src/tools/clippy/tests/ui/transmute.rs

   1
   2
   3
   4 #![allow(dead_code)]
   5
   6 extern crate core;
   7
   8 use std::mem::transmute as my_transmute;
   9 use std::vec::Vec as MyVec;
  10
  11 fn my_int() -> Usize {
  12     Usize(42)
  13 }
  14
  15 fn my_vec() -> MyVec<i32> {
  16     vec![]
  17 }
  18
  19 #[allow(needless_lifetimes, transmute_ptr_to_ptr)]
  20 #[warn(useless_transmute)]
  21 unsafe fn _generic<'a, T, U: 'a>(t: &'a T) {
  22     let _: &'a T = core::intrinsics::transmute(t);
  23
  24     let _: &'a U = core::intrinsics::transmute(t);
  25
  26     let _: *const T = core::intrinsics::transmute(t);
  27
  28     let _: *mut T = core::intrinsics::transmute(t);
  29
  30     let _: *const U = core::intrinsics::transmute(t);
  31 }
  32
  33 #[warn(transmute_ptr_to_ref)]
  34 unsafe fn _ptr_to_ref<T, U>(p: *const T, m: *mut T, o: *const U, om: *mut U) {
  35     let _: &T = std::mem::transmute(p);
  36     let _: &T = &*p;
  37
  38     let _: &mut T = std::mem::transmute(m);
  39     let _: &mut T = &mut *m;
  40
  41     let _: &T = std::mem::transmute(m);
  42     let _: &T = &*m;
  43
  44     let _: &mut T = std::mem::transmute(p as *mut T);
  45     let _ = &mut *(p as *mut T);
  46
  47     let _: &T = std::mem::transmute(o);
  48     let _: &T = &*(o as *const T);
  49
  50     let _: &mut T = std::mem::transmute(om);
  51     let _: &mut T = &mut *(om as *mut T);
  52
  53     let _: &T = std::mem::transmute(om);
  54     let _: &T = &*(om as *const T);
  55 }
  56
  57 #[warn(transmute_ptr_to_ref)]
  58 fn issue1231() {
  59     struct Foo<'a, T: 'a> {
  60         bar: &'a T,
  61     }
  62
  63     let raw = 42 as *const i32;
  64     let _: &Foo<u8> = unsafe { std::mem::transmute::<_, &Foo<_>>(raw) };
  65
  66     let _: &Foo<&u8> = unsafe { std::mem::transmute::<_, &Foo<&_>>(raw) };
  67
  68     type Bar<'a> = &'a u8;
  69     let raw = 42 as *const i32;
  70     unsafe { std::mem::transmute::<_, Bar>(raw) };
  71 }
  72
  73 #[warn(useless_transmute)]
  74 fn useless() {
  75     unsafe {
  76         let _: Vec<i32> = core::intrinsics::transmute(my_vec());
  77
  78         let _: Vec<i32> = core::mem::transmute(my_vec());
  79
  80         let _: Vec<i32> = std::intrinsics::transmute(my_vec());
  81
  82         let _: Vec<i32> = std::mem::transmute(my_vec());
  83
  84         let _: Vec<i32> = my_transmute(my_vec());
  85
  86         let _: Vec<u32> = core::intrinsics::transmute(my_vec());
  87         let _: Vec<u32> = core::mem::transmute(my_vec());
  88         let _: Vec<u32> = std::intrinsics::transmute(my_vec());
  89         let _: Vec<u32> = std::mem::transmute(my_vec());
  90         let _: Vec<u32> = my_transmute(my_vec());
  91
  92         let _: *const usize = std::mem::transmute(5_isize);
  93
  94         let _  = 5_isize as *const usize;
  95
  96         let _: *const usize = std::mem::transmute(1+1usize);
  97
  98         let _  = (1+1_usize) as *const usize;
  99     }
 100 }
 101
 102 struct Usize(usize);
 103
 104 #[warn(crosspointer_transmute)]
 105 fn crosspointer() {
 106     let mut int: Usize = Usize(0);
 107     let int_const_ptr: *const Usize = &int as *const Usize;
 108     let int_mut_ptr: *mut Usize = &mut int as *mut Usize;
 109
 110     unsafe {
 111         let _: Usize = core::intrinsics::transmute(int_const_ptr);
 112
 113         let _: Usize = core::intrinsics::transmute(int_mut_ptr);
 114
 115         let _: *const Usize = core::intrinsics::transmute(my_int());
 116
 117         let _: *mut Usize = core::intrinsics::transmute(my_int());
 118     }
 119 }
 120
 121 #[warn(transmute_int_to_char)]
 122 fn int_to_char() {
 123     let _: char = unsafe { std::mem::transmute(0_u32) };
 124     let _: char = unsafe { std::mem::transmute(0_i32) };
 125 }
 126
 127 #[warn(transmute_int_to_bool)]
 128 fn int_to_bool() {
 129     let _: bool = unsafe { std::mem::transmute(0_u8) };
 130 }
 131
 132 #[warn(transmute_int_to_float)]
 133 fn int_to_float() {
 134     let _: f32 = unsafe { std::mem::transmute(0_u32) };
 135     let _: f32 = unsafe { std::mem::transmute(0_i32) };
 136 }
 137
 138 fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
 139     let _: &str = unsafe { std::mem::transmute(b) };
 140     let _: &mut str = unsafe { std::mem::transmute(mb) };
 141 }
 142
 143 #[warn(transmute_ptr_to_ptr)]
 144 fn transmute_ptr_to_ptr() {
 145     let ptr = &1u32 as *const u32;
 146     let mut_ptr = &mut 1u32 as *mut u32;
 147     unsafe {
 148         // pointer-to-pointer transmutes; bad
 149         let _: *const f32 = std::mem::transmute(ptr);
 150         let _: *mut f32 = std::mem::transmute(mut_ptr);
 151         // ref-ref transmutes; bad
 152         let _: &f32 = std::mem::transmute(&1u32);
 153         let _: &mut f32 = std::mem::transmute(&mut 1u32);
 154     }
 155     // These should be fine
 156     let _ = ptr as *const f32;
 157     let _ = mut_ptr as *mut f32;
 158     let _ = unsafe { &*(&1u32 as *const u32 as *const f32) };
 159     let _ = unsafe { &mut *(&mut 1u32 as *mut u32 as *mut f32) };
 160 }
 161
 162 fn main() { }