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Warn on references casting to bigger memory layout #118983

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merged 4 commits into from
Feb 13, 2024
Merged

Warn on references casting to bigger memory layout #118983

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915200f
Lint on reference casting to bigger underlying allocation
Urgau Dec 13, 2023
6a8f50e
Introduce small cache to avoid recomputing the same value twice
Urgau Dec 15, 2023
746bb7e
Avoid UB in clippy transmute_ptr_to_ptr UI test
Urgau Dec 17, 2023
e08c9d1
Allow invalid ref casting in Miri unaligned_ref_addr_of test
Urgau Dec 17, 2023
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Avoid UB in clippy transmute_ptr_to_ptr UI test
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@Urgau
Urgau committed Feb 12, 2024
commit 746bb7e13610df9a9f88222a74302b93456c1675
6 changes: 3 additions & 3 deletions src/tools/clippy/tests/ui/transmute_ptr_to_ptr.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -35,16 35,16 @@ fn transmute_ptr_to_ptr() {
// ref-ref transmutes; bad
let _: &f32 = &*(&1u32 as *const u32 as *const f32);
//~^ ERROR: transmute from a reference to a reference
let _: &f64 = &*(&1f32 as *const f32 as *const f64);
let _: &f32 = &*(&1f64 as *const f64 as *const f32);
//~^ ERROR: transmute from a reference to a reference
//:^ this test is here because both f32 and f64 are the same TypeVariant, but they are not
// the same type
let _: &mut f32 = &mut *(&mut 1u32 as *mut u32 as *mut f32);
//~^ ERROR: transmute from a reference to a reference
let _: &GenericParam<f32> = &*(&GenericParam { t: 1u32 } as *const GenericParam<u32> as *const GenericParam<f32>);
//~^ ERROR: transmute from a reference to a reference
let u8_ref: &u8 = &0u8;
let u64_ref: &u64 = unsafe { &*(u8_ref as *const u8 as *const u64) };
let u64_ref: &u64 = &0u64;
let u8_ref: &u8 = unsafe { &*(u64_ref as *const u64 as *const u8) };
//~^ ERROR: transmute from a reference to a reference
}

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6 changes: 3 additions & 3 deletions src/tools/clippy/tests/ui/transmute_ptr_to_ptr.rs
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Expand Up @@ -35,16 35,16 @@ fn transmute_ptr_to_ptr() {
// ref-ref transmutes; bad
let _: &f32 = std::mem::transmute(&1u32);
//~^ ERROR: transmute from a reference to a reference
let _: &f64 = std::mem::transmute(&1f32);
let _: &f32 = std::mem::transmute(&1f64);
//~^ ERROR: transmute from a reference to a reference
//:^ 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);
//~^ ERROR: transmute from a reference to a reference
let _: &GenericParam<f32> = std::mem::transmute(&GenericParam { t: 1u32 });
//~^ ERROR: transmute from a reference to a reference
let u8_ref: &u8 = &0u8;
let u64_ref: &u64 = unsafe { std::mem::transmute(u8_ref) };
let u64_ref: &u64 = &0u64;
let u8_ref: &u8 = unsafe { std::mem::transmute(u64_ref) };
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//~^ ERROR: transmute from a reference to a reference
}

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10 changes: 5 additions & 5 deletions src/tools/clippy/tests/ui/transmute_ptr_to_ptr.stderr
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Expand Up @@ -22,8 22,8 @@ LL | let _: &f32 = std::mem::transmute(&1u32);
error: transmute from a reference to a reference
--> $DIR/transmute_ptr_to_ptr.rs:38:23
|
LL | let _: &f64 = std::mem::transmute(&1f32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(&1f32 as *const f32 as *const f64)`
LL | let _: &f32 = std::mem::transmute(&1f64);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(&1f64 as *const f64 as *const f32)`

error: transmute from a reference to a reference
--> $DIR/transmute_ptr_to_ptr.rs:42:27
Expand All @@ -38,10 38,10 @@ LL | let _: &GenericParam<f32> = std::mem::transmute(&GenericParam { t:
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(&GenericParam { t: 1u32 } as *const GenericParam<u32> as *const GenericParam<f32>)`

error: transmute from a reference to a reference
--> $DIR/transmute_ptr_to_ptr.rs:47:38
--> $DIR/transmute_ptr_to_ptr.rs:47:36
|
LL | let u64_ref: &u64 = unsafe { std::mem::transmute(u8_ref) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(u8_ref as *const u8 as *const u64)`
LL | let u8_ref: &u8 = unsafe { std::mem::transmute(u64_ref) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(u64_ref as *const u64 as *const u8)`

error: aborting due to 7 previous errors