From 4ef6c0908bbadea8b827aaaf0cb51e543bef5f3d Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Tue, 29 Apr 2014 00:14:27 +0000
Subject: [PATCH] [ADT] Teach PointerUnion to support assignment directly from
 nullptr to clear it out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207471 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/PointerUnion.h    | 18 ++++++++++++++++++
 unittests/ADT/PointerUnionTest.cpp |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/include/llvm/ADT/PointerUnion.h b/include/llvm/ADT/PointerUnion.h
index dafd0e05109..a6dddd27762 100644
--- a/include/llvm/ADT/PointerUnion.h
+++ b/include/llvm/ADT/PointerUnion.h
@@ -154,6 +154,12 @@ namespace llvm {
          "Can't get the address because PointerLikeTypeTraits changes the ptr");
       return (PT1 *)Val.getAddrOfPointer();
     }
+
+    /// \brief Assignment from nullptr which just clears the union.
+    const PointerUnion &operator=(std::nullptr_t) {
+      Val.initWithPointer(nullptr);
+      return *this;
+    }
     
     /// Assignment operators - Allow assigning into this union from either
     /// pointer type, setting the discriminator to remember what it came from.
@@ -298,6 +304,12 @@ namespace llvm {
       if (is<T>()) return get<T>();
       return T();
     }
+
+    /// \brief Assignment from nullptr which just clears the union.
+    const PointerUnion3 &operator=(std::nullptr_t) {
+      Val = nullptr;
+      return *this;
+    }
     
     /// Assignment operators - Allow assigning into this union from either
     /// pointer type, setting the discriminator to remember what it came from.
@@ -407,6 +419,12 @@ namespace llvm {
       if (is<T>()) return get<T>();
       return T();
     }
+
+    /// \brief Assignment from nullptr which just clears the union.
+    const PointerUnion4 &operator=(std::nullptr_t) {
+      Val = nullptr;
+      return *this;
+    }
     
     /// Assignment operators - Allow assigning into this union from either
     /// pointer type, setting the discriminator to remember what it came from.
diff --git a/unittests/ADT/PointerUnionTest.cpp b/unittests/ADT/PointerUnionTest.cpp
index 23a833310d2..3bfb79cee49 100644
--- a/unittests/ADT/PointerUnionTest.cpp
+++ b/unittests/ADT/PointerUnionTest.cpp
@@ -46,6 +46,12 @@ TEST_F(PointerUnionTest, Null) {
   EXPECT_TRUE((bool)a);
   EXPECT_TRUE((bool)b);
   EXPECT_FALSE(n);
+
+  EXPECT_NE(n, b);
+  EXPECT_EQ(b, c);
+  b = nullptr;
+  EXPECT_EQ(n, b);
+  EXPECT_NE(b, c);
 }
 
 TEST_F(PointerUnionTest, Is) {