5 use std::mem::transmute as my_transmute;
6 use std::vec::Vec as MyVec;
12 fn my_vec() -> MyVec<i32> {
16 #[allow(clippy::needless_lifetimes, clippy::transmute_ptr_to_ptr)]
17 #[warn(clippy::useless_transmute)]
18 unsafe fn _generic<'a, T, U: 'a>(t: &'a T) {
19 let _: &'a T = core::intrinsics::transmute(t);
21 let _: &'a U = core::intrinsics::transmute(t);
23 let _: *const T = core::intrinsics::transmute(t);
25 let _: *mut T = core::intrinsics::transmute(t);
27 let _: *const U = core::intrinsics::transmute(t);
30 #[warn(clippy::transmute_ptr_to_ref)]
31 unsafe fn _ptr_to_ref<T, U>(p: *const T, m: *mut T, o: *const U, om: *mut U) {
32 let _: &T = std::mem::transmute(p);
35 let _: &mut T = std::mem::transmute(m);
36 let _: &mut T = &mut *m;
38 let _: &T = std::mem::transmute(m);
41 let _: &mut T = std::mem::transmute(p as *mut T);
42 let _ = &mut *(p as *mut T);
44 let _: &T = std::mem::transmute(o);
45 let _: &T = &*(o as *const T);
47 let _: &mut T = std::mem::transmute(om);
48 let _: &mut T = &mut *(om as *mut T);
50 let _: &T = std::mem::transmute(om);
51 let _: &T = &*(om as *const T);
54 #[warn(clippy::transmute_ptr_to_ref)]
56 struct Foo<'a, T: 'a> {
60 let raw = 42 as *const i32;
61 let _: &Foo<u8> = unsafe { std::mem::transmute::<_, &Foo<_>>(raw) };
63 let _: &Foo<&u8> = unsafe { std::mem::transmute::<_, &Foo<&_>>(raw) };
65 type Bar<'a> = &'a u8;
66 let raw = 42 as *const i32;
67 unsafe { std::mem::transmute::<_, Bar>(raw) };
70 #[warn(clippy::useless_transmute)]
73 let _: Vec<i32> = core::intrinsics::transmute(my_vec());
75 let _: Vec<i32> = core::mem::transmute(my_vec());
77 let _: Vec<i32> = std::intrinsics::transmute(my_vec());
79 let _: Vec<i32> = std::mem::transmute(my_vec());
81 let _: Vec<i32> = my_transmute(my_vec());
83 let _: Vec<u32> = core::intrinsics::transmute(my_vec());
84 let _: Vec<u32> = core::mem::transmute(my_vec());
85 let _: Vec<u32> = std::intrinsics::transmute(my_vec());
86 let _: Vec<u32> = std::mem::transmute(my_vec());
87 let _: Vec<u32> = my_transmute(my_vec());
89 let _: *const usize = std::mem::transmute(5_isize);
91 let _ = 5_isize as *const usize;
93 let _: *const usize = std::mem::transmute(1 + 1usize);
95 let _ = (1 + 1_usize) as *const usize;
101 #[warn(clippy::crosspointer_transmute)]
103 let mut int: Usize = Usize(0);
104 let int_const_ptr: *const Usize = &int as *const Usize;
105 let int_mut_ptr: *mut Usize = &mut int as *mut Usize;
108 let _: Usize = core::intrinsics::transmute(int_const_ptr);
110 let _: Usize = core::intrinsics::transmute(int_mut_ptr);
112 let _: *const Usize = core::intrinsics::transmute(my_int());
114 let _: *mut Usize = core::intrinsics::transmute(my_int());
118 #[warn(clippy::transmute_int_to_char)]
120 let _: char = unsafe { std::mem::transmute(0_u32) };
121 let _: char = unsafe { std::mem::transmute(0_i32) };
124 #[warn(clippy::transmute_int_to_bool)]
126 let _: bool = unsafe { std::mem::transmute(0_u8) };
129 #[warn(clippy::transmute_int_to_float)]
131 let _: f32 = unsafe { std::mem::transmute(0_u32) };
132 let _: f32 = unsafe { std::mem::transmute(0_i32) };
135 fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
136 let _: &str = unsafe { std::mem::transmute(b) };
137 let _: &mut str = unsafe { std::mem::transmute(mb) };
140 // Make sure we can modify lifetimes, which is one of the recommended uses
143 // Make sure we can do static lifetime transmutes
144 #[warn(clippy::transmute_ptr_to_ptr)]
145 unsafe fn transmute_lifetime_to_static<'a, T>(t: &'a T) -> &'static T {
146 std::mem::transmute::<&'a T, &'static T>(t)
149 // Make sure we can do non-static lifetime transmutes
150 #[warn(clippy::transmute_ptr_to_ptr)]
151 unsafe fn transmute_lifetime<'a, 'b, T>(t: &'a T, u: &'b T) -> &'b T {
152 std::mem::transmute::<&'a T, &'b T>(t)
155 struct LifetimeParam<'a> {
159 struct GenericParam<T> {
163 #[warn(clippy::transmute_ptr_to_ptr)]
164 fn transmute_ptr_to_ptr() {
165 let ptr = &1u32 as *const u32;
166 let mut_ptr = &mut 1u32 as *mut u32;
168 // pointer-to-pointer transmutes; bad
169 let _: *const f32 = std::mem::transmute(ptr);
170 let _: *mut f32 = std::mem::transmute(mut_ptr);
171 // ref-ref transmutes; bad
172 let _: &f32 = std::mem::transmute(&1u32);
173 let _: &f64 = std::mem::transmute(&1f32);
174 // ^ this test is here because both f32 and f64 are the same TypeVariant, but they are not
176 let _: &mut f32 = std::mem::transmute(&mut 1u32);
177 let _: &GenericParam<f32> = std::mem::transmute(&GenericParam { t: 1u32 });
180 // these are recommendations for solving the above; if these lint we need to update
182 let _ = ptr as *const f32;
183 let _ = mut_ptr as *mut f32;
184 let _ = unsafe { &*(&1u32 as *const u32 as *const f32) };
185 let _ = unsafe { &mut *(&mut 1u32 as *mut u32 as *mut f32) };
187 // transmute internal lifetimes, should not lint
188 let s = "hello world".to_owned();
189 let lp = LifetimeParam { s: &s };
190 let _: &LifetimeParam<'static> = unsafe { std::mem::transmute(&lp) };
191 let _: &GenericParam<&LifetimeParam<'static>> = unsafe { std::mem::transmute(&GenericParam { t: &lp }) };