From 194814065c5c1763db3cff3ac8d7fc260d0631f5 Mon Sep 17 00:00:00 2001
From: Ohad Ravid <ohad.rv@gmail.com>
Date: Tue, 4 Jun 2019 17:22:03 +0200
Subject: [PATCH] Added a test for coherence when a generic type param has a
 default value from an associated type

---
 .../auxiliary/re_rebalance_coherence_lib.rs   |  9 +++++++
 ...herence-default-generic-associated-type.rs | 27 +++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 src/test/run-pass/coherence/re-rebalance-coherence-default-generic-associated-type.rs

diff --git a/src/test/run-pass/coherence/auxiliary/re_rebalance_coherence_lib.rs b/src/test/run-pass/coherence/auxiliary/re_rebalance_coherence_lib.rs
index 41b9d64d5f71e..9a191bad8b0bf 100644
--- a/src/test/run-pass/coherence/auxiliary/re_rebalance_coherence_lib.rs
+++ b/src/test/run-pass/coherence/auxiliary/re_rebalance_coherence_lib.rs
@@ -20,3 +20,12 @@ pub struct BatchInsert<'a, T: 'a, Tab> {
 impl<'a, T:'a, Tab, DB> QueryFragment<DB> for BatchInsert<'a, T, Tab>
 where DB: SupportsDefaultKeyword + Backend,
 {}
+
+pub trait LibToOwned {
+    type Owned;
+}
+
+pub struct LibCow<T: LibToOwned, Owned = <T as LibToOwned>::Owned> {
+    pub t: T,
+    pub o: Owned,
+}
diff --git a/src/test/run-pass/coherence/re-rebalance-coherence-default-generic-associated-type.rs b/src/test/run-pass/coherence/re-rebalance-coherence-default-generic-associated-type.rs
new file mode 100644
index 0000000000000..4168b7a6146a9
--- /dev/null
+++ b/src/test/run-pass/coherence/re-rebalance-coherence-default-generic-associated-type.rs
@@ -0,0 +1,27 @@
+// run-pass
+// aux-build:re_rebalance_coherence_lib.rs
+
+#![allow(dead_code)]
+#![feature(re_rebalance_coherence)]
+// check that a generic type with a default value from an associated type can be used without
+// specifying the value, and without invoking coherence errors.
+
+extern crate re_rebalance_coherence_lib as lib;
+use lib::*;
+
+struct MyString {}
+
+impl LibToOwned for MyString {
+    type Owned = String;
+}
+
+impl PartialEq<MyString> for LibCow<MyString> {
+    fn eq(&self, _other: &MyString) -> bool {
+        // Test that the default type is used.
+        let _s: &String = &self.o;
+
+        false
+    }
+}
+
+fn main() {}