Deducing this for delegates

.github/workflows/ci.yml

@@ -102,7 +102,7 @@ jobs:
         compiler: [MSVC, clang-cl]
         arch: [x86, x64, arm64]
         config: [Debug, Release]
-        test_exe: [test, test_cpp20, test_cpp20_no_sourcelocation, test_fast, test_slow, test_old, test_module_lock_custom, test_module_lock_none]
+        test_exe: [test, test_cpp20, test_cpp20_no_sourcelocation, test_cpp23, test_fast, test_slow, test_old, test_module_lock_custom, test_module_lock_none]
         exclude:
           - arch: arm64
             config: Debug

CMakeLists.txt

@@ -13,8 +13,8 @@ project(cppwinrt LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED True)
 
-set(CPPWINRT_BUILD_VERSION "2.3.4.5" CACHE STRING "The version string used for cppwinrt.")
-if(CPPWINRT_BUILD_VERSION STREQUAL "2.3.4.5" OR CPPWINRT_BUILD_VERSION STREQUAL "0.0.0.0")
+set(CPPWINRT_BUILD_VERSION "1.2.3.4" CACHE STRING "The version string used for cppwinrt.")
+if(CPPWINRT_BUILD_VERSION STREQUAL "1.2.3.4" OR CPPWINRT_BUILD_VERSION STREQUAL "0.0.0.0")
     message(WARNING "CPPWINRT_BUILD_VERSION has been set to a dummy version string. Do not use in production!")
 endif()
 message(STATUS "Using version string: ${CPPWINRT_BUILD_VERSION}")

Directory.Build.Props

@@ -37,7 +37,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <CppWinRTBuildVersion Condition="'$(CppWinRTBuildVersion)'==''">2.3.4.5</CppWinRTBuildVersion>
+    <CppWinRTBuildVersion Condition="'$(CppWinRTBuildVersion)'==''">1.2.3.4</CppWinRTBuildVersion>
     <CppWinRTPlatform>$(Platform)</CppWinRTPlatform>
     <CppWinRTPlatform Condition="'$(Platform)'=='Win32'">x86</CppWinRTPlatform>
     <OutDir>$(SolutionDir)_build\$(CppWinRTPlatform)\$(Configuration)\</OutDir>

build_test_all.cmd

@@ -45,6 +45,7 @@ call msbuild /p:Configuration=%target_configuration%,Platform=%target_platform%,
 call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test
 call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test_cpp20
 call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test_cpp20_no_sourcelocation
+call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test_cpp23
 call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test_fast
 call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test_slow
 call msbuild /m /p:Configuration=%target_configuration%,Platform=%target_platform%,CppWinRTBuildVersion=%target_version% cppwinrt.slnx /t:test\test_module_lock_custom

cppwinrt.slnx

@@ -47,6 +47,10 @@
       <BuildDependency Project="cppwinrt/cppwinrt.vcxproj" />
       <BuildDependency Project="test/test_component/test_component.vcxproj" />
     </Project>
+    <Project Path="test/test_cpp23/test_cpp23.vcxproj">
+      <BuildDependency Project="cppwinrt/cppwinrt.vcxproj" />
+      <BuildDependency Project="test/test_component/test_component.vcxproj" />
+    </Project>
     <Project Path="test/test_cpp20_no_sourcelocation/test_cpp20_no_sourcelocation.vcxproj">
       <BuildDependency Project="cppwinrt/cppwinrt.vcxproj" />
       <BuildDependency Project="test/test_component/test_component.vcxproj" />

cppwinrt/code_writers.h

@@ -2646,7 +2646,7 @@ struct WINRT_IMPL_EMPTY_BASES produce_dispatch_to_overridable<T, D, %>
             type,
             bind<write_abi_params>(signature),
             bind<write_produce_cleanup>(signature),
-            bind<write_produce_upcall>("(*this)", signature));
+            bind<write_produce_upcall>("static_cast<H&>(*this)", signature));
     }
 
     static void write_delegate_definition(writer& w, TypeDef const& type)

run_tests.cmd

@@ -11,6 +11,7 @@ if "%target_configuration%"=="" set target_configuration=Debug
 call :run_test test
 call :run_test test_cpp20
 call :run_test test_cpp20_no_sourcelocation
+call :run_test test_cpp23
 call :run_test test_fast
 call :run_test test_slow
 call :run_test test_old

strings/base_delegate.h

@@ -125,11 +125,11 @@ WINRT_EXPORT namespace winrt::impl
         {
             if constexpr (std::is_void_v<R>)
             {
-                (*this)(args...);
+                static_cast<H&>(*this)(args...);
             }
             else
             {
-                return (*this)(args...);
+                return static_cast<H&>(*this)(args...);
             }
         }
 

test/CMakeLists.txt

@@ -107,6 +107,7 @@ set(SKIP_LARGE_PCH FALSE CACHE BOOL "Skip building large precompiled headers.")
 add_subdirectory(test)
 add_subdirectory(test_cpp20)
 add_subdirectory(test_cpp20_no_sourcelocation)
+add_subdirectory(test_cpp23)
 
 if(HAS_WINDOWSNUMERICS)
     add_subdirectory(old_tests)

test/catch.hpp

@@ -677,12 +677,12 @@ namespace Catch {
     auto operator += ( std::string& lhs, StringRef const& sr ) -> std::string&;
     auto operator << ( std::ostream& os, StringRef const& sr ) -> std::ostream&;
 
-    constexpr auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
+    constexpr auto operator ""_sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
         return StringRef( rawChars, size );
     }
 } // namespace Catch
 
-constexpr auto operator "" _catch_sr( char const* rawChars, std::size_t size ) noexcept -> Catch::StringRef {
+constexpr auto operator ""_catch_sr( char const* rawChars, std::size_t size ) noexcept -> Catch::StringRef {
     return Catch::StringRef( rawChars, size );
 }
 
@@ -3177,8 +3177,8 @@ namespace Detail {
 } // end namespace Detail
 
 namespace literals {
-    Detail::Approx operator "" _a(long double val);
-    Detail::Approx operator "" _a(unsigned long long val);
+    Detail::Approx operator ""_a(long double val);
+    Detail::Approx operator ""_a(unsigned long long val);
 } // end namespace literals
 
 template<>
@@ -7922,10 +7922,10 @@ namespace Detail {
 } // end namespace Detail
 
 namespace literals {
-    Detail::Approx operator "" _a(long double val) {
+    Detail::Approx operator ""_a(long double val) {
         return Detail::Approx(val);
     }
-    Detail::Approx operator "" _a(unsigned long long val) {
+    Detail::Approx operator ""_a(unsigned long long val) {
         return Detail::Approx(val);
     }
 } // end namespace literals

test/test_cpp20/test_cpp20.vcxproj

@@ -108,14 +108,6 @@
       <EnableCOMDATFolding>true</EnableCOMDATFolding>
       <OptimizeReferences>true</OptimizeReferences>
     </Link>
-    <PreBuildEvent>
-      <Command>
-      </Command>
-    </PreBuildEvent>
-    <PostBuildEvent>
-      <Command>
-      </Command>
-    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <ClCompile>
@@ -130,14 +122,6 @@
     <Link>
       <SubSystem>Console</SubSystem>
     </Link>
-    <PreBuildEvent>
-      <Command>
-      </Command>
-    </PreBuildEvent>
-    <PostBuildEvent>
-      <Command>
-      </Command>
-    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">
     <ClCompile>
@@ -152,14 +136,6 @@
     <Link>
       <SubSystem>Console</SubSystem>
     </Link>
-    <PreBuildEvent>
-      <Command>
-      </Command>
-    </PreBuildEvent>
-    <PostBuildEvent>
-      <Command>
-      </Command>
-    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
     <ClCompile>
@@ -174,14 +150,6 @@
     <Link>
       <SubSystem>Console</SubSystem>
     </Link>
-    <PreBuildEvent>
-      <Command>
-      </Command>
-    </PreBuildEvent>
-    <PostBuildEvent>
-      <Command>
-      </Command>
-    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <ClCompile>
@@ -200,14 +168,6 @@
       <EnableCOMDATFolding>true</EnableCOMDATFolding>
       <OptimizeReferences>true</OptimizeReferences>
     </Link>
-    <PreBuildEvent>
-      <Command>
-      </Command>
-    </PreBuildEvent>
-    <PostBuildEvent>
-      <Command>
-      </Command>
-    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">
     <ClCompile>
@@ -226,14 +186,6 @@
       <EnableCOMDATFolding>true</EnableCOMDATFolding>
       <OptimizeReferences>true</OptimizeReferences>
     </Link>
-    <PreBuildEvent>
-      <Command>
-      </Command>
-    </PreBuildEvent>
-    <PostBuildEvent>
-      <Command>
-      </Command>
-    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClInclude Include="pch.h" />

test/test_cpp23/CMakeLists.txt

@@ -0,0 +1,23 @@
+set(CMAKE_CXX_STANDARD 23)
+
+file(GLOB TEST_SRCS
+    LIST_DIRECTORIES false
+    CONFIGURE_DEPENDS
+    *.cpp
+)
+list(FILTER TEST_SRCS EXCLUDE REGEX "/(main|pch)\\.cpp")
+
+add_executable(test_cpp23 main.cpp ${TEST_SRCS})
+
+target_precompile_headers(test_cpp23 PRIVATE pch.h)
+set_source_files_properties(
+    main.cpp
+    PROPERTIES SKIP_PRECOMPILE_HEADERS true
+)
+
+add_dependencies(test_cpp23 build-cppwinrt-projection)
+
+add_test(
+    NAME test_cpp23
+    COMMAND "$<TARGET_FILE:test_cpp23>" ${TEST_COLOR_ARG}
+)

test/test_cpp23/delegate_deducing_this.cpp

@@ -0,0 +1,129 @@
+#include "pch.h"
+
+using namespace winrt;
+using namespace Windows::Foundation::Collections;
+
+#if defined(__cpp_explicit_this_parameter) && __cpp_explicit_this_parameter >= 202110L
+
+TEST_CASE("delegate")
+{
+    // <>
+    {
+        bool invoked = false;
+        delegate<> d = [&](this auto) { invoked = true; };
+        d();
+        REQUIRE(invoked);
+    }
+
+    // <int>
+    {
+        int result = 0;
+        delegate<int> d = [&](this auto, int a) { result = a; };
+        d(123);
+        REQUIRE(result == 123);
+    }
+
+    // <int,int>
+    {
+        int result = 0;
+        delegate<int, int> d = [&](this auto, int a, int b) { result = a + b; };
+        d(4,5);
+        REQUIRE(result == 9);
+    }
+
+    // void()
+    {
+        bool invoked = false;
+        delegate<void()> d = [&](this auto) { invoked = true; };
+        d();
+        REQUIRE(invoked);
+    }
+
+    // void(int)
+    {
+        int result = 0;
+        delegate<void(int)> d = [&](this auto, int a) { result = a; };
+        d(123);
+        REQUIRE(result == 123);
+    }
+
+    // void(int,int)
+    {
+        int result = 0;
+        delegate<void(int,int)> d = [&](this auto, int a, int b) { result = a + b; };
+        d(4, 5);
+        REQUIRE(result == 9);
+    }
+
+    // int()
+    {
+        delegate<int()> d = [](this auto) { return 123; };
+        REQUIRE(d() == 123);
+    }
+
+    // int(int)
+    {
+        delegate<int(int)> d = [](this auto, int a) { return a; };
+        REQUIRE(d(123) == 123);
+    }
+
+    // int(int,int)
+    {
+        delegate<int(int, int)> d = [](this auto, int a, int b) { return a + b; };
+        REQUIRE(d(4, 5) == 9);
+    }
+}
+
+TEST_CASE("typedeventhandler")
+{
+    using Handler = winrt::Windows::Foundation::TypedEventHandler<int, int>;
+
+    int called{};
+    int sum{};
+
+    Handler handler = [&called, &sum](this auto, int sender, int args)
+    {
+        ++called;
+        sum = sender + args;
+    };
+
+    handler(1, 2);
+
+    REQUIRE(called == 1);
+    REQUIRE(sum == 3);
+}
+
+#if !(defined(_M_IX86) && !defined(_M_X64) && defined(__clang__))
+// Clang 20 target x86 generates incorrect code for this test.
+// In observed_sender ctor (#1), this = X; in assignment operator (#2), this = X+16 (bytes).
+// FIXME: Enable the test after Clang is fixed
+TEST_CASE("observablevector_vectorchanged")
+{
+    IObservableVector<int> vector = single_threaded_observable_vector<int>();
+
+    int called{};
+    IObservableVector<int> observed_sender{ nullptr }; // #1
+    CollectionChange change{};
+    uint32_t index{};
+
+    auto token = vector.VectorChanged([&](this auto, IObservableVector<int> sender, IVectorChangedEventArgs args)
+        {
+            ++called;
+            observed_sender = sender; // #2
+            change = args.CollectionChange();
+            index = args.Index();
+        });
+
+    vector.Append(123);
+
+    REQUIRE(called == 1);
+    REQUIRE(observed_sender == vector);
+    REQUIRE(change == CollectionChange::ItemInserted);
+    REQUIRE(index == 0);
+
+    vector.VectorChanged(token);
+}
+
+#endif
+
+#endif