bluetooth: mac: Reject requestDevice promise if Mac version is <= 10.9

device/bluetooth/bluetooth_adapter_factory.cc

 // Copyright (c) 2012 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 "device/bluetooth/bluetooth_adapter_factory.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "build/build_config.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 
+#if defined(OS_MACOSX)
+#include "base/mac/mac_util.h"
+#endif
+
 namespace device {
 
 namespace {
 
 // Shared default adapter instance.  We don't want to keep this class around
 // if nobody is using it, so use a WeakPtr and create the object when needed.
 // Since Google C++ Style (and clang's static analyzer) forbids us having
 // exit-time destructors, we use a leaky lazy instance for it.
 base::LazyInstance<base::WeakPtr<BluetoothAdapter> >::Leaky default_adapter =
     LAZY_INSTANCE_INITIALIZER;
@@ skipping 31 matching lines @@
     return true;
 #if defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) || \
     defined(OS_LINUX) || defined(OS_MACOSX)
   return true;
 #else
   return false;
 #endif
 }
 
 // static
+bool BluetoothAdapterFactory::IsLowEnergyAvailable() {
+  DCHECK(IsBluetoothAdapterAvailable());
+
+  // SetAdapterForTesting() may be used to provide a test or mock adapter
+  // instance even on platforms that would otherwise not support it.
+  if (default_adapter.Get())
+    return true;
+#if defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) || \
+    defined(OS_LINUX)
+  return true;
+#elif defined(OS_MACOSX)
+  return base::mac::IsAtLeastOS10_10();
+#endif  // defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) ||
+        // defined(OS_LINUX)
+  return false;

[sdefresne, 2016/10/05 11:08:30]

The above will expand to the following when OS_WIN is defined:

  return true;
  return false;

The Windows compiler warns because the "return false" cannot be reached.

I recommend changing this to the following:

#if defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) || \
     defined(OS_LINUX)
  return true;
#elif defined(OS_MACOSX)
  return base::mac::IsAtLeastOS10_10();
#else
  return false;
#endif  // defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) ||
        // defined(OS_LINUX)

Or if you do want to have an #else, use a local variable (but note that this
will cause a assignment has no effect when building with clang static analyser):

bool is_low_energy_available = false;
#if defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) || \
     defined(OS_LINUX)
  is_low_energy_available = true;
#elif defined(OS_MACOSX)
  is_low_energy_available = base::mac::IsAtLeastOS10_10();
#endif  // defined(OS_ANDROID) || defined(OS_CHROMEOS) || defined(OS_WIN) ||
        // defined(OS_LINUX)
  return is_low_energy_available;

+}
+
+// static
 void BluetoothAdapterFactory::GetAdapter(const AdapterCallback& callback) {
   DCHECK(IsBluetoothAdapterAvailable());
 
 #if defined(OS_WIN) || defined(OS_LINUX) || defined(OS_CHROMEOS)
   if (!default_adapter.Get()) {
     default_adapter.Get() =
         BluetoothAdapter::CreateAdapter(base::Bind(&RunAdapterCallbacks));
     DCHECK(!default_adapter.Get()->IsInitialized());
   }
 
@@ skipping 25 matching lines @@
     scoped_refptr<BluetoothAdapter> adapter) {
   default_adapter.Get() = adapter->GetWeakPtrForTesting();
 }
 
 // static
 bool BluetoothAdapterFactory::HasSharedInstanceForTesting() {
   return default_adapter.Get() != nullptr;
 }
 
 }  // namespace device