tdf#125685 sw: disregard footnotes in follow table on table split

The first problem here is that the table isn't fully formatted; it fails
with:

warn:legacy.osl:22975:22975:sw/source/core/layout/tabfrm.cxx:2639: debug assertion: <SwTabFrame::MakeAll()> - format of table lowers suppressed by fix i44910

The situation is that there is a big table split across pages; the first
line of the table would fit onto the previous page so its follow frame
moves backward and then the table frame tries to split again.

During SwTabFrame::Split(), all the frames in the table are formatted,
and at that point a footnote that was on the next page is moved to this
page.

A nested table frame also splits, such that it fits inside the page...
but then the split of the outer table fails by 5 twips, because the
moved footnote has reduced the space available for the outer table.

The footnote is anchored in the inner table's follow frame, which would
be moved to the next page anyway, taking the footnote with it.

Fix this in lcl_RecalcSplitLine() by checking for footnotes that are
anchored in the follow frame of the top-level table being split, and
adding their height to the available space on the page.

Fixing the first problem avoids the crash as well; the crash happens
since 18765b9f and it's rather hard to
avoid it in a situation where formatting starts at the end and recurses
into an unformatted table preceding it, which isn't supposed to happen.

Change-Id: I85286583c1c4930468a1c283afc98504cd35bb71
Reviewed-on: https://gerrit.libreoffice.org/73465
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>

sw/source/core/layout/tabfrm.cxx

@@ -47,6 +47,7 @@
 #include <cellfrm.hxx>
 #include <flyfrms.hxx>
 #include <txtfrm.hxx>
+#include <ftnfrm.hxx>
 #include <notxtfrm.hxx>
 #include <htmltbl.hxx>
 #include <sectfrm.hxx>
@@ -715,7 +716,39 @@ static bool lcl_RecalcSplitLine( SwRowFrame& rLastLine, SwRowFrame& rFollowLine,
     // #i26945# - include check, if objects fit
     const SwTwips nDistanceToUpperPrtBottom =
         aRectFnSet.BottomDist(rTab.getFrameArea(), aRectFnSet.GetPrtBottom(*rTab.GetUpper()));
-    if ( nDistanceToUpperPrtBottom < 0 || !rTab.DoesObjsFit() )
+    // tdf#125685 ignore footnotes that are anchored in follow-table of this
+    // table - if split is successful they move to the next page/column anyway
+    assert(rTab.GetFollow() == rFollowLine.GetUpper());
+    SwTwips nFollowFootnotes(0);
+    // actually there should always be a boss frame, except if "this" isn't
+    // connected to a page yet; not sure if that can happen
+    if (SwFootnoteBossFrame const*const pBoss = rTab.FindFootnoteBossFrame())
+    {
+        if (SwFootnoteContFrame const*const pCont = pBoss->FindFootnoteCont())
+        {
+            for (SwFootnoteFrame const* pFootnote = static_cast<SwFootnoteFrame const*>(pCont->Lower());
+                 pFootnote != nullptr;
+                 pFootnote = static_cast<SwFootnoteFrame const*>(pFootnote->GetNext()))
+            {
+                SwContentFrame const*const pAnchor = pFootnote->GetRef();
+                SwTabFrame const* pTab = pAnchor->FindTabFrame();
+                if (pTab)
+                {
+                    while (pTab->GetUpper()->IsInTab())
+                    {
+                        pTab = pTab->GetUpper()->FindTabFrame();
+                    }
+                    // TODO currently do this only for top-level tables?
+                    // otherwise would need to check rTab's follow and any upper table's follow?
+                    if (pTab == rTab.GetFollow())
+                    {
+                        nFollowFootnotes += aRectFnSet.GetHeight(pFootnote->getFrameArea());
+                    }
+                }
+            }
+        }
+    }
+    if (nDistanceToUpperPrtBottom + nFollowFootnotes < 0 || !rTab.DoesObjsFit())
         bRet = false;
 
     // 2. Check if each cell in the last line has at least one content frame.