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madsmtmmadsmtm
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Implement Encode and RefEncode for UnsafeCell
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3 files changed

+121
-6
lines changed

3 files changed

+121
-6
lines changed

‎crates/objc2-encode/src/encode.rs

Lines changed: 5 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,4 @@
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use core::cell::UnsafeCell;
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use core::ffi::c_void;
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use core::mem::{self, ManuallyDrop, MaybeUninit};
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use core::num::{
@@ -451,11 +452,12 @@ encode_impls_transparent! {
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// TODO: With specialization: `impl Encode for ManuallyDrop<Box<T>>`
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ManuallyDrop<T: ?Sized>,
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// SAFETY: Guaranteed to have the same in-memory representation `T`.
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//
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// The fact that this has `repr(no_niche)` has no effect on us, since we
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// don't unconditionally implement `Encode` generically over `Option`.
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// (e.g. an `Option<UnsafeCell<&u8>>` impl is not available).
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// The inner field is not public, so may not be stable.
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// TODO: UnsafeCell<T>,
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UnsafeCell<T: ?Sized>,
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// The inner field is not public, so may not be safe.
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// TODO: Pin<T>,
@@ -791,13 +793,10 @@ mod tests {
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assert_eq!(<ManuallyDrop<Option<&u8>>>::ENCODING, u8::ENCODING_REF);
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assert_eq!(<&ManuallyDrop<Option<&u8>>>::ENCODING, <&&u8>::ENCODING);
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// assert_eq!(<UnsafeCell<u8>>::ENCODING, u8::ENCODING);
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assert_eq!(<UnsafeCell<u8>>::ENCODING, u8::ENCODING);
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// assert_eq!(<Pin<u8>>::ENCODING, u8::ENCODING);
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assert_eq!(<MaybeUninit<u8>>::ENCODING, u8::ENCODING);
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assert_eq!(<Wrapping<u8>>::ENCODING, u8::ENCODING);
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// Shouldn't compile
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// assert_eq!(<Option<UnsafeCell<&u8>>>::ENCODING, <&u8>::ENCODING);
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}
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#[test]

‎crates/test-ui/ui/not_encode.rs

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
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//! Verify that certain things we don't want to be encode aren't.
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use core::cell::UnsafeCell;
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use core::ffi::c_void;
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use objc2::encode::Encode;
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use objc2::runtime::Sel;
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fn is_encode<T: Encode>() {}
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fn main() {
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is_encode::<&Sel>();
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is_encode::<&c_void>();
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is_encode::<&()>();
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is_encode::<fn() -> &'static ()>();
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// This should be encode
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is_encode::<UnsafeCell<&u8>>();
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// But this shouldn't be
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is_encode::<Option<UnsafeCell<&u8>>>();
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}

‎crates/test-ui/ui/not_encode.stderr

Lines changed: 96 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,96 @@
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error[E0277]: the trait bound `objc2::runtime::Sel: RefEncode` is not satisfied
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--> ui/not_encode.rs
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|
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| is_encode::<&Sel>();
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| ^^^^ the trait `RefEncode` is not implemented for `objc2::runtime::Sel`
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|
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= note: required for `&objc2::runtime::Sel` to implement `Encode`
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note: required by a bound in `is_encode`
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--> ui/not_encode.rs
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|
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| fn is_encode<T: Encode>() {}
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| ^^^^^^ required by this bound in `is_encode`
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help: consider removing the leading `&`-reference
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|
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11 - is_encode::<&Sel>();
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11 + is_encode::<Sel>();
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|
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error[E0277]: the trait bound `c_void: RefEncode` is not satisfied
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--> ui/not_encode.rs
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|
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| is_encode::<&c_void>();
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| ^^^^^^^ the trait `RefEncode` is not implemented for `c_void`
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|
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= help: the following other types implement trait `RefEncode`:
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*const c_void
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*mut c_void
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= note: required for `&c_void` to implement `Encode`
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note: required by a bound in `is_encode`
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--> ui/not_encode.rs
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|
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| fn is_encode<T: Encode>() {}
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| ^^^^^^ required by this bound in `is_encode`
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error[E0277]: the trait bound `(): RefEncode` is not satisfied
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--> ui/not_encode.rs
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|
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| is_encode::<&()>();
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| ^^^ the trait `RefEncode` is not implemented for `()`
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|
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= note: required for `&()` to implement `Encode`
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note: required by a bound in `is_encode`
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--> ui/not_encode.rs
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|
45+
| fn is_encode<T: Encode>() {}
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| ^^^^^^ required by this bound in `is_encode`
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help: consider removing the leading `&`-reference
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|
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13 - is_encode::<&()>();
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13 + is_encode::<()>();
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|
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error[E0277]: the trait bound `fn() -> &'static (): Encode` is not satisfied
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--> ui/not_encode.rs
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|
56+
| is_encode::<fn() -> &'static ()>();
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| ^^^^^^^^^^^^^^^^^^^ the trait `Encode` is not implemented for `fn() -> &'static ()`
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|
59+
= help: the following other types implement trait `Encode`:
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extern "C" fn() -> Ret
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extern "C" fn(A) -> Ret
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extern "C" fn(A, ...) -> Ret
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extern "C" fn(A, B) -> Ret
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extern "C" fn(A, B, ...) -> Ret
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extern "C" fn(A, B, C) -> Ret
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extern "C" fn(A, B, C, ...) -> Ret
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extern "C" fn(A, B, C, D) -> Ret
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and $N others
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note: required by a bound in `is_encode`
70+
--> ui/not_encode.rs
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|
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| fn is_encode<T: Encode>() {}
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| ^^^^^^ required by this bound in `is_encode`
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75+
error[E0277]: the trait bound `UnsafeCell<&u8>: OptionEncode` is not satisfied
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--> ui/not_encode.rs
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|
78+
| is_encode::<Option<UnsafeCell<&u8>>>();
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| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `OptionEncode` is not implemented for `UnsafeCell<&u8>`
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|
81+
= help: the following other types implement trait `OptionEncode`:
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&'a T
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&'a mut T
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NonNull<T>
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NonNull<c_void>
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NonZeroI16
87+
NonZeroI32
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NonZeroI64
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NonZeroI8
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and $N others
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= note: required for `Option<UnsafeCell<&u8>>` to implement `Encode`
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note: required by a bound in `is_encode`
93+
--> ui/not_encode.rs
94+
|
95+
| fn is_encode<T: Encode>() {}
96+
| ^^^^^^ required by this bound in `is_encode`

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