From 9553ecfe016845eb8ee704928b4e20be8d5aa04d Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Mon, 5 Aug 2019 21:47:36 +0200
Subject: [PATCH] AK: Optional::operator=(Optional&&) should clear movee's
 has_value bit

We were forgetting to clear m_has_value in the Optional being moved
from when using operator=(Optional&&).
---
 AK/Optional.h             |  1 +
 AK/Tests/Makefile         |  3 +++
 AK/Tests/TestOptional.cpp | 30 ++++++++++++++++++++++++++++++
 3 files changed, 34 insertions(+)
 create mode 100644 AK/Tests/TestOptional.cpp

diff --git a/AK/Optional.h b/AK/Optional.h
index ee6320925e..a73db53bcc 100644
--- a/AK/Optional.h
+++ b/AK/Optional.h
@@ -104,6 +104,7 @@ public:
         ASSERT(m_has_value);
         T released_value = move(value());
         value().~T();
+        m_has_value = false;
         return released_value;
     }
 
diff --git a/AK/Tests/Makefile b/AK/Tests/Makefile
index dc9837e915..30e940dc3a 100644
--- a/AK/Tests/Makefile
+++ b/AK/Tests/Makefile
@@ -48,6 +48,9 @@ TestNonnullRefPtr: TestNonnullRefPtr.o $(SHARED_TEST_OBJS)
 TestRefPtr: TestRefPtr.o $(SHARED_TEST_OBJS)
 	$(PRE_CXX) $(CXX) $(CXXFLAGS) -o $@ TestRefPtr.o $(SHARED_TEST_OBJS)
 
+TestOptional: TestOptional.o $(SHARED_TEST_OBJS)
+	$(PRE_CXX) $(CXX) $(CXXFLAGS) -o $@ TestOptional.o $(SHARED_TEST_OBJS)
+
 clean:
 	rm -f $(SHARED_TEST_OBJS)
 	rm -f $(PROGRAMS)
diff --git a/AK/Tests/TestOptional.cpp b/AK/Tests/TestOptional.cpp
new file mode 100644
index 0000000000..02db877cea
--- /dev/null
+++ b/AK/Tests/TestOptional.cpp
@@ -0,0 +1,30 @@
+#include <AK/TestSuite.h>
+
+#include <AK/AKString.h>
+#include <AK/Optional.h>
+
+TEST_CASE(basic_optional)
+{
+    Optional<int> x;
+    EXPECT_EQ(x.has_value(), false);
+    x = 3;
+    EXPECT_EQ(x.has_value(), true);
+    EXPECT_EQ(x.value(), 3);
+}
+
+TEST_CASE(move_optional)
+{
+    Optional<int> x;
+    EXPECT_EQ(x.has_value(), false);
+    x = 3;
+    EXPECT_EQ(x.has_value(), true);
+    EXPECT_EQ(x.value(), 3);
+
+    Optional<int> y;
+    y = move(x);
+    EXPECT_EQ(y.has_value(), true);
+    EXPECT_EQ(y.value(), 3);
+    EXPECT_EQ(x.has_value(), false);
+}
+
+TEST_MAIN(Optional)