Merge pull request #503 from leapmotion/bug-autopacketallocators

Fix custom allocator invocation

autowiring/auto_arg.h

@@ -112,8 +112,23 @@ template<class T, bool has_default>
 struct auto_arg_ctor_helper<T, has_default, false> {
   static_assert(has_default, "Cannot speculatively construct an output argument of type T, it doesn't have any available constructors");
 
+  template<void* (*)(size_t)>
+  struct fn {};
+
+  template<typename U>
+  static std::shared_ptr<U> Allocate(fn<&U::operator new>*) {
+    return std::shared_ptr<U>(new U);
+  }
+
+  template<typename U>
+  static std::shared_ptr<U> Allocate(...) {
+    return std::make_shared<U>();
+  }
+
   static std::shared_ptr<T> arg(AutoPacket&) {
-    return std::make_shared<T>();
+    // Use make shared, if we can; if static new is present on this type, though, then we have to use
+    // the uglier two-part construction syntax
+    return Allocate<T>(nullptr);
   }
 };
 

src/autowiring/test/AutoFilterConstructRulesTest.cpp

@@ -71,3 +71,44 @@ TEST_F(AutoFilterConstructRulesTest, CanAcceptUndefinedSharedPointerInput) {
   AutoRequired<AcceptsUnnamedExternalClass> auec;
   AutoRequired<AcceptsUnnamedExternalClassSharedPtr> auecsp;
 }
+
+class HasCustomNewFunction {
+public:
+  static bool s_invoked;
+
+  static void* operator new(size_t ncb){
+    s_invoked = true;
+
+    uint8_t* pRetVal = ::new uint8_t[ncb];
+    for (size_t i = 0; i < ncb; i++)
+      pRetVal[i] = (i + 1) * 101;
+    return pRetVal;
+  }
+
+  uint8_t data[128];
+};
+
+bool HasCustomNewFunction::s_invoked = false;
+
+class GeneratesCustomAllocatedType {
+public:
+  void AutoFilter(HasCustomNewFunction&) {}
+};
+
+TEST_F(AutoFilterConstructRulesTest, CorrectlyCallsCustomAllocator) {
+  AutoRequired<AutoPacketFactory> factory;
+  AutoRequired<GeneratesCustomAllocatedType>();
+
+  ASSERT_FALSE(HasCustomNewFunction::s_invoked) << "Custom allocator was invoked prematurely";
+  auto packet = factory->NewPacket();
+  auto* phcnf = packet->GetShared<HasCustomNewFunction>();
+  auto& hcnf = *phcnf;
+  ASSERT_TRUE(phcnf && hcnf) << "Decoration with custom allocator not present on a packet as expected";
+  ASSERT_TRUE(HasCustomNewFunction::s_invoked) << "Custom new allocator was not invoked as expected";
+
+  for (size_t i = 0; i < 128; i++)
+    ASSERT_EQ(
+      static_cast<uint8_t>((i + 1) * 101),
+      hcnf->data[i]
+    ) << "Custom new allocator did not fill space, mismatch at offset " << i;
+}