Adjust QSGTexture comparisonKey type

The original choice was int, simply following textureId(). This was later
deemed insufficient: instead of a GLuint, the value is now often a 64-bit
value (on 64 bit systems), based on a pointer, since the identity of a texture
in the RHI world is the QRhiTexture* itself. In a custom texture implementation
it is likely that the value here is the value of a native object handle, either
a pointer or some 32 or 64 bit integer.

Inspired by the recent QSGTexture::NativeTexture struct change (void* -> quint64),
switch to a qint64 which is big enough to hold all these without truncation.

We choose a signed value here, in order to allow for the following pattern that
is widespread in material compare() implementations:
if (qint64 diff = m_texture->comparisonKey() - other->texture()->comparisonKey())
  return diff;

Fixes: QTBUG-83769
Change-Id: I8bdae8cd835282358ded53b3703142b8f26e4400
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/quick/scenegraph/qsgrhishadereffectnode.cpp b/src/quick/scenegraph/qsgrhishadereffectnode.cpp
index 0508ae9c7a..2afb40a61e 100644
--- a/src/quick/scenegraph/qsgrhishadereffectnode.cpp
+++ b/src/quick/scenegraph/qsgrhishadereffectnode.cpp
@@ -494,7 +494,7 @@ int QSGRhiShaderEffectMaterial::compare(const QSGMaterial *other) const
             QSGTexture *t1 = tp1->texture();
             QSGTexture *t2 = tp2->texture();
             if (t1 && t2) {
-                if (int diff = t1->comparisonKey() - t2->comparisonKey())
+                if (qint64 diff = t1->comparisonKey() - t2->comparisonKey())
                     return diff;
             } else {
                 if (!t1 && t2)