Allow Optionals to be compared to None

This is something like nullopt in std::experimental::optional. Optional
could already be constructed from None, so this seems like an obvious
extension from there.

I have a use in a future patch for Clang, though it may not go that
way/end up used - so this seemed worth committing now regardless.

llvm-svn: 245518

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/OptionalTest.cpp b/llvm/unittests/ADT/OptionalTest.cpp
index 92c4eec487a..18b59e31581 100644
--- a/llvm/unittests/ADT/OptionalTest.cpp
+++ b/llvm/unittests/ADT/OptionalTest.cpp
@@ -377,5 +377,18 @@ TEST_F(OptionalTest, MoveGetValueOr) {
 
 #endif // LLVM_HAS_RVALUE_REFERENCE_THIS
 
+TEST_F(OptionalTest, NoneComparison) {
+  Optional<int> o;
+  EXPECT_EQ(o, None);
+  EXPECT_EQ(None, o);
+  EXPECT_FALSE(o != None);
+  EXPECT_FALSE(None != o);
+  o = 3;
+  EXPECT_FALSE(o == None);
+  EXPECT_FALSE(None == o);
+  EXPECT_TRUE(o != None);
+  EXPECT_TRUE(None != o);
+}
+
 } // end anonymous namespace