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QRegion: upgrade Q_ASSUME to Q_ASSERT

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This is to fix the warning

qregion.cpp:3582:12: error: ‘ET.EdgeTable::ymax’ may be used uninitialized [-Werror=maybe-uninitialized]

Because the previous code in PolygonRegion() was:
    Q_ASSUME(Count > 1);

But Q_ASSUME is becoming a no-op with GCC 12, so when this disappears,
compiler rightly considered Count < 2 as a valid input. Therefore, when
CreateETandAET() was called and had

   if (count < 2)
       return;

The compiler again rightly concluded that it was a valid condition
(after all, you're checking it!), leading to ET.ymax being used
uninitialized.

Since that Q_ASSUME really meant the condition of Count < 2 was not
permitted, we may as well upgrade to Q_ASSERT in both places.

Change-Id: I7f354474adce419ca6c2fffd1748119ef0092fa4
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
This commit is contained in:
Thiago Macieira 2023-02-28 10:50:35 -08:00
parent 52c7f699ac
commit 8dbceaa398
1 changed files with 2 additions and 3 deletions
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5
src/gui/painting/qregion.cpp
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@ -3191,8 +3191,7 @@ static void CreateETandAET(int count, const QPoint *pts,
int iSLLBlock = 0;
int dy;
if (count < 2)
return;
Q_ASSERT(count > 1);
/*
* initialize the Active Edge Table
@ -3538,7 +3537,7 @@ static QRegionPrivate *PolygonRegion(const QPoint *Pts, int Count, int rule)
POINTBLOCK *tmpPtBlock;
int numFullPtBlocks = 0;
Q_ASSUME(Count > 1);
Q_ASSERT(Count > 1);
region = new QRegionPrivate;