Check for STA and NA when deciding to call directly or post a callback. (#459)

Author: jlaanstra

strings/base_coroutine_foundation.h

@@ -88,7 +88,7 @@ namespace winrt::impl
 
         void await_suspend(std::experimental::coroutine_handle<> handle) const
         {
-            async.Completed([handle, context = impl::sta_apartment_context()](auto&& ...)
+            async.Completed([handle, context = impl::apartment_context()](auto&& ...)
             {
                 impl::resume_apartment(context, handle);
             });

strings/base_coroutine_threadpool.h

@@ -21,9 +21,16 @@ namespace winrt::impl
         return (0 == WINRT_CoGetApartmentType(&aptType, &aptTypeQualifier)) && ((aptType == 0 /*APTTYPE_STA*/) || (aptType == 3 /*APTTYPE_MAINSTA*/));
     }
 
-    inline auto sta_apartment_context()
+    inline bool requires_apartment_context() noexcept
     {
-        return is_sta() ? capture<IContextCallback>(WINRT_CoGetObjectContext) : nullptr;
+        int32_t aptType;
+        int32_t aptTypeQualifier;
+        return (0 == WINRT_CoGetApartmentType(&aptType, &aptTypeQualifier)) && ((aptType == 0 /*APTTYPE_STA*/) || (aptType == 2 /*APTTYPE_NA*/) || (aptType == 3 /*APTTYPE_MAINSTA*/));
+    }
+
+    inline auto apartment_context()
+    {
+        return requires_apartment_context() ? capture<IContextCallback>(WINRT_CoGetObjectContext) : nullptr;
     }
 
     inline int32_t __stdcall resume_apartment_callback(com_callback_args* args) noexcept
@@ -32,18 +39,18 @@ namespace winrt::impl
         return 0;
     };
 
-    inline auto resume_apartment(com_ptr<IContextCallback> const& sta_context, std::experimental::coroutine_handle<> handle)
+    inline auto resume_apartment(com_ptr<IContextCallback> const& context, std::experimental::coroutine_handle<> handle)
     {
-        if (sta_context)
+        if (context)
         {
             com_callback_args args{};
             args.data = handle.address();
 
-            check_hresult(sta_context->ContextCallback(resume_apartment_callback, &args, guid_of<ICallbackWithNoReentrancyToApplicationSTA>(), 5, nullptr));
+            check_hresult(context->ContextCallback(resume_apartment_callback, &args, guid_of<ICallbackWithNoReentrancyToApplicationSTA>(), 5, nullptr));
         }
         else
         {
-            if (is_sta())
+            if (requires_apartment_context())
             {
                 resume_background(handle);
             }
@@ -284,10 +291,10 @@ WINRT_EXPORT namespace winrt
 
         void await_suspend(std::experimental::coroutine_handle<> handle) const
         {
-            impl::resume_apartment(sta_context, handle);
+            impl::resume_apartment(context, handle);
         }
 
-        com_ptr<impl::IContextCallback> sta_context = impl::sta_apartment_context();
+        com_ptr<impl::IContextCallback> context = impl::apartment_context();
     };
 
     [[nodiscard]] inline auto resume_after(Windows::Foundation::TimeSpan duration) noexcept