add test

Author: aliemjay

Diff for: tests/ui/implied-bounds/normalization.rs

@@ -0,0 +1,58 @@
+// Test that we get implied bounds from complex projections after normalization.
+
+// check-pass
+
+// implementations wil ensure that
+// WF(<T as Combine<'a>>::Ty) implies T: 'a
+trait Combine<'a> {
+    type Ty;
+}
+
+impl<'a, T: 'a> Combine<'a> for Box<T> {
+    type Ty = &'a T;
+}
+
+// ======= Wrappers ======
+
+// normalizes to a projection
+struct WrapA<T>(T);
+impl<'a, T> Combine<'a> for WrapA<T>
+where
+    T: Combine<'a>,
+{
+    type Ty = T::Ty;
+}
+
+// <WrapB<T> as Combine<'a>>::Ty normalizes to a type variable ?X
+// with constraint `<T as Combine<'a>>::Ty == ?X`
+struct WrapB<T>(T);
+impl<'a, X, T> Combine<'a> for WrapB<T>
+where
+    T: Combine<'a, Ty = X>,
+{
+    type Ty = X;
+}
+
+// <WrapC<T> as Combine<'a>>::Ty normalizes to `&'a &'?x ()`
+// with constraint `<T as Combine<'a>>::Ty == &'a &'?x ()`
+struct WrapC<T>(T);
+impl<'a, 'x: 'a, T> Combine<'a> for WrapC<T>
+where
+    T: Combine<'a, Ty = &'a &'x ()>,
+{
+    type Ty = &'a &'x ();
+}
+
+//==== Test implied bounds ======
+
+fn test_wrap<'a, 'b, 'c1, 'c2, A, B>(
+    _: <WrapA<Box<A>> as Combine<'a>>::Ty,        // normalized: &'a A
+    _: <WrapB<Box<B>> as Combine<'b>>::Ty,        // normalized: &'b B
+    _: <WrapC<Box<&'c1 ()>> as Combine<'c2>>::Ty, // normalized: &'c2 &'c1 ()
+) {
+    None::<&'a A>;
+    None::<&'b B>;
+    None::<&'c2 &'c1 ()>;
+}
+
+fn main() {}