1 files changed, 85 insertions, 0 deletions
diff --git a/tests/ui/traits/alias/object-wf.rs b/tests/ui/traits/alias/object-wf.rs
new file mode 100644
index 000000000..1440f02df
--- /dev/null
+++ b/tests/ui/traits/alias/object-wf.rs
@@ -0,0 +1,85 @@
+// check-pass
+
+// This test checks that trait objects involving trait aliases are well-formed.
+
+#![feature(trait_alias)]
+
+trait Obj {}
+
+trait _0 = Send + Sync;
+
+// Just auto traits:
+
+trait _1 = _0 + Send + Sync;
+
+use std::marker::Unpin;
+
+fn _f0() {
+    let _: Box<dyn _0>;
+    let _: Box<dyn _1>;
+    let _: Box<dyn Unpin + _1 + Send + Sync>;
+}
+
+// Include object safe traits:
+
+fn _f1() {
+    let _: Box<dyn Obj + _0>;
+    let _: Box<dyn Obj + _1>;
+    let _: Box<dyn Obj + _1 + _0>;
+}
+
+// And when the object safe trait is in a trait alias:
+
+trait _2 = Obj;
+
+fn _f2() {
+    let _: Box<dyn _2 + _0>;
+    let _: Box<dyn _2 + _1>;
+    let _: Box<dyn _2 + _1 + _0>;
+}
+
+// And it should also work when that trait is has auto traits to the right of it.
+
+trait _3 = Obj + Unpin;
+
+fn _f3() {
+    let _: Box<dyn _3 + _0>;
+    let _: Box<dyn _3 + _1>;
+    let _: Box<dyn _3 + _1 + _0>;
+}
+
+// Nest the trait deeply:
+
+trait _4 = _3;
+trait _5 = _4 + Sync + _0 + Send;
+trait _6 = _5 + Send + _1 + Sync;
+
+fn _f4() {
+    let _: Box<dyn _6 + _0>;
+    let _: Box<dyn _6 + _1>;
+    let _: Box<dyn _6 + _1 + _0>;
+}
+
+// Just nest the trait alone:
+
+trait _7 = _2;
+trait _8 = _7;
+trait _9 = _8;
+
+fn _f5() {
+    let _: Box<dyn _9>;
+}
+
+// First bound is auto trait:
+
+trait _10 = Send + Obj;
+trait _11 = Obj + Send;
+trait _12 = Sync + _11;
+trait _13 = Send + _12;
+
+fn f6() {
+    let _: Box<dyn _10>;
+    let _: Box<dyn _13>;
+}
+
+fn main() {}