1 files changed, 125 insertions, 0 deletions
diff --git a/src/test/ui/span/vec-must-not-hide-type-from-dropck.rs b/src/test/ui/span/vec-must-not-hide-type-from-dropck.rs
new file mode 100644
index 000000000..9bfbfab06
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+++ b/src/test/ui/span/vec-must-not-hide-type-from-dropck.rs
@@ -0,0 +1,125 @@
+// Checking that `Vec<T>` cannot hide lifetimes within `T` when `T`
+// implements `Drop` and might access methods of values that have
+// since been deallocated.
+//
+// In this case, the values in question hold (non-zero) unique-ids
+// that zero themselves out when dropped, and are wrapped in another
+// type with a destructor that asserts that the ids it references are
+// indeed non-zero (i.e., effectively checking that the id's are not
+// dropped while there are still any outstanding references).
+//
+// However, the values in question are also formed into a
+// cyclic-structure, ensuring that there is no way for all of the
+// conditions above to be satisfied, meaning that if the dropck is
+// sound, it should reject this code.
+
+
+
+use std::cell::Cell;
+use id::Id;
+
+mod s {
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    static S_COUNT: AtomicUsize = AtomicUsize::new(0);
+
+    /// generates globally unique count (global across the current
+    /// process, that is)
+    pub fn next_count() -> usize {
+        S_COUNT.fetch_add(1, Ordering::SeqCst) + 1
+    }
+}
+
+mod id {
+    use s;
+
+    /// Id represents a globally unique identifier (global across the
+    /// current process, that is). When dropped, it automatically
+    /// clears its `count` field, but leaves `orig_count` untouched,
+    /// so that if there are subsequent (erroneous) invocations of its
+    /// method (which is unsound), we can observe it by seeing that
+    /// the `count` is 0 while the `orig_count` is non-zero.
+    #[derive(Debug)]
+    pub struct Id {
+        orig_count: usize,
+        count: usize,
+    }
+
+    impl Id {
+        /// Creates an `Id` with a globally unique count.
+        pub fn new() -> Id {
+            let c = s::next_count();
+            println!("building Id {}", c);
+            Id { orig_count: c, count: c }
+        }
+        /// returns the `count` of self; should be non-zero if
+        /// everything is working.
+        pub fn count(&self) -> usize {
+            println!("Id::count on {} returns {}", self.orig_count, self.count);
+            self.count
+        }
+    }
+
+    impl Drop for Id {
+        fn drop(&mut self) {
+            println!("dropping Id {}", self.count);
+            self.count = 0;
+        }
+    }
+}
+
+trait HasId {
+    fn count(&self) -> usize;
+}
+
+#[derive(Debug)]
+struct CheckId<T:HasId> {
+    v: T
+}
+
+#[allow(non_snake_case)]
+fn CheckId<T:HasId>(t: T) -> CheckId<T> { CheckId{ v: t } }
+
+impl<T:HasId> Drop for CheckId<T> {
+    fn drop(&mut self) {
+        assert!(self.v.count() > 0);
+    }
+}
+
+#[derive(Debug)]
+struct C<'a> {
+    id: Id,
+    v: Vec<CheckId<Cell<Option<&'a C<'a>>>>>,
+}
+
+impl<'a> HasId for Cell<Option<&'a C<'a>>> {
+    fn count(&self) -> usize {
+        match self.get() {
+            None => 1,
+            Some(c) => c.id.count(),
+        }
+    }
+}
+
+impl<'a> C<'a> {
+    fn new() -> C<'a> {
+        C { id: Id::new(), v: Vec::new() }
+    }
+}
+
+fn f() {
+    let (mut c1, mut c2);
+    c1 = C::new();
+    c2 = C::new();
+
+    c1.v.push(CheckId(Cell::new(None)));
+    c2.v.push(CheckId(Cell::new(None)));
+    c1.v[0].v.set(Some(&c2));
+    //~^ ERROR `c2` does not live long enough
+    c2.v[0].v.set(Some(&c1));
+    //~^ ERROR `c1` does not live long enough
+}
+
+fn main() {
+    f();
+}