Flexbox flex: 1 incorrectly sets flex-basis to 0px

Source/core/rendering/RenderFlexibleBox.cpp

 /*
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@@ skipping 584 matching lines @@
         child->setLocation(location.transposedPoint());
 }
 
 LayoutUnit RenderFlexibleBox::mainAxisBorderAndPaddingExtentForChild(RenderBox* child) const
 {
     return isHorizontalFlow() ? child->borderAndPaddingWidth() : child->borderAndPaddingHeight();
 }
 
 static inline bool preferredMainAxisExtentDependsOnLayout(const Length& flexBasis, bool hasInfiniteLineLength)
 {
-    return flexBasis.isAuto() || (flexBasis.isFixed() && !flexBasis.value() && hasInfiniteLineLength);

[cbiesinger, 2014/08/21 23:54:23]

So, the reason this code exists is a bit complicated.
https://chromium.googlesource.com/chromium/blink/+/4e1f04846b7b0c605dbe7688c2...
has the description -- 0px plus hasInfiniteLength means we need to layout,
because we made that basically behave like 0%.
So with this bug fixed, we should remove all the hasInfiniteLineLength code
(that can happen in a separate patch), but either way, you should remove
hasInfinteLineLength here.

Now, the other thing here - all percentages depend on layout (not just 0),
unless we have a definite specified size, right? So this should be
flexBasis.isAuto() || flexBasis.isPercent() at a minimum. There's probably a way
to optimize that further.

[harpreet.sk, 2014/08/22 15:13:35]

Thanks Chris for the review. We cannot simply remove hasFiniteLineLength here. I
tried to remove it but because of it many layout tests are getting failed. We
need to do a lot of refactoring as well as need to add many things like will
have take flex-basis into account while computing computeIntrinsicLogicalWidths
(A FIXME was added in the patch which you have mentioned above by ojan). I will
look into this when i'll upload a sepearate patch for removing all the
hasInfiniteLineLength code. As for this patch we can keep hasInfiniteLineLength
for time being.
Yes you are correct all percentages depends on layout and not just 0. Removed
the !flexBasis.value() check.

+    return flexBasis.isAuto() || (flexBasis.isPercent() && !flexBasis.value() && hasInfiniteLineLength);
 }
 
 bool RenderFlexibleBox::childPreferredMainAxisContentExtentRequiresLayout(RenderBox* child, bool hasInfiniteLineLength) const
 {
     return preferredMainAxisExtentDependsOnLayout(flexBasisForChild(child), hasInfiniteLineLength) && hasOrthogonalFlow(child);
 }
 
 LayoutUnit RenderFlexibleBox::preferredMainAxisContentExtentForChild(RenderBox* child, bool hasInfiniteLineLength, bool relayoutChildren)
 {
     child->clearOverrideSize();
@@ skipping 786 matching lines @@
             ASSERT(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(child, newOffset - originalOffset);
         }
     }
 }
 
 }