6 files changed, 92 insertions, 0 deletions
diff --git a/src/test/ui/sized/coinductive-1-gat.rs b/src/test/ui/sized/coinductive-1-gat.rs
new file mode 100644
index 000000000..cdf70920f
--- /dev/null
+++ b/src/test/ui/sized/coinductive-1-gat.rs
@@ -0,0 +1,14 @@
+// check-pass
+struct Node<C: Trait>(C::Assoc::<Self>);
+
+trait Trait {
+    type Assoc<T>;
+}
+
+impl Trait for Vec<()> {
+    type Assoc<T> = Vec<T>;
+}
+
+fn main() {
+    let _ = Node::<Vec<()>>(Vec::new());
+}
diff --git a/src/test/ui/sized/coinductive-1.rs b/src/test/ui/sized/coinductive-1.rs
new file mode 100644
index 000000000..7bcd0f1fd
--- /dev/null
+++ b/src/test/ui/sized/coinductive-1.rs
@@ -0,0 +1,14 @@
+// check-pass
+struct Node<C: Trait<Self>>(C::Assoc);
+
+trait Trait<T> {
+    type Assoc;
+}
+
+impl<T> Trait<T> for Vec<()> {
+    type Assoc = Vec<T>;
+}
+
+fn main() {
+    let _ = Node::<Vec<()>>(Vec::new());
+}
diff --git a/src/test/ui/sized/coinductive-2.rs b/src/test/ui/sized/coinductive-2.rs
new file mode 100644
index 000000000..212274d2e
--- /dev/null
+++ b/src/test/ui/sized/coinductive-2.rs
@@ -0,0 +1,28 @@
+// run-pass
+struct Node<C: CollectionFactory<Self>> {
+    _children: C::Collection,
+}
+
+trait CollectionFactory<T> {
+    type Collection;
+}
+
+impl<T> CollectionFactory<T> for Vec<()> {
+    type Collection = Vec<T>;
+}
+
+trait Collection<T>: Sized {
+    fn push(&mut self, v: T);
+}
+
+impl<T> Collection<T> for Vec<T> {
+    fn push(&mut self, v: T) {
+        self.push(v)
+    }
+}
+
+fn main() {
+    let _ = Node::<Vec<()>> {
+        _children: Vec::new(),
+    };
+}
diff --git a/src/test/ui/sized/recursive-type-1.rs b/src/test/ui/sized/recursive-type-1.rs
new file mode 100644
index 000000000..cd6805967
--- /dev/null
+++ b/src/test/ui/sized/recursive-type-1.rs
@@ -0,0 +1,10 @@
+// check-pass
+trait A { type Assoc; }
+
+impl A for () {
+    // FIXME: it would be nice for this to at least cause a warning.
+    type Assoc = Foo<()>;
+}
+struct Foo<T: A>(T::Assoc);
+
+fn main() {}
diff --git a/src/test/ui/sized/recursive-type-2.rs b/src/test/ui/sized/recursive-type-2.rs
new file mode 100644
index 000000000..7d95417a6
--- /dev/null
+++ b/src/test/ui/sized/recursive-type-2.rs
@@ -0,0 +1,13 @@
+// build-fail
+//~^ ERROR cycle detected when computing layout of `Foo<()>`
+
+trait A { type Assoc: ?Sized; }
+
+impl A for () {
+    type Assoc = Foo<()>;
+}
+struct Foo<T: A>(T::Assoc);
+
+fn main() {
+    let x: Foo<()>;
+}
diff --git a/src/test/ui/sized/recursive-type-2.stderr b/src/test/ui/sized/recursive-type-2.stderr
new file mode 100644
index 000000000..d0e6e9db0
--- /dev/null
+++ b/src/test/ui/sized/recursive-type-2.stderr
@@ -0,0 +1,13 @@
+error[E0391]: cycle detected when computing layout of `Foo<()>`
+   |
+   = note: ...which requires computing layout of `<() as A>::Assoc`...
+   = note: ...which again requires computing layout of `Foo<()>`, completing the cycle
+note: cycle used when elaborating drops for `main`
+  --> $DIR/recursive-type-2.rs:11:1
+   |
+LL | fn main() {
+   | ^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0391`.