Implement !Unpin option

.github/workflows/ci.yml

@@ -27,8 +27,8 @@ jobs:
           # This is the minimum supported Rust version of this crate.
           # When updating this, the reminder to update the minimum supported
           # Rust version in README.md.
-          - build: 1.33.0
-            rust: 1.33.0
+          - build: 1.34.0
+            rust: 1.34.0
           - build: 1.36.0
             rust: 1.36.0
           - build: 1.37.0

README.md

@@ -11,8 +11,8 @@
 [docs-url]: https://docs.rs/pin-project
 [license-badge]: https://img.shields.io/crates/l/pin-project.svg
 [license]: #license
-[rustc-badge]: https://img.shields.io/badge/rustc-1.33+-lightgray.svg
-[rustc-url]: https://blog.rust-lang.org/2019/02/28/Rust-1.33.0.html
+[rustc-badge]: https://img.shields.io/badge/rustc-1.34+-lightgray.svg
+[rustc-url]: https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html
 
 A crate for safe and ergonomic pin-projection.
 
@@ -29,7 +29,7 @@ Add this to your `Cargo.toml`:
 pin-project = "0.4"
 ```
 
-The current pin-project requires Rust 1.33 or later.
+The current pin-project requires Rust 1.34 or later.
 
 ## Examples
 

ci.sh

@@ -12,7 +12,7 @@ echo "Running 'cargo fmt -- --check'"
 cargo +nightly fmt --all -- --check
 
 echo "Running 'cargo clippy'"
-cargo +nightly clippy --all --all-features
+cargo +nightly clippy --all --all-features --all-targets
 
 echo "Running 'cargo test'"
 cargo +nightly test --all --all-features

pin-project-internal/src/lib.rs

@@ -220,6 +220,40 @@ use crate::utils::{Immutable, Mutable, Owned};
 ///
 /// See also [`project`] and [`project_ref`] attributes.
 ///
+/// ## `!Unpin`
+///
+/// If you want to ensure that [`Unpin`] is not implemented, use the `!Unpin`
+/// argument to `#[pin_project]`.
+///
+/// ```rust
+/// use pin_project::pin_project;
+///
+/// #[pin_project(!Unpin)]
+/// struct Struct<T, U> {
+///     #[pin]
+///     pinned: T,
+///     unpinned: U,
+/// }
+/// ```
+///
+/// You can also ensure `!Unpin` by using `#[pin]` attribute for [`PhantomPinned`] field.
+///
+/// ```rust
+/// use pin_project::pin_project;
+/// use std::marker::PhantomPinned;
+///
+/// #[pin_project]
+/// struct Struct<T, U> {
+///     #[pin]
+///     pinned: T,
+///     unpinned: U,
+///     #[pin]
+///     _pin: PhantomPinned,
+/// }
+/// ```
+///
+/// Note that using [`PhantomPinned`] without `#[pin]` attribute has no effect.
+///
 /// ## `UnsafeUnpin`
 ///
 /// If you want to implement [`Unpin`] manually, you must use the `UnsafeUnpin`