From 9ea653eed4db0098402978453fcf2cfc382caac8 Mon Sep 17 00:00:00 2001
From: Thayne McCombs <astrothayne@gmail.com>
Date: Sun, 4 Sep 2016 22:24:57 -0600
Subject: [PATCH 1/4] Allow using Unique with interfaces

---
 std/typecons.d | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/std/typecons.d b/std/typecons.d
index 62cf0fb6b8f..96ef731104a 100644
--- a/std/typecons.d
+++ b/std/typecons.d
@@ -56,7 +56,7 @@ class object, in which case Unique behaves polymorphically too.
 struct Unique(T)
 {
 /** Represents a reference to $(D T). Resolves to $(D T*) if $(D T) is a value type. */
-static if (is(T:Object))
+static if (is(T == class) || is(T == interface))
     alias RefT = T;
 else
     alias RefT = T*;
@@ -261,6 +261,35 @@ private:
     assert(!ub2.isEmpty);
 }
 
+@system unittest
+{
+    debug(Unique) writeln("Unique interface");
+    interface Bar
+    {
+        int val() const;
+    }
+    class BarImpl : Bar
+    {
+        ~this() { debug(Unique) writeln("    C destructor"); }
+        int val() const { return 4; };
+    }
+    alias UBar = Unique!Bar;
+    UBar g(UBar u)
+    {
+        debug(Unique) writeln("inside g");
+        return u.release;
+    }
+    auto ub = UBar(new BarImpl);
+    assert(!ub.isEmpty);
+    assert(ub.val == 4);
+    static assert(!__traits(compiles, {auto ub3 = g(ub);}));
+    debug(Unique) writeln("Calling g");
+    auto ub2 = g(ub.release);
+    debug(Unique) writeln("Returned from g");
+    assert(ub.isEmpty);
+    assert(!ub2.isEmpty);
+}
+
 @system unittest
 {
     debug(Unique) writeln("Unique struct");

From b6c2e381e9d3ee67c3bbf73d0d3740018e384677 Mon Sep 17 00:00:00 2001
From: Thayne McCombs <astrothayne@gmail.com>
Date: Mon, 5 Sep 2016 19:24:21 -0600
Subject: [PATCH 2/4] Add a little documentation

---
 std/typecons.d | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/std/typecons.d b/std/typecons.d
index 96ef731104a..262e44ff169 100644
--- a/std/typecons.d
+++ b/std/typecons.d
@@ -51,7 +51,7 @@ Encapsulates unique ownership of a resource.  Resource of type $(D T) is
 deleted at the end of the scope, unless it is transferred.  The
 transfer can be explicit, by calling $(D release), or implicit, when
 returning Unique from a function. The resource can be a polymorphic
-class object, in which case Unique behaves polymorphically too.
+class object or instance of an interface, in which case Unique behaves polymorphically too.
 */
 struct Unique(T)
 {

From 7cbea7473ad16e52e7d5973793aa0dea5a9b9da4 Mon Sep 17 00:00:00 2001
From: Thayne McCombs <astrothayne@gmail.com>
Date: Thu, 16 Mar 2017 21:40:55 -0600
Subject: [PATCH 3/4] Remove trailing space

---
 std/typecons.d | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/std/typecons.d b/std/typecons.d
index 6af4a3dc6a7..879a635f46e 100644
--- a/std/typecons.d
+++ b/std/typecons.d
@@ -61,7 +61,7 @@ $(D T) to deallocate or clean up any non-GC resources.
 If it is desirable to persist a $(D Unique!T) outside of its original
 scope, then it can be transferred.  The transfer can be explicit, by
 calling $(D release), or implicit, when returning Unique from a
-function. The resource $(D T) can be a polymorphic class object or 
+function. The resource $(D T) can be a polymorphic class object or
 instance of an interface, in which case Unique behaves polymorphically
 too.
 

From 70a9e2a5030a85a8001c534f06952c9e777da053 Mon Sep 17 00:00:00 2001
From: Thayne McCombs <astrothayne@gmail.com>
Date: Thu, 16 Mar 2017 22:13:02 -0600
Subject: [PATCH 4/4] Improve unit test for Unique with interface

---
 std/typecons.d | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/std/typecons.d b/std/typecons.d
index 879a635f46e..2b44c751b6e 100644
--- a/std/typecons.d
+++ b/std/typecons.d
@@ -290,7 +290,15 @@ private:
     }
     class BarImpl : Bar
     {
-        ~this() { debug(Unique) writeln("    C destructor"); }
+        static int count;
+        this()
+        {
+            count++;
+        }
+        ~this()
+        {
+            count--;
+        }
         int val() const { return 4; };
     }
     alias UBar = Unique!Bar;
@@ -299,7 +307,13 @@ private:
         debug(Unique) writeln("inside g");
         return u.release;
     }
+    void consume(UBar u)
+    {
+        assert(u.val() == 4);
+        // Resource automatically deleted here
+    }
     auto ub = UBar(new BarImpl);
+    assert(BarImpl.count == 1);
     assert(!ub.isEmpty);
     assert(ub.val == 4);
     static assert(!__traits(compiles, {auto ub3 = g(ub);}));
@@ -308,6 +322,8 @@ private:
     debug(Unique) writeln("Returned from g");
     assert(ub.isEmpty);
     assert(!ub2.isEmpty);
+    consume(ub2.release);
+    assert(BarImpl.count == 0);
 }
 
 @system unittest