointer_transmute)]
fn crosspointer() {
let mut int: Usize = Usize(0);
let int_const_ptr: *const Usize = &int as *const Usize;
let int_mut_ptr: *mut Usize = &mut int as *mut Usize;
unsafe {
let _: Usize = core::intrinsics::transmute(int_const_ptr);
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let _: Usize = core::intrinsics::transmute(int_mut_ptr);
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let _: *const Usize = core::intrinsics::transmute(my_int());
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let _: *mut Usize = core::intrinsics::transmute(my_int());
}
}
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#[warn(clippy::transmute_int_to_char)]
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fn int_to_char() {
let _: char = unsafe { std::mem::transmute(0_u32) };
let _: char = unsafe { std::mem::transmute(0_i32) };
}
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#[warn(clippy::transmute_int_to_bool)]
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fn int_to_bool() {
let _: bool = unsafe { std::mem::transmute(0_u8) };
}
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#[warn(clippy::transmute_int_to_float)]
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fn int_to_float() {
let _: f32 = unsafe { std::mem::transmute(0_u32) };
let _: f32 = unsafe { std::mem::transmute(0_i32) };
}
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fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
let _: &str = unsafe { std::mem::transmute(b) };
let _: &mut str = unsafe { std::mem::transmute(mb) };
}
// Make sure we can modify lifetimes, which is one of the recommended uses
// of transmute
// Make sure we can do static lifetime transmutes
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#[warn(clippy::transmute_ptr_to_ptr)]
unsafe fn transmute_lifetime_to_static<'a, T>(t: &'a T) -> &'static T {
std::mem::transmute::<&'a T, &'static T>(t)
}
// Make sure we can do non-static lifetime transmutes
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#[warn(clippy::transmute_ptr_to_ptr)]
unsafe fn transmute_lifetime<'a, 'b, T>(t: &'a T, u: &'b T) -> &'b T {
std::mem::transmute::<&'a T, &'b T>(t)
}
struct LifetimeParam<'a> {
s: &'a str,
}
struct GenericParam<T> {
t: T,
}
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#[warn(clippy::transmute_ptr_to_ptr)]
fn transmute_ptr_to_ptr() {
let ptr = &1u32 as *const u32;
let mut_ptr = &mut 1u32 as *mut u32;
unsafe {
// pointer-to-pointer transmutes; bad
let _: *const f32 = std::mem::transmute(ptr);
let _: *mut f32 = std::mem::transmute(mut_ptr);
// ref-ref transmutes; bad
let _: &f32 = std::mem::transmute(&1u32);
let _: &f64 = std::mem::transmute(&1f32);
// ^ this test is here because both f32 and f64 are the same TypeVariant, but they are not
// the same type
let _: &mut f32 = std::mem::transmute(&mut 1u32);
let _: &GenericParam<f32> = std::mem::transmute(&GenericParam { t: 1u32 });
}
// these are recommendations for solving the above; if these lint we need to update
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// those suggestions
let _ = ptr as *const f32;
let _ = mut_ptr as *mut f32;
let _ = unsafe { &*(&1u32 as *const u32 as *const f32) };
let _ = unsafe { &mut *(&mut 1u32 as *mut u32 as *mut f32) };
// transmute internal lifetimes, should not lint
let s = "hello world".to_owned();
let lp = LifetimeParam { s: &s };
let _: &LifetimeParam<'static> = unsafe { std::mem::transmute(&lp) };
let _: &GenericParam<&LifetimeParam<'static>> = unsafe {
std::mem::transmute(&GenericParam { t: &lp})
};
}
fn main() { }