1 files changed, 169 insertions, 0 deletions
diff --git a/third_party/rust/pin-project-lite/tests/drop_order.rs b/third_party/rust/pin-project-lite/tests/drop_order.rs
new file mode 100644
index 0000000000..6e5deaf154
--- /dev/null
+++ b/third_party/rust/pin-project-lite/tests/drop_order.rs
@@ -0,0 +1,169 @@
+#![warn(rust_2018_idioms, single_use_lifetimes)]
+
+// Refs: https://doc.rust-lang.org/reference/destructors.html
+
+use std::{cell::Cell, panic, pin::Pin, thread};
+
+use pin_project_lite::pin_project;
+
+struct D<'a>(&'a Cell<usize>, usize);
+
+impl Drop for D<'_> {
+    fn drop(&mut self) {
+        if !thread::panicking() {
+            let old = self.0.replace(self.1);
+            assert_eq!(old, self.1 - 1);
+        }
+    }
+}
+
+pin_project! {
+#[project = StructPinnedProj]
+#[project_ref = StructPinnedProjRef]
+#[project_replace = StructPinnedProjReplace]
+struct StructPinned<'a> {
+    #[pin]
+    f1: D<'a>,
+    #[pin]
+    f2: D<'a>,
+}
+}
+
+pin_project! {
+#[project = StructUnpinnedProj]
+#[project_ref = StructUnpinnedProjRef]
+#[project_replace = StructUnpinnedProjReplace]
+struct StructUnpinned<'a> {
+    f1: D<'a>,
+    f2: D<'a>,
+}
+}
+
+pin_project! {
+#[project_replace = EnumProjReplace]
+enum Enum<'a> {
+    #[allow(dead_code)] // false positive that fixed in Rust 1.38
+    StructPinned {
+        #[pin]
+        f1: D<'a>,
+        #[pin]
+        f2: D<'a>,
+    },
+    #[allow(dead_code)] // false positive that fixed in Rust 1.38
+    StructUnpinned {
+        f1: D<'a>,
+        f2: D<'a>,
+    },
+}
+}
+
+#[test]
+fn struct_pinned() {
+    {
+        let c = Cell::new(0);
+        let _x = StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
+    }
+    {
+        let c = Cell::new(0);
+        let mut x = StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
+        let y = Pin::new(&mut x);
+        let _z = y.project_replace(StructPinned { f1: D(&c, 3), f2: D(&c, 4) });
+    }
+}
+
+#[test]
+fn struct_unpinned() {
+    {
+        let c = Cell::new(0);
+        let _x = StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
+    }
+    {
+        let c = Cell::new(0);
+        let mut x = StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
+        let y = Pin::new(&mut x);
+        let _z = y.project_replace(StructUnpinned { f1: D(&c, 3), f2: D(&c, 4) });
+    }
+}
+
+#[test]
+fn enum_struct() {
+    {
+        let c = Cell::new(0);
+        let _x = Enum::StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
+    }
+    {
+        let c = Cell::new(0);
+        let mut x = Enum::StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
+        let y = Pin::new(&mut x);
+        let _z = y.project_replace(Enum::StructPinned { f1: D(&c, 3), f2: D(&c, 4) });
+    }
+
+    {
+        let c = Cell::new(0);
+        let _x = Enum::StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
+    }
+    {
+        let c = Cell::new(0);
+        let mut x = Enum::StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
+        let y = Pin::new(&mut x);
+        let _z = y.project_replace(Enum::StructUnpinned { f1: D(&c, 3), f2: D(&c, 4) });
+    }
+}
+
+// https://github.com/rust-lang/rust/issues/47949
+// https://github.com/taiki-e/pin-project/pull/194#discussion_r419098111
+#[allow(clippy::many_single_char_names)]
+#[test]
+fn project_replace_panic() {
+    pin_project! {
+    #[project_replace = SProjReplace]
+    struct S<T, U> {
+        #[pin]
+        pinned: T,
+        unpinned: U,
+    }
+    }
+
+    struct D<'a>(&'a mut bool, bool);
+    impl Drop for D<'_> {
+        fn drop(&mut self) {
+            *self.0 = true;
+            if self.1 {
+                panic!();
+            }
+        }
+    }
+
+    let (mut a, mut b, mut c, mut d) = (false, false, false, false);
+    let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        let mut x = S { pinned: D(&mut a, true), unpinned: D(&mut b, false) };
+        let _y = Pin::new(&mut x)
+            .project_replace(S { pinned: D(&mut c, false), unpinned: D(&mut d, false) });
+        // Previous `x.pinned` was dropped and panicked when `project_replace` is
+        // called, so this is unreachable.
+        unreachable!();
+    }));
+    assert!(res.is_err());
+    assert!(a);
+    assert!(b);
+    assert!(c);
+    assert!(d);
+
+    let (mut a, mut b, mut c, mut d) = (false, false, false, false);
+    let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        let mut x = S { pinned: D(&mut a, false), unpinned: D(&mut b, true) };
+        {
+            let _y = Pin::new(&mut x)
+                .project_replace(S { pinned: D(&mut c, false), unpinned: D(&mut d, false) });
+            // `_y` (previous `x.unpinned`) live to the end of this scope, so
+            // this is not unreachable.
+            // unreachable!();
+        }
+        unreachable!();
+    }));
+    assert!(res.is_err());
+    assert!(a);
+    assert!(b);
+    assert!(c);
+    assert!(d);
+}