base::Optional operator bool doesn't convert to bool.

base/optional_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/optional.h"
 
 #include <set>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 423 matching lines @@
   EXPECT_EQ(0.1f, *Optional<float>(0.1f));
   EXPECT_EQ(std::string("foo"), *Optional<std::string>("foo"));
   EXPECT_TRUE(TestObject(3, 0.1) == *Optional<TestObject>(TestObject(3, 0.1)));
 }
 
 TEST(OptionalTest, OperatorArrow) {
   Optional<TestObject> a(TestObject(3, 0.1));
   EXPECT_EQ(a->foo(), 3);
 }
 
+TEST(OptionalTest, OperatorBool) {
+  {
+    Optional<TestObject> a;
+    EXPECT_EQ(static_cast<bool>(a), false);  // works.
+  }
+
+  {
+    Optional<TestObject> a;
+    bool b = !!a;  // works.
+    EXPECT_EQ(b, false);
+  }
+
+  {
+    Optional<TestObject> a;
+    bool b = a;
+    // error: no viable conversion from
+    // 'Optional<base::(anonymous namespace)::TestObject>' to 'bool'
+    EXPECT_EQ(b, false);
+  }
+
+  // More to add here... testing true etc.
+}
+
 TEST(OptionalTest, Value_rvalue) {
   EXPECT_EQ(0.1f, Optional<float>(0.1f).value());
   EXPECT_EQ(std::string("foo"), Optional<std::string>("foo").value());
   EXPECT_TRUE(TestObject(3, 0.1) ==
               Optional<TestObject>(TestObject(3, 0.1)).value());
 }
 
 TEST(OptionalTest, ValueOr) {
   {
     Optional<float> a;
@@ skipping 883 matching lines @@
 
 TEST(OptionalTest, Reset_NoOp) {
   Optional<int> a;
   EXPECT_FALSE(a.has_value());
 
   a.reset();
   EXPECT_FALSE(a.has_value());
 }
 
 }  // namespace base