1 files changed, 51 insertions, 0 deletions
diff --git a/src/test/ui/type-alias-impl-trait/implied_bounds_from_types.rs b/src/test/ui/type-alias-impl-trait/implied_bounds_from_types.rs
new file mode 100644
index 000000000..8023cd24f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/implied_bounds_from_types.rs
@@ -0,0 +1,51 @@
+#![feature(type_alias_impl_trait)]
+
+type WithLifetime<T> = impl Equals<SelfType = ()>;
+fn _defining_use<T>() -> WithLifetime<T> {}
+
+trait Convert<'a> {
+    type Witness;
+    fn convert<'b, T: ?Sized>(_proof: &'b Self::Witness, x: &'a T) -> &'b T;
+}
+
+impl<'a> Convert<'a> for () {
+    type Witness = WithLifetime<&'a ()>;
+
+    fn convert<'b, T: ?Sized>(_proof: &'b WithLifetime<&'a ()>, x: &'a T) -> &'b T {
+        // compiler used to think it gets to assume 'a: 'b here because
+        // of the `&'b WithLifetime<&'a ()>` argument
+        x
+        //~^ ERROR lifetime may not live long enough
+    }
+}
+
+fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T {
+    WithLifetime::<&'a ()>::convert_helper::<(), T>(&(), x)
+}
+
+trait Equals {
+    type SelfType;
+    fn convert_helper<'a, 'b, W: Convert<'a, Witness = Self>, T: ?Sized>(
+        proof: &'b Self::SelfType,
+        x: &'a T,
+    ) -> &'b T;
+}
+
+impl<S> Equals for S {
+    type SelfType = Self;
+    fn convert_helper<'a, 'b, W: Convert<'a, Witness = Self>, T: ?Sized>(
+        proof: &'b Self,
+        x: &'a T,
+    ) -> &'b T {
+        W::convert(proof, x)
+    }
+}
+
+fn main() {
+    let r;
+    {
+        let x = String::from("Hello World?");
+        r = extend_lifetime(&x);
+    }
+    println!("{}", r);
+}