cppwinrt should not call LoadLibrary anywhere unless new WINRT_REG_FREE define is defined, re-activating regfree behavior

Author: dmachaj

strings/base_activation.h

@@ -18,6 +18,10 @@ namespace winrt::impl
 
     using library_handle = handle_type<library_traits>;
 
+    // This function pointer will be null unless one or more translation units in a binary define WINRT_REG_FREE before
+    // including winrt/base.h.  If that is defined then the overall binary will support regfree COM activation.
+    inline hresult(*reg_free_factory_getter)(param::hstring const&, bool, guid const&, void**) = nullptr;
+
     template <bool isSameInterfaceAsIActivationFactory>
     WINRT_IMPL_NOINLINE hresult get_runtime_activation_factory_impl(param::hstring const& name, winrt::guid const& guid, void** result) noexcept
     {
@@ -30,15 +34,8 @@ namespace winrt::impl
 
         if (hr == impl::error_not_initialized)
         {
-            auto usage = reinterpret_cast<int32_t(__stdcall*)(void** cookie) noexcept>(WINRT_IMPL_GetProcAddress(load_library(L"combase.dll"), "CoIncrementMTAUsage"));
-
-            if (!usage)
-            {
-                return hr;
-            }
-
             void* cookie;
-            usage(&cookie);
+            WINRT_IMPL_CoIncrementMTAUsage(&cookie);
             hr = WINRT_IMPL_RoGetActivationFactory(*(void**)(&name), guid, result);
         }
 
@@ -47,6 +44,17 @@ namespace winrt::impl
             return 0;
         }
 
+        if (reg_free_factory_getter)
+        {
+            return reg_free_factory_getter(name, isSameInterfaceAsIActivationFactory, guid, result);
+        }
+
+        return hr;
+    }
+
+#ifdef WINRT_REG_FREE
+    WINRT_IMPL_NOINLINE hresult reg_free_get_activation_factory(param::hstring const& name, bool isSameInterfaceAsIActivationFactory, winrt::guid const& guid, void** result) noexcept
+    {
         com_ptr<IErrorInfo> error_info;
         WINRT_IMPL_GetErrorInfo(0, error_info.put_void());
 
@@ -79,7 +87,7 @@ namespace winrt::impl
                 continue;
             }
 
-            if constexpr (isSameInterfaceAsIActivationFactory)
+            if (isSameInterfaceAsIActivationFactory)
             {
                 *result = library_factory.detach();
                 library.detach();
@@ -93,9 +101,18 @@ namespace winrt::impl
         }
 
         WINRT_IMPL_SetErrorInfo(0, error_info.get());
-        return hr;
+        return error_class_not_registered;
     }
 
+    // This file has been compiled by a translation unit with WINRT_REG_FREE defined.  Fill in the reg_free_factory_getter function
+    // pointer so that regfree behavior is activated.
+    inline unsigned int reg_free_init = []() {
+        reg_free_factory_getter = reg_free_get_activation_factory;
+        return 0U;
+    }();
+
+#endif // WINRT_REG_FREE
+
     template <typename Interface>
     hresult get_runtime_activation_factory(param::hstring const& name, void** result) noexcept
     {

strings/base_agile_ref.h

@@ -71,10 +71,12 @@ namespace winrt::impl
 
     using update_module_lock = module_lock_updater<true>;
 
+#ifdef WINRT_REG_FREE
     inline void* load_library(wchar_t const* library) noexcept
     {
         return WINRT_IMPL_LoadLibraryExW(library, nullptr, 0x00001000 /* LOAD_LIBRARY_SEARCH_DEFAULT_DIRS */);
     }
+#endif // WINRT_REG_FREE
 
     inline hresult get_agile_reference(winrt::guid const& iid, void* object, void** reference) noexcept
     {

strings/base_extern.h

@@ -35,14 +35,17 @@ extern "C"
     int32_t __stdcall WINRT_IMPL_GetRestrictedErrorInfo(void**) noexcept WINRT_IMPL_LINK(GetRestrictedErrorInfo, 4);
     int32_t __stdcall WINRT_IMPL_SetRestrictedErrorInfo(void*) noexcept WINRT_IMPL_LINK(SetRestrictedErrorInfo, 4);
 
+#ifdef WINRT_REG_FREE
     void* __stdcall WINRT_IMPL_LoadLibraryExW(wchar_t const* name, void* unused, uint32_t flags) noexcept WINRT_IMPL_LINK(LoadLibraryExW, 12);
+#endif // WINRT_REG_FREE
     int32_t __stdcall WINRT_IMPL_FreeLibrary(void* library) noexcept WINRT_IMPL_LINK(FreeLibrary, 4);
     void* __stdcall WINRT_IMPL_GetProcAddress(void* library, char const* name) noexcept WINRT_IMPL_LINK(GetProcAddress, 8);
 
     int32_t __stdcall WINRT_IMPL_SetErrorInfo(uint32_t reserved, void* info) noexcept WINRT_IMPL_LINK(SetErrorInfo, 8);
     int32_t __stdcall WINRT_IMPL_GetErrorInfo(uint32_t reserved, void** info) noexcept WINRT_IMPL_LINK(GetErrorInfo, 8);
     int32_t __stdcall WINRT_IMPL_CoInitializeEx(void*, uint32_t type) noexcept WINRT_IMPL_LINK(CoInitializeEx, 8);
     void    __stdcall WINRT_IMPL_CoUninitialize() noexcept WINRT_IMPL_LINK(CoUninitialize, 0);
+    int32_t __stdcall WINRT_IMPL_CoIncrementMTAUsage(void** cookie) noexcept WINRT_IMPL_LINK(CoIncrementMTAUsage, 4);
 
     int32_t  __stdcall WINRT_IMPL_CoCreateFreeThreadedMarshaler(void* outer, void** marshaler) noexcept WINRT_IMPL_LINK(CoCreateFreeThreadedMarshaler, 8);
     int32_t  __stdcall WINRT_IMPL_CoCreateInstance(winrt::guid const& clsid, void* outer, uint32_t context, winrt::guid const& iid, void** object) noexcept WINRT_IMPL_LINK(CoCreateInstance, 20);

test/old_tests/UnitTests/pch.h

@@ -1,6 +1,7 @@
 #pragma once
 
-#define WIN32_LEAN_AND_MEAN 
+#define WIN32_LEAN_AND_MEAN
+#define WINRT_REG_FREE
 #define WINRT_NATVIS
 #define _SILENCE_CXX17_UNCAUGHT_EXCEPTION_DEPRECATION_WARNING
 

test/test/pch.h

@@ -5,6 +5,7 @@
 #include "mingw_com_support.h"
 
 #define WINRT_LEAN_AND_MEAN
+#define WINRT_REG_FREE
 #include <unknwn.h>
 #include "winrt/Windows.Foundation.Collections.h"
 #include "winrt/Windows.Foundation.Numerics.h"

test/test_fast/pch.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#define WINRT_REG_FREE
 #include "catch.hpp"
 #include "winrt/Windows.Foundation.Collections.h"
 

test/test_slow/pch.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#define WINRT_REG_FREE
 #include "catch.hpp"
 #include "winrt/Windows.Foundation.Collections.h"