Disallow cast/implicit conversion from LayoutUnit to int/unsigned

third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 567 matching lines @@
     LayoutUnit availableWidth = columnBlock->contentLogicalWidth();
     LayoutUnit columnGap = LayoutUnit(columnBlock->columnGap());
     LayoutUnit computedColumnWidth = max(LayoutUnit(1), LayoutUnit(columnStyle->columnWidth()));
     unsigned computedColumnCount = max<int>(1, columnStyle->columnCount());
 
     ASSERT(!columnStyle->hasAutoColumnCount() || !columnStyle->hasAutoColumnWidth());
     if (columnStyle->hasAutoColumnWidth() && !columnStyle->hasAutoColumnCount()) {
         count = computedColumnCount;
         width = ((availableWidth - ((count - 1) * columnGap)) / count).clampNegativeToZero();
     } else if (!columnStyle->hasAutoColumnWidth() && columnStyle->hasAutoColumnCount()) {
-        count = std::max(LayoutUnit(1), (availableWidth + columnGap) / (computedColumnWidth + columnGap));
+        count = std::max(LayoutUnit(1), (availableWidth + columnGap) / (computedColumnWidth + columnGap)).toUnsigned();
         width = ((availableWidth + columnGap) / count) - columnGap;
     } else {
-        count = std::max(std::min(LayoutUnit(computedColumnCount), (availableWidth + columnGap) / (computedColumnWidth + columnGap)), LayoutUnit(1));
+        count = std::max(std::min(LayoutUnit(computedColumnCount), (availableWidth + columnGap) / (computedColumnWidth + columnGap)), LayoutUnit(1)).toUnsigned();
+        count = std::max(count, 1u);

[mstensho (USE GERRIT), 2016/08/22 18:05:17]

What's this for? The line above already makes sure that it's at least
LayoutUnit(1), doesn't it?

[Xianzhu, 2016/08/22 18:15:37]

Thanks for the catch. This is garbage left from previous versions of the CL.
Removed.

         width = ((availableWidth + columnGap) / count) - columnGap;
     }
 }
 
 void LayoutMultiColumnFlowThread::createAndInsertMultiColumnSet(LayoutBox* insertBefore)
 {
     LayoutBlockFlow* multicolContainer = multiColumnBlockFlow();
     LayoutMultiColumnSet* newSet = LayoutMultiColumnSet::createAnonymous(*this, multicolContainer->styleRef());
     multicolContainer->LayoutBlock::addChild(newSet, insertBefore);
     invalidateColumnSets();
@@ skipping 449 matching lines @@
 {
     return MultiColumnLayoutState(m_lastSetWorkedOn);
 }
 
 void LayoutMultiColumnFlowThread::restoreMultiColumnLayoutState(const MultiColumnLayoutState& state)
 {
     m_lastSetWorkedOn = state.columnSet();
 }
 
 } // namespace blink