Changed QLibrary::resolve() to return a function pointer.

According to the C++ standard, there is no guarantee that
you can cast between function pointers and void pointers
without data loss (section 5.2.10-6).

Change-Id: I27f4d835e4c8ca8ecca0d76cfea9ce34491956bd
Reviewed-on: http://codereview.qt.nokia.com/1995
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

dist/changes-5.0.0

@@ -17,6 +17,9 @@ information about a particular change.
 - Unite clipping support has been removed from QPainter. The alternative is
   to unite QRegion's and using the result on QPainter.
 
+- QLibrary::resolve() now returns a function pointer instead of a void
+  pointer.
+
 ****************************************************************************
 *                           General                                        *
 ****************************************************************************

src/3rdparty/harfbuzz/src/harfbuzz-external.h

@@ -144,7 +144,7 @@ HB_CharCategory HB_GetUnicodeCharCategory(HB_UChar32 ch);
 int HB_GetUnicodeCharCombiningClass(HB_UChar32 ch);
 HB_UChar16 HB_GetMirroredChar(HB_UChar16 ch);
 
-void *HB_Library_Resolve(const char *library, int version, const char *symbol);
+void (*HB_Library_Resolve(const char *library, int version, const char *symbol))();
 
 HB_END_HEADER
 

src/3rdparty/harfbuzz/tests/linebreaking/harfbuzz-qt.cpp

@@ -79,7 +79,7 @@ void HB_GetGraphemeAndLineBreakClass(HB_UChar32 ch, HB_GraphemeClass *grapheme,
     *lineBreak = (HB_LineBreakClass) prop->line_break_class;
 }
 
-void *HB_Library_Resolve(const char *library, int version, const char *symbol)
+void (*HB_Library_Resolve(const char *library, int version, const char *symbol))()
 {
     return QLibrary::resolve(library, version, symbol);
 }

src/corelib/global/qglobal.cpp

@@ -718,6 +718,13 @@ QT_BEGIN_NAMESPACE
     \sa QtMsgHandler, qInstallMsgHandler()
 */
 
+/*! \typedef QFunctionPointer
+    \relates <QtGlobal>
+
+    This is a typedef for \c{void (*)()}, a pointer to a function that takes
+    no arguments and returns void.
+*/
+
 /*! \macro qint64 Q_INT64_C(literal)
     \relates <QtGlobal>
 

src/corelib/global/qglobal.h

@@ -1807,6 +1807,8 @@ Q_CORE_EXPORT void qt_message_output(QtMsgType, const char *buf);
 typedef void (*QtMsgHandler)(QtMsgType, const char *);
 Q_CORE_EXPORT QtMsgHandler qInstallMsgHandler(QtMsgHandler);
 
+typedef void (*QFunctionPointer)();
+
 #if !defined(Q_UNIMPLEMENTED)
 #  define Q_UNIMPLEMENTED() qWarning("%s:%d: %s: Unimplemented code.", __FILE__, __LINE__, Q_FUNC_INFO)
 #endif

src/corelib/plugin/qlibrary.cpp

@@ -447,7 +447,7 @@ QLibraryPrivate::~QLibraryPrivate()
     }
 }
 
-void *QLibraryPrivate::resolve(const char *symbol)
+QFunctionPointer QLibraryPrivate::resolve(const char *symbol)
 {
     if (!pHnd)
         return 0;
@@ -1129,7 +1129,7 @@ void QLibrary::setFileNameAndVersion(const QString &fileName, const QString &ver
     Note: In Symbian resolving with symbol names works only if the loaded
     library was built as STDDLL. Otherwise, the ordinals must be used.
 */
-void *QLibrary::resolve(const char *symbol)
+QFunctionPointer QLibrary::resolve(const char *symbol)
 {
     if (!isLoaded() && !load())
         return 0;
@@ -1152,7 +1152,7 @@ void *QLibrary::resolve(const char *symbol)
 
     \sa resolve()
 */
-void *QLibrary::resolve(const QString &fileName, const char *symbol)
+QFunctionPointer QLibrary::resolve(const QString &fileName, const char *symbol)
 {
     QLibrary library(fileName);
     return library.resolve(symbol);
@@ -1175,7 +1175,7 @@ void *QLibrary::resolve(const QString &fileName, const char *symbol)
 
     \sa resolve()
 */
-void *QLibrary::resolve(const QString &fileName, int verNum, const char *symbol)
+QFunctionPointer QLibrary::resolve(const QString &fileName, int verNum, const char *symbol)
 {
     QLibrary library(fileName, verNum);
     return library.resolve(symbol);
@@ -1199,7 +1199,7 @@ void *QLibrary::resolve(const QString &fileName, int verNum, const char *symbol)
 
     \sa resolve()
 */
-void *QLibrary::resolve(const QString &fileName, const QString &version, const char *symbol)
+QFunctionPointer QLibrary::resolve(const QString &fileName, const QString &version, const char *symbol)
 {
     QLibrary library(fileName, version);
     return library.resolve(symbol);

src/corelib/plugin/qlibrary.h

@@ -79,10 +79,10 @@ public:
     explicit QLibrary(const QString& fileName, const QString &version, QObject *parent = 0);
     ~QLibrary();
 
-    void *resolve(const char *symbol);
-    static void *resolve(const QString &fileName, const char *symbol);
-    static void *resolve(const QString &fileName, int verNum, const char *symbol);
-    static void *resolve(const QString &fileName, const QString &version, const char *symbol);
+    QFunctionPointer resolve(const char *symbol);
+    static QFunctionPointer resolve(const QString &fileName, const char *symbol);
+    static QFunctionPointer resolve(const QString &fileName, int verNum, const char *symbol);
+    static QFunctionPointer resolve(const QString &fileName, const QString &version, const char *symbol);
 
     bool load();
     bool unload();

src/corelib/plugin/qlibrary_p.h

@@ -87,7 +87,7 @@ public:
     bool loadPlugin(); // loads and resolves instance
     bool unload();
     void release();
-    void *resolve(const char *);
+    QFunctionPointer resolve(const char *);
 
     static QLibraryPrivate *findOrCreate(const QString &fileName, const QString &version = QString());
 
@@ -108,7 +108,7 @@ private:
 
     bool load_sys();
     bool unload_sys();
-    void *resolve_sys(const char *);
+    QFunctionPointer resolve_sys(const char *);
 
     QAtomicInt libraryRefCount;
     QAtomicInt libraryUnloadCount;

src/corelib/plugin/qlibrary_unix.cpp

@@ -267,29 +267,29 @@ bool QLibraryPrivate::unload_sys()
 }
 
 #ifdef Q_OS_MAC
-Q_CORE_EXPORT void *qt_mac_resolve_sys(void *handle, const char *symbol)
+Q_CORE_EXPORT QFunctionPointer qt_mac_resolve_sys(void *handle, const char *symbol)
 {
-    return dlsym(handle, symbol);
+    return QFunctionPointer(dlsym(handle, symbol));
 }
 #endif
 
-void* QLibraryPrivate::resolve_sys(const char* symbol)
+QFunctionPointer QLibraryPrivate::resolve_sys(const char* symbol)
 {
 #if defined(QT_AOUT_UNDERSCORE)
     // older a.out systems add an underscore in front of symbols
     char* undrscr_symbol = new char[strlen(symbol)+2];
     undrscr_symbol[0] = '_';
     strcpy(undrscr_symbol+1, symbol);
-    void* address = dlsym(pHnd, undrscr_symbol);
+    QFunctionPointer address = QFunctionPointer(dlsym(pHnd, undrscr_symbol));
     delete [] undrscr_symbol;
 #elif defined(QT_HPUX_LD)
-    void* address = 0;
+    QFunctionPointer address = 0;
     if (shl_findsym((shl_t*)&pHnd, symbol, TYPE_UNDEFINED, &address) < 0)
         address = 0;
 #elif defined (QT_NO_DYNAMIC_LIBRARY)
-    void *address = 0;
+    QFunctionPointer address = 0;
 #else
-    void* address = dlsym(pHnd, symbol);
+    QFunctionPointer address = QFunctionPointer(dlsym(pHnd, symbol));
 #endif
     if (!address) {
         errorString = QLibrary::tr("Cannot resolve symbol \"%1\" in %2: %3").arg(

src/corelib/plugin/qlibrary_win.cpp

@@ -113,12 +113,12 @@ bool QLibraryPrivate::unload_sys()
     return true;
 }
 
-void* QLibraryPrivate::resolve_sys(const char* symbol)
+QFunctionPointer QLibraryPrivate::resolve_sys(const char* symbol)
 {
 #ifdef Q_OS_WINCE
-    void* address = (void*)GetProcAddress(pHnd, (const wchar_t*)QString::fromLatin1(symbol).utf16());
+    FARPROC address = GetProcAddress(pHnd, (const wchar_t*)QString::fromLatin1(symbol).utf16());
 #else
-    void* address = (void*)GetProcAddress(pHnd, symbol);
+    FARPROC address = GetProcAddress(pHnd, symbol);
 #endif
     if (!address) {
         errorString = QLibrary::tr("Cannot resolve symbol \"%1\" in %2: %3").arg(
@@ -126,6 +126,6 @@ void* QLibraryPrivate::resolve_sys(const char* symbol)
     } else {
         errorString.clear();
     }
-    return address;
+    return QFunctionPointer(address);
 }
 QT_END_NAMESPACE

src/corelib/plugin/qsystemlibrary_p.h

@@ -78,20 +78,20 @@ public:
         return (m_handle != 0);
     }
 
-    void *resolve(const char *symbol)
+    QFunctionPointer resolve(const char *symbol)
     {
         if (!m_didLoad)
             load();
         if (!m_handle)
             return 0;
 #ifdef Q_OS_WINCE
-    return (void*)GetProcAddress(m_handle, (const wchar_t*)QString::fromLatin1(symbol).utf16());
+        return QFunctionPointer(GetProcAddress(m_handle, (const wchar_t*)QString::fromLatin1(symbol).utf16()));
 #else
-    return (void*)GetProcAddress(m_handle, symbol);
+        return QFunctionPointer(GetProcAddress(m_handle, symbol));
 #endif
     }
 
-    static void *resolve(const QString &libraryName, const char *symbol)
+    static QFunctionPointer resolve(const QString &libraryName, const char *symbol)
     {
         return QSystemLibrary(libraryName).resolve(symbol);
     }

src/corelib/tools/qharfbuzz.cpp

@@ -102,7 +102,7 @@ HB_UChar16 HB_GetMirroredChar(HB_UChar16 ch)
     return QChar::mirroredChar(ch);
 }
 
-void *HB_Library_Resolve(const char *library, int version, const char *symbol)
+void (*HB_Library_Resolve(const char *library, int version, const char *symbol))()
 {
 #ifdef QT_NO_LIBRARY
     return 0;

src/dbus/qdbus_symbols.cpp

@@ -48,7 +48,7 @@
 
 QT_BEGIN_NAMESPACE
 
-void *qdbus_resolve_me(const char *name);
+void (*qdbus_resolve_me(const char *name))();
 
 #if !defined QT_LINKED_LIBDBUS
 
@@ -95,20 +95,19 @@ bool qdbus_loadLibDBus()
     return false;
 }
 
-void *qdbus_resolve_conditionally(const char *name)
+void (*qdbus_resolve_conditionally(const char *name))()
 {
     if (qdbus_loadLibDBus())
         return qdbus_libdbus->resolve(name);
     return 0;
 }
 
-void *qdbus_resolve_me(const char *name)
+void (*qdbus_resolve_me(const char *name))()
 {
-    void *ptr = 0;
     if (!qdbus_loadLibDBus())
         qFatal("Cannot find libdbus-1 in your system to resolve symbol '%s'.", name);
 
-    ptr = qdbus_libdbus->resolve(name);
+    QFunctionPointer ptr = qdbus_libdbus->resolve(name);
     if (!ptr)
         qFatal("Cannot resolve '%s' in your libdbus-1.", name);
 

src/dbus/qdbus_symbols_p.h

@@ -63,8 +63,8 @@ QT_BEGIN_NAMESPACE
 
 #if !defined QT_LINKED_LIBDBUS
 
-void *qdbus_resolve_conditionally(const char *name); // doesn't print a warning
-void *qdbus_resolve_me(const char *name); // prints a warning
+void (*qdbus_resolve_conditionally(const char *name))(); // doesn't print a warning
+void (*qdbus_resolve_me(const char *name))(); // prints a warning
 bool qdbus_loadLibDBus();
 
 # define DEFINEFUNC(ret, func, args, argcall, funcret)          \

src/gui/kernel/qapplication_x11.cpp

@@ -467,8 +467,8 @@ extern bool qt_is_gui_used;
     \c XFIXES_MAJOR - it is a part of soname and may differ from the Xfixes
     version.
 */
-static void* qt_load_library_runtime(const char *library, int vernum,
-                                     int highestVernum, const char *symbol)
+static QFunctionPointer qt_load_library_runtime(const char *library, int vernum,
+                                                int highestVernum, const char *symbol)
 {
     QList<int> versions;
     // we try to load in the following order:
@@ -483,7 +483,7 @@ static void* qt_load_library_runtime(const char *library, int vernum,
     Q_FOREACH(int version, versions) {
         QLatin1String libName(library);
         QLibrary xfixesLib(libName, version);
-        void *ptr = xfixesLib.resolve(symbol);
+        QFunctionPointer ptr = xfixesLib.resolve(symbol);
         if (ptr)
             return ptr;
     }

src/gui/text/qrawfont_win.cpp

@@ -529,7 +529,8 @@ void QRawFontPrivate::platformCleanUp()
 {
     if (fontHandle != NULL) {
         if (ptrRemoveFontMemResourceEx == NULL) {
-            void *func = QSystemLibrary::resolve(QLatin1String("gdi32"), "RemoveFontMemResourceEx");
+            QFunctionPointer func =
+                    QSystemLibrary::resolve(QLatin1String("gdi32"), "RemoveFontMemResourceEx");
             ptrRemoveFontMemResourceEx =
                     reinterpret_cast<QRawFontPrivate::PtrRemoveFontMemResourceEx>(func);
         }
@@ -572,7 +573,8 @@ void QRawFontPrivate::platformLoadFromData(const QByteArray &_fontData,
         }
 
         if (ptrAddFontMemResourceEx == NULL || ptrRemoveFontMemResourceEx == NULL) {
-            void *func = QSystemLibrary::resolve(QLatin1String("gdi32"), "RemoveFontMemResourceEx");
+            QFunctionPointer func =
+                    QSystemLibrary::resolve(QLatin1String("gdi32"), "RemoveFontMemResourceEx");
             ptrRemoveFontMemResourceEx =
                     reinterpret_cast<QRawFontPrivate::PtrRemoveFontMemResourceEx>(func);
 

src/opengl/qgl_x11.cpp

@@ -347,13 +347,13 @@ static void find_trans_colors()
   QGLFormat UNIX/GLX-specific code
  *****************************************************************************/
 
-void* qglx_getProcAddress(const char* procName)
+void (*qglx_getProcAddress(const char* procName))()
 {
     // On systems where the GL driver is pluggable (like Mesa), we have to use
     // the glXGetProcAddressARB extension to resolve other function pointers as
     // the symbols wont be in the GL library, but rather in a plugin loaded by
     // the GL library.
-    typedef void* (*qt_glXGetProcAddressARB)(const char *);
+    typedef void (*(*qt_glXGetProcAddressARB)(const char *))();
     static qt_glXGetProcAddressARB glXGetProcAddressARB = 0;
     static bool triedResolvingGlxGetProcAddress = false;
     if (!triedResolvingGlxGetProcAddress) {
@@ -378,7 +378,7 @@ void* qglx_getProcAddress(const char* procName)
         }
     }
 
-    void *procAddress = 0;
+    void (*procAddress)() = 0;
     if (glXGetProcAddressARB)
         procAddress = glXGetProcAddressARB(procName);
 
@@ -387,7 +387,7 @@ void* qglx_getProcAddress(const char* procName)
     if (!procAddress) {
         void *handle = dlopen(NULL, RTLD_LAZY);
         if (handle) {
-            procAddress = dlsym(handle, procName);
+            procAddress = (void (*)())dlsym(handle, procName);
             dlclose(handle);
         }
     }

src/opengl/qglpixelbuffer_x11.cpp

@@ -93,7 +93,7 @@ static _glXMakeContextCurrent qt_glXMakeContextCurrent = 0;
 #define glXGetFBConfigAttrib qt_glXGetFBConfigAttrib
 #define glXMakeContextCurrent qt_glXMakeContextCurrent
 
-extern void* qglx_getProcAddress(const char* procName); // in qgl_x11.cpp
+extern void (*qglx_getProcAddress(const char* procName))(); // in qgl_x11.cpp
 
 static bool qt_resolve_pbuffer_extensions()
 {

src/plugins/platforms/xlib/qxlibstatic.cpp

@@ -218,8 +218,8 @@ static const char * x11_atomnames = {
     \c XFIXES_MAJOR - it is a part of soname and may differ from the Xfixes
     version.
 */
-static void* qt_load_library_runtime(const char *library, int vernum,
-                                     int highestVernum, const char *symbol)
+static QFunctionPointer qt_load_library_runtime(const char *library, int vernum,
+                                                int highestVernum, const char *symbol)
 {
     QList<int> versions;
     // we try to load in the following order:
@@ -234,7 +234,7 @@ static void* qt_load_library_runtime(const char *library, int vernum,
     Q_FOREACH(int version, versions) {
         QLatin1String libName(library);
         QLibrary xfixesLib(libName, version);
-        void *ptr = xfixesLib.resolve(symbol);
+        QFunctionPointer ptr = xfixesLib.resolve(symbol);
         if (ptr)
             return ptr;
     }

tests/auto/qlibrary/tst_qlibrary.cpp

@@ -297,7 +297,7 @@ void tst_QLibrary::unload_after_implicit_load()
 #endif
 
     QLibrary library( "./mylib" );
-    void *p = library.resolve("mylibversion");
+    QFunctionPointer p = library.resolve("mylibversion");
     QVERIFY(p); // Check if it was loaded
     QVERIFY(library.isLoaded());
     QVERIFY(library.unload());