Add tests

tests/ui/cfg/proper_unpin.rs

@@ -0,0 +1,31 @@
+// compile-fail
+
+use pin_project::pin_project;
+use std::{marker::PhantomPinned, pin::Pin};
+
+#[pin_project]
+struct Foo<T> {
+    #[cfg(any())]
+    #[pin]
+    inner: T,
+    #[cfg(not(any()))]
+    inner: T,
+}
+
+#[pin_project]
+struct Bar<T> {
+    #[cfg(any())]
+    inner: T,
+    #[cfg(not(any()))]
+    #[pin]
+    inner: T,
+}
+
+fn is_unpin<T: Unpin>() {}
+
+fn baz<T, U>() {
+    is_unpin::<Foo<PhantomPinned>>(); // Ok
+    is_unpin::<Bar<PhantomPinned>>(); //~ ERROR E0277
+}
+
+fn main() {}

tests/ui/cfg/proper_unpin.stderr

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+error[E0277]: the trait bound `std::marker::PhantomPinned: std::marker::Unpin` is not satisfied in `UnpinStructBar<std::marker::PhantomPinned>`
+  --> $DIR/proper_unpin.rs:28:5
+   |
+24 | fn is_unpin<T: Unpin>() {}
+   | ----------------------- required by `is_unpin`
+...
+28 |     is_unpin::<Bar<PhantomPinned>>(); //~ ERROR E0277
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ within `UnpinStructBar<std::marker::PhantomPinned>`, the trait `std::marker::Unpin` is not implemented for `std::marker::PhantomPinned`
+   |
+   = help: the following implementations were found:
+             <std::marker::PhantomPinned as std::marker::Unpin>
+   = note: required because it appears within the type `UnpinStructBar<std::marker::PhantomPinned>`
+   = note: required because of the requirements on the impl of `std::marker::Unpin` for `Bar<std::marker::PhantomPinned>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/unsafe_unpin/proper_unpin.rs

@@ -0,0 +1,21 @@
+// compile-fail
+
+use pin_project::{pin_project, UnsafeUnpin};
+use std::{marker::PhantomPinned, pin::Pin};
+
+#[pin_project(UnsafeUnpin)]
+struct Foo<T, U> {
+    #[pin]
+    inner: T,
+    other: U,
+}
+
+unsafe impl<T: Unpin, U> UnsafeUnpin for Foo<T, U> {}
+
+fn is_unpin<T: Unpin>() {}
+
+fn bar<T, U>() {
+    is_unpin::<Foo<PhantomPinned, U>>(); //~ ERROR E0277
+}
+
+fn main() {}

tests/ui/unsafe_unpin/proper_unpin.stderr

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+error[E0277]: the trait bound `std::marker::PhantomPinned: std::marker::Unpin` is not satisfied
+  --> $DIR/proper_unpin.rs:18:5
+   |
+15 | fn is_unpin<T: Unpin>() {}
+   | ----------------------- required by `is_unpin`
+...
+18 |     is_unpin::<Foo<PhantomPinned, U>>(); //~ ERROR E0277
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::marker::Unpin` is not implemented for `std::marker::PhantomPinned`
+   |
+   = help: the following implementations were found:
+             <std::marker::PhantomPinned as std::marker::Unpin>
+   = note: required because of the requirements on the impl of `pin_project::UnsafeUnpin` for `Foo<std::marker::PhantomPinned, U>`
+   = note: required because of the requirements on the impl of `pin_project::UnsafeUnpin` for `pin_project::__private::Wrapper<Foo<std::marker::PhantomPinned, U>>`
+   = note: required because of the requirements on the impl of `std::marker::Unpin` for `Foo<std::marker::PhantomPinned, U>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.