QWindowsFontDatabase/QWindowsXPStyle: Fix compilation with g++ 8.1/MinGW

Silence warnings about copying/clearing memory types which g++
considers non-trivial, for example:

windows\qwindowsfontdatabase.cpp:1003:75: error: 'void* memcpy(void*, const void*, size_t)' copying an object of non-trivial type 'class QChar' from an array of 'const ushort' {aka 'const short unsigned int'} [-Werror=class-memaccess]
         memcpy(faceNamePtr, faceName.utf16(), sizeof(wchar_t) * nameLength);
qwindowsxpstyle.cpp:946:46: error: 'void* memset(void*, int, size_t)' clearing an object of non-trivial type 'struct ThemeMapData'; use assignment or value-initialization instead [-Werror=class-memaccess]
                 memset(&data, 0, sizeof(data));
                                              ^
qwindowsxpstyle.cpp:1053:38: error: 'void* memset(void*, int, size_t)' clearing an object of non-trivial type 'struct ThemeMapData'; use assignment or value-initialization instead [-Werror=class-memaccess]
         memset(&data, 0, sizeof(data));

by introducing a cast.

Task-number: QTBUG-68742
Task-number: QTQAINFRA-2095
Change-Id: I160eb5fc7b64a2bc404e1fa61d306af2662d1252
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp b/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
index 9d2e770191..36a8afb453 100644
--- a/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
+++ b/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
@@ -943,7 +943,7 @@ bool QWindowsXPStylePrivate::drawBackgroundThruNativeBuffer(XPThemeData &themeDa
         if (!isCached) {
             // SHORTCUT: If the part's state has no data, cache it for NOOP later
             if (!stateHasData) {
-                memset(&data, 0, sizeof(data));
+                memset(static_cast<void *>(&data), 0, sizeof(data));
                 data.dataValid = true;
                 alphaCache.insert(key, data);
                 return true;
@@ -1050,7 +1050,7 @@ bool QWindowsXPStylePrivate::drawBackgroundThruNativeBuffer(XPThemeData &themeDa
 
     // Add to theme part cache
     if (!isCached) {
-        memset(&data, 0, sizeof(data));
+        memset(static_cast<void *>(&data), 0, sizeof(data));
         data.dataValid = true;
         data.partIsTransparent = partIsTransparent;
         data.alphaType = alphaType;