156 lines
5.4 KiB
Rust
156 lines
5.4 KiB
Rust
// Original code (./struct-default.rs):
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//
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// ```rust
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// #![allow(dead_code)]
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//
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// use pin_project::pin_project;
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//
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// #[pin_project]
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// struct Struct<T, U> {
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// #[pin]
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// pinned: T,
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// unpinned: U,
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// }
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//
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// fn main() {}
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// ```
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#![allow(dead_code, unused_imports, unused_parens, unknown_lints, renamed_and_removed_lints)]
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#![allow(clippy::needless_lifetimes)]
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use pin_project::pin_project;
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// #[pin_project]
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struct Struct<T, U> {
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// #[pin]
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pinned: T,
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unpinned: U,
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}
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const _: () = {
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struct __StructProjection<'pin, T, U>
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where
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Struct<T, U>: 'pin,
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{
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pinned: ::pin_project::__private::Pin<&'pin mut (T)>,
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unpinned: &'pin mut (U),
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}
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struct __StructProjectionRef<'pin, T, U>
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where
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Struct<T, U>: 'pin,
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{
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pinned: ::pin_project::__private::Pin<&'pin (T)>,
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unpinned: &'pin (U),
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}
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impl<T, U> Struct<T, U> {
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fn project<'pin>(
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self: ::pin_project::__private::Pin<&'pin mut Self>,
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) -> __StructProjection<'pin, T, U> {
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unsafe {
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let Self { pinned, unpinned } = self.get_unchecked_mut();
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__StructProjection {
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pinned: ::pin_project::__private::Pin::new_unchecked(pinned),
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unpinned,
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}
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}
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}
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fn project_ref<'pin>(
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self: ::pin_project::__private::Pin<&'pin Self>,
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) -> __StructProjectionRef<'pin, T, U> {
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unsafe {
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let Self { pinned, unpinned } = self.get_ref();
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__StructProjectionRef {
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pinned: ::pin_project::__private::Pin::new_unchecked(pinned),
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unpinned,
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}
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}
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}
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}
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// Ensure that it's impossible to use pin projections on a #[repr(packed)]
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// struct.
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//
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// Taking a reference to a packed field is UB, and applying
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// `#[forbid(unaligned_references)]` makes sure that doing this is a hard error.
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//
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// If the struct ends up having #[repr(packed)] applied somehow,
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// this will generate an (unfriendly) error message. Under all reasonable
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// circumstances, we'll detect the #[repr(packed)] attribute, and generate
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// a much nicer error above.
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//
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// See https://github.com/taiki-e/pin-project/pull/34 for more details.
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#[forbid(unaligned_references, safe_packed_borrows)]
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fn __assert_not_repr_packed<T, U>(this: &Struct<T, U>) {
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let _ = &this.pinned;
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let _ = &this.unpinned;
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}
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// Automatically create the appropriate conditional `Unpin` implementation.
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//
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// Basically this is equivalent to the following code:
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//
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// ```rust
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// impl<T, U> Unpin for Struct<T, U> where T: Unpin {}
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// ```
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//
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// However, if struct is public and there is a private type field,
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// this would cause an E0446 (private type in public interface).
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//
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// When RFC 2145 is implemented (rust-lang/rust#48054),
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// this will become a lint, rather then a hard error.
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//
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// As a workaround for this, we generate a new struct, containing all of
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// the pinned fields from our #[pin_project] type. This struct is declared
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// within a function, which makes it impossible to be named by user code.
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// This guarantees that it will use the default auto-trait impl for Unpin -
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// that is, it will implement Unpin iff all of its fields implement Unpin.
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// This type can be safely declared as 'public', satisfying the privacy
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// checker without actually allowing user code to access it.
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//
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// This allows users to apply the #[pin_project] attribute to types
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// regardless of the privacy of the types of their fields.
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//
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// See also https://github.com/taiki-e/pin-project/pull/53.
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struct __Struct<'pin, T, U> {
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__pin_project_use_generics: ::pin_project::__private::AlwaysUnpin<
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'pin,
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(::pin_project::__private::PhantomData<T>, ::pin_project::__private::PhantomData<U>),
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>,
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__field0: T,
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}
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impl<'pin, T, U> ::pin_project::__private::Unpin for Struct<T, U> where
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__Struct<'pin, T, U>: ::pin_project::__private::Unpin
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{
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}
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// A dummy impl of `UnsafeUnpin`, to ensure that the user cannot implement it.
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//
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// To ensure that users don't accidentally write a non-functional `UnsafeUnpin`
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// impls, we emit one ourselves. If the user ends up writing an `UnsafeUnpin`
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// impl, they'll get a "conflicting implementations of trait" error when
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// coherence checks are run.
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#[doc(hidden)]
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unsafe impl<'pin, T, U> ::pin_project::UnsafeUnpin for Struct<T, U> where
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__Struct<'pin, T, U>: ::pin_project::__private::Unpin
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{
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}
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// Ensure that struct does not implement `Drop`.
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//
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// If you attempt to provide an Drop impl, the blanket impl will
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// then apply to your type, causing a compile-time error due to
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// the conflict with the second impl.
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trait StructMustNotImplDrop {}
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#[allow(clippy::drop_bounds, drop_bounds)]
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impl<T: ::pin_project::__private::Drop> StructMustNotImplDrop for T {}
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impl<T, U> StructMustNotImplDrop for Struct<T, U> {}
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// A dummy impl of `PinnedDrop`, to ensure that users don't accidentally
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// write a non-functional `PinnedDrop` impls.
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#[doc(hidden)]
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impl<T, U> ::pin_project::__private::PinnedDrop for Struct<T, U> {
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unsafe fn drop(self: ::pin_project::__private::Pin<&mut Self>) {}
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}
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};
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fn main() {}
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