From 7308ff63abc95d8ec2a0b7b54c169cb549c2529a Mon Sep 17 00:00:00 2001
From: "Duncan P. N. Exon Smith" <dexonsmith@apple.com>
Date: Tue, 8 Dec 2020 14:54:55 -0800
Subject: [PATCH] ADT: Allow IntrusiveRefCntPtr construction from
 std::unique_ptr, NFC

Allow a `std::unique_ptr` to be moved into the an `IntrusiveRefCntPtr`,
and remove a couple of now-unnecessary `release()` calls.

Differential Revision: https://reviews.llvm.org/D92888
---
 include/llvm/ADT/IntrusiveRefCntPtr.h    |  6 ++++++
 unittests/ADT/IntrusiveRefCntPtrTest.cpp | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/llvm/ADT/IntrusiveRefCntPtr.h b/include/llvm/ADT/IntrusiveRefCntPtr.h
index 173fad3aeaf..dcd35253c5f 100644
--- a/include/llvm/ADT/IntrusiveRefCntPtr.h
+++ b/include/llvm/ADT/IntrusiveRefCntPtr.h
@@ -58,6 +58,7 @@
 #include <atomic>
 #include <cassert>
 #include <cstddef>
+#include <memory>
 
 namespace llvm {
 
@@ -175,6 +176,11 @@ public:
     S.Obj = nullptr;
   }
 
+  template <class X>
+  IntrusiveRefCntPtr(std::unique_ptr<X> S) : Obj(S.release()) {
+    retain();
+  }
+
   template <class X>
   IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X> &S) : Obj(S.get()) {
     retain();
diff --git a/unittests/ADT/IntrusiveRefCntPtrTest.cpp b/unittests/ADT/IntrusiveRefCntPtrTest.cpp
index 3d8041fcbf4..f69239162e3 100644
--- a/unittests/ADT/IntrusiveRefCntPtrTest.cpp
+++ b/unittests/ADT/IntrusiveRefCntPtrTest.cpp
@@ -42,6 +42,17 @@ TYPED_TEST(IntrusiveRefCntPtrTest, RefCountedBaseCopyDoesNotLeak) {
   EXPECT_EQ(0, NumInstances);
 }
 
+TYPED_TEST(IntrusiveRefCntPtrTest, InteropsWithUniquePtr) {
+  EXPECT_EQ(0, NumInstances);
+  {
+    auto S1 = std::make_unique<TypeParam>();
+    IntrusiveRefCntPtr<TypeParam> R1 = std::move(S1);
+    EXPECT_EQ(1, NumInstances);
+    EXPECT_EQ(S1, nullptr);
+  }
+  EXPECT_EQ(0, NumInstances);
+}
+
 struct InterceptRefCounted : public RefCountedBase<InterceptRefCounted> {
   InterceptRefCounted(bool *Released, bool *Retained)
     : Released(Released), Retained(Retained) {}