QPixelLayout: remove explicit array sizes

For qPixelLayouts, there's a static_assert right below it that checks
that the array has a specific size, as a guard for extending
QImage::NImageFormats without also extending the array. Giving an
explicit size to qPixelLayouts defeats the entire purpose.

For the other arrays of function pointers, drop the sizing and add the
missing static_asserts.

Use std::size as a drive-by.

This work has been kindly sponsored by the QGIS project
(https://qgis.org/).

Change-Id: Ic791a706a8ae964e3aee482f23b7eeeedf97bdc6
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

src/gui/painting/qpixellayout.cpp

@@ -1661,7 +1661,7 @@ static const QRgba64 *QT_FASTCALL fetchRGBA32FPMToRGBA64PM(QRgba64 *buffer, cons
 // convertToArgb32() assumes that no color channel is less than 4 bits.
 // storeRGBFromARGB32PM() assumes that no color channel is more than 8 bits.
 // QImage::rgbSwapped() assumes that the red and blue color channels have the same number of bits.
-QPixelLayout qPixelLayouts[QImage::NImageFormats] = {
+QPixelLayout qPixelLayouts[] = {
     { false, false, QPixelLayout::BPPNone, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr }, // Format_Invalid
     { false, false, QPixelLayout::BPP1MSB, nullptr,
       convertIndexedToARGB32PM, convertIndexedTo<QRgba64>,
@@ -1781,7 +1781,7 @@ QPixelLayout qPixelLayouts[QImage::NImageFormats] = {
       storeRGB32FFromRGB32, storeRGB32FFromRGB32 }, // Format_RGBA32FPx4_Premultiplied
 };
 
-static_assert(sizeof(qPixelLayouts) / sizeof(*qPixelLayouts) == QImage::NImageFormats);
+static_assert(std::size(qPixelLayouts) == QImage::NImageFormats);
 
 static void QT_FASTCALL convertFromRgb64(uint *dest, const QRgba64 *src, int length)
 {
@@ -1916,7 +1916,7 @@ static void QT_FASTCALL storeRGBA32FPMFromRGBA64PM(uchar *dest, const QRgba64 *s
         d[i] = qConvertRgb64ToRgbaF32(src[i]);
 }
 
-ConvertAndStorePixelsFunc64 qStoreFromRGBA64PM[QImage::NImageFormats] = {
+ConvertAndStorePixelsFunc64 qStoreFromRGBA64PM[] = {
     nullptr,
     nullptr,
     nullptr,
@@ -1955,6 +1955,8 @@ ConvertAndStorePixelsFunc64 qStoreFromRGBA64PM[QImage::NImageFormats] = {
     storeRGBA32FPMFromRGBA64PM,
 };
 
+static_assert(std::size(qStoreFromRGBA64PM) == QImage::NImageFormats);
+
 #if QT_CONFIG(raster_fp)
 static void QT_FASTCALL convertToRgbaF32(QRgbaFloat32 *dest, const uint *src, int length)
 {
@@ -2000,7 +2002,7 @@ static const QRgbaFloat32 * QT_FASTCALL convertRGB30ToRGBA32F(QRgbaFloat32 *buff
     return buffer;
 }
 
-ConvertToFPFunc qConvertToRGBA32F[QImage::NImageFormats] = {
+ConvertToFPFunc qConvertToRGBA32F[] = {
     nullptr,
     convertIndexedTo<QRgbaFloat32>,
     convertIndexedTo<QRgbaFloat32>,
@@ -2039,6 +2041,8 @@ ConvertToFPFunc qConvertToRGBA32F[QImage::NImageFormats] = {
     nullptr,
 };
 
+static_assert(std::size(qConvertToRGBA32F) == QImage::NImageFormats);
+
 static const QRgbaFloat32 *QT_FASTCALL fetchRGBX64ToRGBA32F(QRgbaFloat32 *buffer, const uchar *src, int index, int count,
                                                         const QList<QRgb> *, QDitherInfo *)
 {
@@ -2103,7 +2107,7 @@ static const QRgbaFloat32 *QT_FASTCALL fetchRGBA32F(QRgbaFloat32 *, const uchar
     return s;
 }
 
-FetchAndConvertPixelsFuncFP qFetchToRGBA32F[QImage::NImageFormats] = {
+FetchAndConvertPixelsFuncFP qFetchToRGBA32F[] = {
     nullptr,
     fetchIndexedToRGBA32F<QPixelLayout::BPP1MSB>,
     fetchIndexedToRGBA32F<QPixelLayout::BPP1LSB>,
@@ -2142,6 +2146,8 @@ FetchAndConvertPixelsFuncFP qFetchToRGBA32F[QImage::NImageFormats] = {
     fetchRGBA32F,
 };
 
+static_assert(std::size(qFetchToRGBA32F) == QImage::NImageFormats);
+
 static void QT_FASTCALL convertFromRgba32f(uint *dest, const QRgbaFloat32 *src, int length)
 {
     for (int i = 0; i < length; ++i)
@@ -2278,7 +2284,7 @@ static void QT_FASTCALL storeRGBA32FPMFromRGBA32F(uchar *dest, const QRgbaFloat3
     }
 }
 
-ConvertAndStorePixelsFuncFP qStoreFromRGBA32F[QImage::NImageFormats] = {
+ConvertAndStorePixelsFuncFP qStoreFromRGBA32F[] = {
     nullptr,
     nullptr,
     nullptr,
@@ -2316,6 +2322,9 @@ ConvertAndStorePixelsFuncFP qStoreFromRGBA32F[QImage::NImageFormats] = {
     storeRGBA32FFromRGBA32F,
     storeRGBA32FPMFromRGBA32F,
 };
+
+static_assert(std::size(qStoreFromRGBA32F) == QImage::NImageFormats);
+
 #endif // QT_CONFIG(raster_fp)
 
 QT_END_NAMESPACE

src/gui/painting/qpixellayout_p.h

@@ -321,12 +321,12 @@ struct QPixelLayout
 extern ConvertAndStorePixelsFunc64 qStoreFromRGBA64PM[QImage::NImageFormats];
 
 #if QT_CONFIG(raster_fp)
-extern ConvertToFPFunc qConvertToRGBA32F[QImage::NImageFormats];
-extern FetchAndConvertPixelsFuncFP qFetchToRGBA32F[QImage::NImageFormats];
-extern ConvertAndStorePixelsFuncFP qStoreFromRGBA32F[QImage::NImageFormats];
+extern ConvertToFPFunc qConvertToRGBA32F[];
+extern FetchAndConvertPixelsFuncFP qFetchToRGBA32F[];
+extern ConvertAndStorePixelsFuncFP qStoreFromRGBA32F[];
 #endif
 
-extern QPixelLayout qPixelLayouts[QImage::NImageFormats];
+extern QPixelLayout qPixelLayouts[];
 
 extern MemRotateFunc qMemRotateFunctions[QPixelLayout::BPPCount][3];