Add test for including Windows headers before wx headers

Test both ANSI and WIDE (with/without UNICODE) builds.

build/cmake/tests/CMakeLists.txt

@@ -11,3 +11,6 @@ add_subdirectory(base)
 add_subdirectory(drawing)
 add_subdirectory(gui)
 add_subdirectory(headers)
+if(WIN32)
+    add_subdirectory(win32)
+endif()

build/cmake/tests/win32/CMakeLists.txt

@@ -0,0 +1,22 @@
+#############################################################################
+# Name:        build/cmake/tests/win32/CMakeLists.txt
+# Purpose:     CMake file for win32 test
+# Author:      Maarten Bent
+# Created:     2025-11-15
+# Copyright:   (c) 2025 wxWidgets development team
+# Licence:     wxWindows licence
+#############################################################################
+
+set(TEST_SRC
+    testwin32.cpp
+)
+
+wx_add_test(test_win32_wide ${TEST_SRC})
+if(TARGET test_win32_wide)
+    target_compile_definitions(test_win32_wide PRIVATE UNICODE _UNICODE)
+endif()
+
+wx_add_test(test_win32_ansi ${TEST_SRC})
+if(TARGET test_win32_ansi)
+    target_compile_definitions(test_win32_ansi PRIVATE _SBCS)
+endif()

tests/testwin32.cpp

@@ -0,0 +1,118 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        tests/testwin32.cpp
+// Purpose:     Test including Windows headers before wxWidgets headers
+// Author:      Maarten Bent
+// Created:     2025-11-15
+// Copyright:   (c) 2025 wxWidgets development team
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WIN32
+    #error This is a Windows/win32 specific test
+#endif
+
+// When including Windows headers before wx headers, the functions declared
+// in wx/msw/winundef.h need to match the ANSI/WIDE variant in the Windows
+// headers. By default the WIDE variant is declared, but if ANSI Windows is
+// used, define wxNO_WIN32_W.
+#define _WINSOCK_DEPRECATED_NO_WARNINGS
+#define _CRT_SECURE_NO_WARNINGS
+#include <winsock2.h>
+#include <Windows.h>
+#ifndef UNICODE
+    #define wxNO_WIN32_W
+#endif
+
+#include "wx/wxprec.h"
+
+// include all headers, so incorrect usage of ANSI/WIDE win32 API in public
+// headers is detected
+#include "allheaders.h"
+
+#ifdef wxHAS_NATIVE_WINDOW
+
+class NativeWindow : public wxNativeWindow
+{
+public:
+    explicit NativeWindow(wxWindow* parent)
+        : wxNativeWindow()
+    {
+        const wxSize size = FromDIP(wxSize(140, 30));
+
+        HWND hwnd = ::CreateWindow
+                      (
+                        TEXT("BUTTON"),
+                        TEXT("Press me to do it"),
+                        WS_CHILD | WS_VISIBLE | BS_SPLITBUTTON,
+                        0, 0, size.x, size.y,
+                        (HWND)parent->GetHWND(), 0, nullptr, nullptr
+                      );
+        if ( !hwnd )
+        {
+            wxLogError("Creating split button failed.");
+            return;
+        }
+
+        (void)Create(parent, wxID_ANY, hwnd);
+    }
+
+    virtual ~NativeWindow()
+    {
+        Disown();
+    }
+
+protected:
+    virtual bool
+    MSWOnNotify(int idCtrl, WXLPARAM lParam, WXLPARAM *result) override
+    {
+        const NMHDR* hdr = reinterpret_cast<NMHDR*>(lParam);
+        if ( hdr->code != BCN_DROPDOWN )
+            return wxNativeWindow::MSWOnNotify(idCtrl, lParam, result);
+
+        const NMBCDROPDOWN* dd = reinterpret_cast<NMBCDROPDOWN*>(lParam);
+
+        wxMenu menu;
+        menu.Append(wxID_NEW);
+        menu.AppendSeparator();
+        menu.Append(wxID_ABOUT);
+        PopupMenu(&menu, wxPoint(dd->rcButton.right, dd->rcButton.bottom));
+
+        return true;
+    }
+};
+
+#endif // wxHAS_NATIVE_WINDOW
+
+class MyFrame : public wxFrame
+{
+public:
+    MyFrame(const wxString& title)
+        : wxFrame(nullptr, wxID_ANY, title)
+    {
+        wxSizer* m_sizerCtrl = new wxBoxSizer(wxHORIZONTAL);
+#ifdef wxHAS_NATIVE_WINDOW
+        wxNativeWindow* m_nativeWindow = new NativeWindow(this);
+        m_sizerCtrl->Add(m_nativeWindow, wxSizerFlags(1).Expand().Border());
+#endif
+        SetSizer(m_sizerCtrl);
+
+        CallAfter([&]() { Close(true); });
+    }
+
+};
+
+class MyApp : public wxApp
+{
+public:
+    virtual bool OnInit() override
+    {
+        if (!wxApp::OnInit())
+            return false;
+
+        MyFrame* frame = new MyFrame("win32 test");
+        frame->Show(true);
+        return true;
+    }
+};
+
+wxIMPLEMENT_APP(MyApp);