Test component project is building. Checkpoint with some documentation added.

Author: DefaultRyan

cppwinrt/code_writers.h

@@ -37,7 +37,19 @@ namespace cppwinrt
 
     static void write_version_assert(writer& w)
     {
+        // When WINRT_IMPL_SKIP_INCLUDES is defined, base.h is already available
+        // from the imported winrt module. However, macros don't cross module
+        // boundaries, so we include a lightweight header with just the macros.
+        auto format_guard = R"(#ifdef WINRT_IMPL_SKIP_INCLUDES
+#include "winrt/base_macros.h"
+#else
+)";
+        auto format_end = R"(#endif
+)";
+        w.write(format_guard);
         w.write_root_include("base");
+        w.write(format_end);
+
         auto format = R"(static_assert(winrt::check_version(CPPWINRT_VERSION, "%"), "Mismatched C++/WinRT headers.");
 #define CPPWINRT_VERSION "%"
 )";
@@ -137,7 +149,7 @@ namespace cppwinrt
 
         if (found != c.namespaces().end() && has_projected_types(found->second))
         {
-            w.write_root_include(parent);
+            w.write_root_include_guarded(parent);
         }
         else
         {

cppwinrt/component_writers.h

@@ -136,7 +136,14 @@ namespace cppwinrt
 
     static void write_module_g_cpp(writer& w, std::vector<TypeDef> const& classes)
     {
-        w.write_root_include("base");
+        if (settings.component_module)
+        {
+            w.write("import std;\nimport winrt;\n");
+        }
+        else
+        {
+            w.write_root_include("base");
+        }
         auto format = R"(%
 bool __stdcall %_can_unload_now() noexcept
 {
@@ -397,6 +404,14 @@ catch (...) { return winrt::to_hresult(); }
             return;
         }
 
+        // In module mode, the constructor/static definitions are already exported
+        // from the winrt module (via the namespace header folded into winrt.ixx).
+        // Only the winrt_make_* factory function above is needed.
+        if (settings.component_module)
+        {
+            return;
+        }
+
         auto wrap_type = wrap_type_namespace(w, type_namespace);
 
         for (auto&&[factory_name, factory] : get_factories(w, type))

cppwinrt/file_writers.h

@@ -46,6 +46,57 @@ namespace cppwinrt
         w.flush_to_file(settings.output_folder + "winrt/base.h");
     }
 
+    // Lightweight header containing only the preprocessor macros needed by
+    // generated namespace headers. Used when WINRT_IMPL_SKIP_INCLUDES is
+    // defined (i.e., consuming component headers after 'import winrt;').
+    // Macros don't cross module boundaries, so this provides the macros
+    // that base.h would normally supply.
+    static void write_base_macros_h()
+    {
+        writer w;
+        write_preamble(w);
+        w.write(R"(#pragma once
+
+// This header provides the preprocessor macros needed by generated C++/WinRT
+// headers when the full base.h is not #included (e.g., when using 'import winrt;').
+// Macros are not exported across C++20 module boundaries, so this lightweight
+// header must be included textually.
+
+#ifndef CPPWINRT_VERSION
+#define CPPWINRT_VERSION "%"
+#endif
+
+#ifndef WINRT_EXPORT
+#define WINRT_EXPORT
+#endif
+
+#if defined(_MSC_VER)
+#define WINRT_IMPL_EMPTY_BASES __declspec(empty_bases)
+#else
+#define WINRT_IMPL_EMPTY_BASES
+#endif
+
+#if defined(_MSC_VER)
+#define WINRT_IMPL_NOVTABLE __declspec(novtable)
+#else
+#define WINRT_IMPL_NOVTABLE
+#endif
+
+#if defined(__clang__) && defined(__has_attribute)
+#if __has_attribute(__lto_visibility_public__)
+#define WINRT_IMPL_PUBLIC __attribute__((lto_visibility_public))
+#else
+#define WINRT_IMPL_PUBLIC
+#endif
+#else
+#define WINRT_IMPL_PUBLIC
+#endif
+
+#define WINRT_IMPL_ABI_DECL WINRT_IMPL_NOVTABLE WINRT_IMPL_PUBLIC
+)", CPPWINRT_VERSION_STRING);
+        w.flush_to_file(settings.output_folder + "winrt/base_macros.h");
+    }
+
     static void write_fast_forward_h(std::vector<TypeDef> const& classes)
     {
         writer w;
@@ -139,7 +190,7 @@ namespace cppwinrt
 
         for (auto&& depends : w.depends)
         {
-            w.write_depends(depends.first, '0');
+            w.write_depends_guarded(depends.first, '0');
         }
 
         w.write_depends(w.type_namespace, '0');
@@ -169,7 +220,7 @@ namespace cppwinrt
 
         for (auto&& depends : w.depends)
         {
-            w.write_depends(depends.first, impl);
+            w.write_depends_guarded(depends.first, impl);
         }
 
         w.write_depends(w.type_namespace, '1');
@@ -224,7 +275,7 @@ namespace cppwinrt
 
         for (auto&& depends : w.depends)
         {
-            w.write_depends(depends.first, '2');
+            w.write_depends_guarded(depends.first, '2');
         }
 
         w.write_depends(w.type_namespace, '2');
@@ -250,9 +301,22 @@ namespace cppwinrt
         write_preamble(w);
         write_include_guard(w);
 
-        for (auto&& depends : w.depends)
+        if (settings.component_module)
+        {
+            // In module mode, both SDK and component types are available from
+            // 'import winrt;' (the component projection is folded into the
+            // winrt.ixx module). Only macros need a textual include since
+            // they don't cross module boundaries.
+            w.write("#include \"winrt/base_macros.h\"\n");
+            w.write("import std;\n");
+            w.write("import winrt;\n");
+        }
+        else
         {
-            w.write_depends(depends.first);
+            for (auto&& depends : w.depends)
+            {
+                w.write_depends(depends.first);
+            }
         }
 
         auto filename = settings.output_folder + get_generated_component_filename(type) + ".g.h";

cppwinrt/main.cpp

@@ -39,6 +39,7 @@ namespace cppwinrt
         { "fastabi", 0, 0 }, // Enable support for the Fast ABI
         { "ignore_velocity", 0, 0 }, // Ignore feature staging metadata and always include implementations
         { "synchronous", 0, 0 }, // Instructs cppwinrt to run on a single thread to avoid file system issues in batch builds
+        { "module", 0, 0, {}, "Generate component files using 'import winrt;' instead of #include" },
     };
 
     static void print_usage(writer& w)
@@ -172,6 +173,13 @@ R"(  local               Local ^%WinDir^%\System32\WinMetadata folder
             settings.component_lib = args.value("library", "winrt");
             settings.component_opt = args.exists("optimize");
             settings.component_ignore_velocity = args.exists("ignore_velocity");
+            settings.component_module = args.exists("module");
+
+            if (settings.component_module)
+            {
+                // Module mode disables the PCH include in generated files
+                settings.component_pch.clear();
+            }
 
             if (settings.component_pch == ".")
             {
@@ -373,6 +381,7 @@ R"(  local               Local ^%WinDir^%\System32\WinMetadata folder
             if (settings.base)
             {
                 write_base_h();
+                write_base_macros_h();
                 ixx.flush_to_file(settings.output_folder + "winrt/winrt.ixx");
             }
 

cppwinrt/settings.h

@@ -31,6 +31,8 @@ namespace cppwinrt
 
         bool fastabi{};
         std::map<winmd::reader::TypeDef, winmd::reader::TypeDef> fastabi_cache;
+
+        bool component_module{}; // Generate component files using 'import winrt;' instead of #include
     };
 
     extern settings_type settings;

cppwinrt/type_writers.h

@@ -564,6 +564,19 @@ namespace cppwinrt
                 settings.brackets ? '>' : '\"');
         }
 
+        void write_root_include_guarded(std::string_view const& include)
+        {
+            auto format = R"(#ifndef WINRT_IMPL_SKIP_INCLUDES
+#include %winrt/%.h%
+#endif
+)";
+
+            write(format,
+                settings.brackets ? '<' : '\"',
+                include,
+                settings.brackets ? '>' : '\"');
+        }
+
         void write_depends(std::string_view const& ns, char impl = 0)
         {
             if (impl)
@@ -576,6 +589,18 @@ namespace cppwinrt
             }
         }
 
+        void write_depends_guarded(std::string_view const& ns, char impl = 0)
+        {
+            if (impl)
+            {
+                write_root_include_guarded(write_temp("impl/%.%", ns, impl));
+            }
+            else
+            {
+                write_root_include_guarded(ns);
+            }
+        }
+
         void save_header(char impl = 0)
         {
             auto filename{ settings.output_folder + "winrt/" };