Precalculate pinterface guids for known generic instantiations

CMakeLists.txt

@@ -184,7 +184,7 @@ if(EXTERNAL_WINMD_INCLUDE_DIR STREQUAL "")
     include(ExternalProject)
     ExternalProject_Add(winmd
         GIT_REPOSITORY https://github.com/microsoft/winmd.git
-        GIT_TAG 0f1eae3bfa63fa2ba3c2912cbfe72a01db94cc5a
+        GIT_TAG 1.0.260529.3
         CONFIGURE_COMMAND ""
         BUILD_COMMAND ""
         INSTALL_COMMAND ""

cppwinrt/code_writers.h

@@ -206,6 +206,23 @@ namespace cppwinrt
         return { w, write_close_namespace };
     }
 
+    [[nodiscard]] static finish_with wrap_extern_cpp_impl_namespace(writer& w)
+    {
+        w.write(R"(
+extern "C++"
+{
+namespace winrt::impl
+{
+)");
+
+        return { w, [](writer& w) {
+            w.write(R"(
+} // winrt::impl
+} // extern "C++"
+)");
+        }};
+    }
+
     [[nodiscard]] static finish_with wrap_std_namespace(writer& w)
     {
         w.write(R"(namespace std
@@ -537,6 +554,58 @@ namespace cppwinrt
         }
     }
 
+    static std::string make_pinterface_guard(std::string_view const& cpp_name)
+    {
+        std::string guard = "WINRT_IMPL_PINTERFACE_GUID_";
+        guard.reserve(guard.size() + cpp_name.size());
+        for (char c : cpp_name)
+        {
+            if (c == ':' || c == '<' || c == '>' || c == ',' || c == ' ')
+                guard += '_';
+            else
+                guard += c;
+        }
+        return guard;
+    }
+
+    static void write_generic_inst_specializations(writer& w, std::map<std::string, generic_inst_info> const& instantiations)
+    {
+        if (instantiations.empty())
+        {
+            return;
+        }
+
+        // This block is self-contained (written outside any open namespace).
+        // extern "C++" attaches specializations to the global module so identical
+        // specializations across modules merge rather than collide.
+        // #ifndef guards prevent redefinition within a single TU (SCC-consolidated modules).
+        auto wrap_ns = wrap_extern_cpp_impl_namespace(w);
+
+        for (auto&& [cpp_name, info] : instantiations)
+        {
+            auto guard = make_pinterface_guard(cpp_name);
+            {
+                auto wrap_guard = wrap_ifndef(w, guard);
+                w.write("#define %\n", guard);
+                w.write("    template <> struct pinterface_guid<%>\n", cpp_name);
+                w.write("    {\n");
+                w.write("        static constexpr bool precomputed = true;\n");
+                w.write("        static constexpr guid value{ ");
+                auto& g = info.guid;
+                w.write_printf("0x%08X,0x%04X,0x%04X,{ 0x%02X,0x%02X,0x%02X,0x%02X,0x%02X,0x%02X,0x%02X,0x%02X }",
+                    g.Data1, g.Data2, g.Data3,
+                    g.Data4[0], g.Data4[1], g.Data4[2], g.Data4[3],
+                    g.Data4[4], g.Data4[5], g.Data4[6], g.Data4[7]);
+                w.write(" }; // ");
+                w.write_printf("%08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X\n",
+                    g.Data1, g.Data2, g.Data3,
+                    g.Data4[0], g.Data4[1], g.Data4[2], g.Data4[3],
+                    g.Data4[4], g.Data4[5], g.Data4[6], g.Data4[7]);
+                w.write("    };\n");
+            }
+        }
+    }
+
     static void write_struct_category(writer& w, TypeDef const& type)
     {
         auto format = R"(    template <> struct category<%>{ using type = struct_category<%>; };

cppwinrt/cppwinrt.vcxproj

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="..\packages\Microsoft.Windows.WinMD.1.0.210629.2\build\native\Microsoft.Windows.WinMD.props" Condition="Exists('..\packages\Microsoft.Windows.WinMD.1.0.210629.2\build\native\Microsoft.Windows.WinMD.props')" />
+  <Import Project="..\packages\Microsoft.Windows.WinMD.1.0.260529.3\build\native\Microsoft.Windows.WinMD.props" Condition="Exists('..\packages\Microsoft.Windows.WinMD.1.0.260529.3\build\native\Microsoft.Windows.WinMD.props')" />
   <ItemGroup Label="ProjectConfigurations">
     <ProjectConfiguration Include="Debug|ARM64">
       <Configuration>Debug</Configuration>
@@ -309,6 +309,6 @@
     <PropertyGroup>
       <ErrorText>This project references NuGet package(s) that are missing on this computer. Use NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
     </PropertyGroup>
-    <Error Condition="!Exists('..\packages\Microsoft.Windows.WinMD.1.0.210629.2\build\native\Microsoft.Windows.WinMD.props')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\Microsoft.Windows.WinMD.1.0.210629.2\build\native\Microsoft.Windows.WinMD.props'))" />
+    <Error Condition="!Exists('..\packages\Microsoft.Windows.WinMD.1.0.260529.3\build\native\Microsoft.Windows.WinMD.props')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\Microsoft.Windows.WinMD.1.0.260529.3\build\native\Microsoft.Windows.WinMD.props'))" />
   </Target>
 </Project>

cppwinrt/file_writers.h

@@ -116,12 +116,32 @@ namespace cppwinrt
             w.write_each<write_guid>(members.interfaces);
             w.write_each<write_guid>(members.delegates);
             w.write_each<write_default_interface>(members.classes);
+
             w.write_each<write_interface_abi>(members.interfaces);
             w.write_each<write_delegate_abi>(members.delegates);
             w.write_each<write_consume>(members.interfaces);
             w.write_each<write_struct_abi>(members.structs);
         }
 
+        // Emit pinterface_guid specializations AFTER the wrap_impl_namespace block
+        // so they don't break the WINRT_EXPORT attribute on subsequent declarations.
+        // The function writes a self-contained extern "C++" block.
+        {
+            std::map<std::string, generic_inst_info> instantiations;
+            collect_generic_instantiations(w, members, instantiations);
+
+            // For Windows.Foundation, also inject well-known IReference<T>/IReferenceArray<T>
+            // specializations for standard primitive and struct types. These ensure that
+            // consumers who only include Windows.Foundation.h get precomputed GUIDs for
+            // boxing types, without depending on other namespace headers.
+            if (ns == "Windows.Foundation")
+            {
+                add_well_known_ireference_instantiations(w, members, instantiations);
+            }
+
+            write_generic_inst_specializations(w, instantiations);
+        }
+
         write_close_file_guard(w);
         w.swap();
         write_preamble(w);