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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs')
-rw-r--r-- | src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs b/src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs new file mode 100644 index 000000000..f06ffab5d --- /dev/null +++ b/src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs @@ -0,0 +1,63 @@ +#![warn(clippy::transmute_ptr_to_ptr)] +#![allow(clippy::borrow_as_ptr)] + +// Make sure we can modify lifetimes, which is one of the recommended uses +// of transmute + +// Make sure we can do static lifetime transmutes +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 +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, +} + +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 + // 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 }) }; +} + +// dereferencing raw pointers in const contexts, should not lint as it's unstable (issue 5959) +const _: &() = { + struct Zst; + let zst = &Zst; + + unsafe { std::mem::transmute::<&'static Zst, &'static ()>(zst) } +}; + +fn main() {} |