Bug 1744363 Part 2 - Make nsFlexContainerFrame::ReflowChildren() return nsReflowStatus of children. r=dholbert

This is a preparation for Part 4. We need to tell apart the children reflow
status between incomplete and overflow-incomplete.

Differential Revision: https://phabricator.services.mozilla.com/D188530

layout/generic/nsFlexContainerFrame.cpp

@@ -4653,7 +4653,7 @@ void nsFlexContainerFrame::Reflow(nsPresContext* aPresContext,
 
   const LogicalSize availableSizeForItems =
       ComputeAvailableSizeForItems(aReflowInput, borderPadding);
-  const auto [maxBlockEndEdgeOfChildren, anyChildIncomplete] =
+  const auto [maxBlockEndEdgeOfChildren, childrenStatus] =
       ReflowChildren(aReflowInput, containerSize, availableSizeForItems,
                      borderPadding, axisTracker, flr, fragmentData);
 
@@ -4689,8 +4689,8 @@ void nsFlexContainerFrame::Reflow(nsPresContext* aPresContext,
 
   PopulateReflowOutput(aReflowOutput, aReflowInput, aStatus, contentBoxSize,
                        borderPadding, consumedBSize, mayNeedNextInFlow,
-                       maxBlockEndEdgeOfChildren, anyChildIncomplete,
-                       axisTracker, flr);
+                       maxBlockEndEdgeOfChildren, childrenStatus, axisTracker,
+                       flr);
 
   if (wm.IsVerticalRL()) {
     // If the final border-box block-size is different from the tentative one,
@@ -5391,13 +5391,13 @@ struct FirstLineOrFirstItemBAxisMetrics final {
   Maybe<std::pair<nscoord, nscoord>> mMaxBEndEdge;
 };
 
-std::tuple<nscoord, bool> nsFlexContainerFrame::ReflowChildren(
+std::tuple<nscoord, nsReflowStatus> nsFlexContainerFrame::ReflowChildren(
     const ReflowInput& aReflowInput, const nsSize& aContainerSize,
     const LogicalSize& aAvailableSizeForItems,
     const LogicalMargin& aBorderPadding, const FlexboxAxisTracker& aAxisTracker,
     FlexLayoutResult& aFlr, PerFragmentFlexData& aFragmentData) {
   if (HidesContentForLayout()) {
-    return {0, false};
+    return {0, nsReflowStatus()};
   }
 
   // Before giving each child a final reflow, calculate the origin of the
@@ -5660,11 +5660,16 @@ std::tuple<nscoord, bool> nsFlexContainerFrame::ReflowChildren(
                        containerContentBoxOrigin, aContainerSize);
   }
 
-  const bool anyChildIncomplete = PushIncompleteChildren(
-      pushedItems, incompleteItems, overflowIncompleteItems);
+  nsReflowStatus childrenStatus;
+  if (!pushedItems.IsEmpty() || !incompleteItems.IsEmpty()) {
+    childrenStatus.SetIncomplete();
+  } else if (!overflowIncompleteItems.IsEmpty()) {
+    childrenStatus.SetOverflowIncomplete();
+  }
+  PushIncompleteChildren(pushedItems, incompleteItems, overflowIncompleteItems);
 
   // TODO: Try making this a fatal assertion after we fix bug 1751260.
-  NS_ASSERTION(!anyChildIncomplete ||
+  NS_ASSERTION(childrenStatus.IsFullyComplete() ||
                    aAvailableSizeForItems.BSize(flexWM) != NS_UNCONSTRAINEDSIZE,
                "We shouldn't have any incomplete children if the available "
                "block-size is unconstrained!");
@@ -5677,7 +5682,7 @@ std::tuple<nscoord, bool> nsFlexContainerFrame::ReflowChildren(
     aFragmentData.mCumulativeBEndEdgeShift += bAxisMetrics.mBEndEdgeShift;
   }
 
-  return {maxBlockEndEdgeOfChildren, anyChildIncomplete};
+  return {maxBlockEndEdgeOfChildren, childrenStatus};
 }
 
 void nsFlexContainerFrame::PopulateReflowOutput(
@@ -5685,8 +5690,8 @@ void nsFlexContainerFrame::PopulateReflowOutput(
     nsReflowStatus& aStatus, const LogicalSize& aContentBoxSize,
     const LogicalMargin& aBorderPadding, const nscoord aConsumedBSize,
     const bool aMayNeedNextInFlow, const nscoord aMaxBlockEndEdgeOfChildren,
-    const bool aAnyChildIncomplete, const FlexboxAxisTracker& aAxisTracker,
-    FlexLayoutResult& aFlr) {
+    const nsReflowStatus& aChildrenStatus,
+    const FlexboxAxisTracker& aAxisTracker, FlexLayoutResult& aFlr) {
   const WritingMode flexWM = aReflowInput.GetWritingMode();
 
   // Compute flex container's desired size (in its own writing-mode).
@@ -5720,7 +5725,7 @@ void nsFlexContainerFrame::PopulateReflowOutput(
           effectiveContentBSizeWithBStartBP, aMaxBlockEndEdgeOfChildren);
 
       if ((aReflowInput.ComputedBSize() != NS_UNCONSTRAINEDSIZE ||
-           !aAnyChildIncomplete) &&
+           aChildrenStatus.IsFullyComplete()) &&
           aMaxBlockEndEdgeOfChildren >= effectiveContentBSizeWithBStartBP) {
         // We have some tall unbreakable child that's sticking off the end of
         // our fragment, *and* forcing us to consume all of our remaining
@@ -5789,7 +5794,7 @@ void nsFlexContainerFrame::PopulateReflowOutput(
   // to add it in.
   desiredSizeInFlexWM.BSize(flexWM) += blockEndContainerBP;
 
-  if (aStatus.IsComplete() && aAnyChildIncomplete) {
+  if (aStatus.IsComplete() && !aChildrenStatus.IsFullyComplete()) {
     aStatus.SetOverflowIncomplete();
     aStatus.SetNextInFlowNeedsReflow();
   }

layout/generic/nsFlexContainerFrame.h

@@ -531,9 +531,8 @@ class nsFlexContainerFrame final : public nsContainerFrame,
    *                                   children of this fragment in this frame's
    *                                   coordinate space (as returned by
    *                                   ReflowChildren()).
-   * @param aAnyChildIncomplete true if any child being reflowed is incomplete;
-   *                            false otherwise (as returned by
-   *                            ReflowChildren()).
+   * @param aChildrenStatus the reflow status of children (as returned by
+   *                        ReflowChildren()).
    * @param aFlr the result returned by DoFlexLayout.
    *             Note: aFlr is mostly an "input" parameter, but we use
    *             aFlr.mAscent as an "in/out" parameter; it's initially the
@@ -548,7 +547,8 @@ class nsFlexContainerFrame final : public nsContainerFrame,
       nsReflowStatus& aStatus, const mozilla::LogicalSize& aContentBoxSize,
       const mozilla::LogicalMargin& aBorderPadding,
       const nscoord aConsumedBSize, const bool aMayNeedNextInFlow,
-      const nscoord aMaxBlockEndEdgeOfChildren, const bool aAnyChildIncomplete,
+      const nscoord aMaxBlockEndEdgeOfChildren,
+      const nsReflowStatus& aChildrenStatus,
       const FlexboxAxisTracker& aAxisTracker, FlexLayoutResult& aFlr);
 
   /**
@@ -571,10 +571,13 @@ class nsFlexContainerFrame final : public nsContainerFrame,
    *                      updated and become our PerFragmentFlexData.
    * @return nscoord the maximum block-end edge of children of this fragment in
    *                 flex container's coordinate space.
-   * @return bool true if any child being reflowed is incomplete; false
-   *              otherwise.
+   * @return nsReflowStatus the reflow status of children (i.e. flex items). If
+   *                        any child had an incomplete reflow status, then this
+   *                        will be Incomplete. Otherwise, if any child had an
+   *                        overflow-incomplete reflow status, this will be
+   *                        OverflowIncomplete.
    */
-  std::tuple<nscoord, bool> ReflowChildren(
+  std::tuple<nscoord, nsReflowStatus> ReflowChildren(
       const ReflowInput& aReflowInput, const nsSize& aContainerSize,
       const mozilla::LogicalSize& aAvailableSizeForItems,
       const mozilla::LogicalMargin& aBorderPadding,