1 files changed, 121 insertions, 0 deletions
diff --git a/src/test/ui/traits/alias/no-extra-traits.rs b/src/test/ui/traits/alias/no-extra-traits.rs
new file mode 100644
index 000000000..4dad8c0f8
--- /dev/null
+++ b/src/test/ui/traits/alias/no-extra-traits.rs
@@ -0,0 +1,121 @@
+// The purpose of this test is to demonstrate that trait alias expansion
+// preserves the rule that `dyn Trait` may only reference one non-auto trait.
+
+#![feature(trait_alias)]
+
+use std::marker::Unpin;
+
+// Some arbitrary object-safe traits:
+trait ObjA {}
+trait ObjB {}
+
+// Nest a few levels deep:
+trait _0 = ObjA;
+trait _1 = _0;
+
+type _T00 = dyn _0 + ObjB;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T01 = dyn ObjB + _0;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T02 = dyn ObjB + _1;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T03 = dyn _1 + ObjB;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+// Nest some more and in weird ways:
+
+trait _2 = ObjB;
+trait _3 = _2;
+trait _4 = _3;
+
+type _T10 = dyn _2 + _3;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T11 = dyn _3 + _2;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T12 = dyn _2 + _4;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T13 = dyn _4 + _2;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+// Include auto traits:
+
+trait _5 = Sync + ObjB + Send;
+
+type _T20 = dyn _5 + _1;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T21 = dyn _1 + _5;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T22 = dyn _5 + ObjA;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T23 = dyn ObjA + _5;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T24 = dyn Send + _5 + _1 + Sync;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T25 = dyn _1 + Sync + _5 + Send;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T26 = dyn Sync + Send + _5 + ObjA;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T27 = dyn Send + Sync + ObjA + _5;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+// Also nest:
+
+trait _6 = _1 + _5;
+trait _7 = _6;
+trait _8 = _7;
+
+type _T30 = dyn _6;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T31 = dyn _6 + Send;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T32 = dyn Send + _6;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T33 = dyn _8;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T34 = dyn _8 + Send;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T35 = dyn Send + _8;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+// Nest some more:
+
+trait _9 = _5 + Sync;
+trait _10 = Unpin + _9;
+
+type _T40 = dyn _10 + ObjA;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T41 = dyn ObjA + _10;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T42 = dyn _10 + _1;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T43 = dyn Send + _10 + Sync + ObjA;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T44 = dyn ObjA + _10 + Send + Sync;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+type _T45 = dyn Sync + Send + _10 + _1;
+//~^ ERROR only auto traits can be used as additional traits in a trait object [E0225]
+
+fn main() {}