Allow classic COM interfaces with get_self (#1314)

* Allow classic COM interfaces with get_self Fixes #1312 * Fix mingw builds --------- Co-authored-by: Kenny Kerr <[email protected]>
microsoft · Jun 27, 2023 · 297454e · 297454e
1 parent d3bb275
commit 297454e
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diff --git a/strings/base_implements.h b/strings/base_implements.h
@@ -242,6 +242,12 @@ WINRT_EXPORT namespace winrt
  return &static_cast<impl::produce<D, default_interface<I>>*>(get_abi(from))->shim();
  }
 
+ template <typename D, typename I>
+ D* get_self(com_ptr<I> const& from) noexcept
+ {
+ return static_cast<D*>(static_cast<impl::producer<D, I>*>(from.get()));
+ }
+
  template <typename D, typename I>
  [[deprecated]] D* from_abi(I const& from) noexcept
  {

diff --git a/strings/base_meta.h b/strings/base_meta.h
@@ -13,6 +13,9 @@ WINRT_EXPORT namespace winrt
  template <typename T>
  struct com_ptr;
 
+ template <typename D, typename I>
+ D* get_self(com_ptr<I> const& from) noexcept;
+
  namespace param
  {
  template <typename T>

diff --git a/test/old_tests/UnitTests/interop.cpp b/test/old_tests/UnitTests/interop.cpp
@@ -7,6 +7,10 @@ using namespace Windows::Foundation;
 
 namespace
 {
+ struct IClassicComInterface : ::IUnknown {};
+
+ struct ClassicCom : implements<ClassicCom, IClassicComInterface> {};
+
  struct Stringable : implements<Stringable, IStringable>
  {
  Stringable(std::wstring_view const& value = L"Stringable") : m_value(value)
@@ -30,8 +34,16 @@ namespace
  object->AddRef();
  return object->Release();
  }
+
+ template <typename T>
+ uint32_t get_ref_count(com_ptr<T> const& object)
+ {
+ return get_ref_count(object.get());
+ }
 }
 
+template <> inline constexpr winrt::guid winrt::impl::guid_v<IClassicComInterface>{ 0xc136bb75, 0xbc03, 0x41a6, { 0xa5, 0xdc, 0x5e, 0xfa, 0x67, 0x92, 0x4e, 0xbf } };
+
 TEST_CASE("interop")
 {
  uint32_t const before = get_module_lock();
@@ -108,6 +120,43 @@ TEST_CASE("self")
  REQUIRE(get_ref_count(object) == 1);
  object = nullptr;
 
+ strong = weak.get();
+ REQUIRE(!strong);
+}
+
+TEST_CASE("self_classic_com")
+{
+ com_ptr<ClassicCom> strong = make_self<ClassicCom>();
+
+ REQUIRE(get_ref_count(strong.get()) == 1);
+
+ com_ptr<IClassicComInterface> object = strong.as<IClassicComInterface>();
+
+ REQUIRE(get_ref_count(strong.get()) == 2);
+
+ ClassicCom* ptr = get_self<ClassicCom>(object);
+ REQUIRE(ptr == strong.get());
+
+ REQUIRE(get_ref_count(strong.get()) == 2);
+ strong = nullptr;
+ REQUIRE(get_ref_count(object) == 1);
+
+ strong = get_self<ClassicCom>(object)->get_strong();
+ REQUIRE(get_ref_count(object) == 2);
+ strong = nullptr;
+ REQUIRE(get_ref_count(object) == 1);
+
+ weak_ref<ClassicCom> weak = get_self<ClassicCom>(object)->get_weak();
+ REQUIRE(get_ref_count(object) == 1); // <-- still just one!
+
+ strong = weak.get();
+ REQUIRE(strong);
+ REQUIRE(get_ref_count(object) == 2);
+
+ strong = nullptr;
+ REQUIRE(get_ref_count(object) == 1);
+ object = nullptr;
+
  strong = weak.get();
  REQUIRE(!strong);
 }