sw/qa/extras/layout/data/tdf170477.docx |binary
 sw/qa/extras/layout/layout6.cxx         |    7 +++++++
 sw/source/core/layout/tabfrm.cxx        |   27 +++++++++++++++++++++++++--
 3 files changed, 32 insertions(+), 2 deletions(-)

New commits:
commit a5832581691c3532f24d754ed0488e7df43d82c0
Author:     Mike Kaganski <[email protected]>
AuthorDate: Mon Jan 26 10:46:04 2026 +0500
Commit:     Mike Kaganski <[email protected]>
CommitDate: Mon Jan 26 10:25:57 2026 +0100

    tdf#170477: detect MoveFwd oscillation in SwTabFrame::MakeAll
    
    In the specific bug document, some constellation of factors created
    the case where the last inner floating table tries to move forward,
    in the process creates a split fly on the same page (subject to move
    forward later, when outer table formats), moves to it (leaving the
    old fly empty), which recreates the same layout as before; and that
    oscillated infinitely.
    
    The fix implemented here is to detect when MoveFwd call created the
    described situation, and then use SwLayouter::InsertMovedFwdFrame
    to break the oscillation.
    
    I was not able to reproduce this problem anew; test document was
    simplified from the original, with the aim to minimize instability
    (but still, the resulting layout in Writer differs from Word's,
    which makes the test likely to stop testing the intended code path
    in the future - sigh).
    
    Change-Id: Iaa796a169cb9f97d5a6b3dd7ebf1cf5b726ca568
    Reviewed-on: https://gerrit.libreoffice.org/c/core/+/198116
    Reviewed-by: Mike Kaganski <[email protected]>
    Tested-by: Jenkins

diff --git a/sw/qa/extras/layout/data/tdf170477.docx 
b/sw/qa/extras/layout/data/tdf170477.docx
new file mode 100644
index 000000000000..646d7191c92d
Binary files /dev/null and b/sw/qa/extras/layout/data/tdf170477.docx differ
diff --git a/sw/qa/extras/layout/layout6.cxx b/sw/qa/extras/layout/layout6.cxx
index 8f11933f4cd3..0bca86f1d7f0 100644
--- a/sw/qa/extras/layout/layout6.cxx
+++ b/sw/qa/extras/layout/layout6.cxx
@@ -2050,6 +2050,13 @@ CPPUNIT_TEST_FIXTURE(SwLayoutWriter6, 
testTdf170381_split_float_table_in_float_t
         assertCellLines(2, r + 1, page2cells[r]);
 }
 
+CPPUNIT_TEST_FIXTURE(SwLayoutWriter6, testTdf170477)
+{
+    // This document must not hang on layout:
+    createSwDoc("tdf170477.docx");
+    calcLayout();
+}
+
 } // end of anonymous namespace
 
 CPPUNIT_PLUGIN_IMPLEMENT();
diff --git a/sw/source/core/layout/tabfrm.cxx b/sw/source/core/layout/tabfrm.cxx
index f37ea940b18e..f6cd00b56e7a 100644
--- a/sw/source/core/layout/tabfrm.cxx
+++ b/sw/source/core/layout/tabfrm.cxx
@@ -3274,6 +3274,7 @@ void SwTabFrame::MakeAll(vcl::RenderContext* 
pRenderContext)
 
         // #i29771# Reset bTryToSplit flag on change of upper
         const SwFrame* pOldUpper = GetUpper();
+        const SwPageFrame* pOldUpperPage = nullptr;
 
         //Let's see if we find some place anywhere...
         if (!bMovedFwd)
@@ -3288,6 +3289,7 @@ void SwTabFrame::MakeAll(vcl::RenderContext* 
pRenderContext)
                     // If the anchor of the split has a previous frame, 
MoveFwd() is allowed to move
                     // forward.
                     bMoveAlways = true;
+                    pOldUpperPage = pFlyFrame->FindPageFrame();
                 }
             }
             // don't make the effort to move fwd if its known
@@ -3301,8 +3303,29 @@ void SwTabFrame::MakeAll(vcl::RenderContext* 
pRenderContext)
         // #i29771# Reset bSplitError flag on change of upper
         if ( GetUpper() != pOldUpper )
         {
-            bTryToSplit = true;
-            nUnSplitted = 5;
+            bool bResetSplit = true;
+            if (GetUpper() && GetUpper()->IsFlyFrame() && pOldUpperPage
+                && GetUpper()->FindPageFrame() == pOldUpperPage
+                && static_cast<const 
SwFlyFrame*>(GetUpper())->IsFlySplitAllowed())
+            {
+                // MoveFwd created a split (follow) fly on the same page, that 
was intended to move
+                // to the next page together with its anchor. Then the content 
was moved to the new
+                // fly, and the old fly became empty; it called its 
DelEmpty(). The new fly is now
+                // basically a copy of the old one; move to the next page and 
prevent oscillation.
+                SwTextFrame* pAnchor = 
static_cast<SwFlyFrame*>(GetUpper())->FindAnchorCharFrame();
+                if (pAnchor)
+                {
+                    bResetSplit = false;
+                    SwPageFrame* pPage = pAnchor->FindPageFrame();
+                    
SwLayouter::InsertMovedFwdFrame(pPage->GetFormat()->GetDoc(), *pAnchor,
+                                                    pPage->GetPhyPageNum() + 
1);
+                }
+            }
+            if (bResetSplit)
+            {
+                bTryToSplit = true;
+                nUnSplitted = 5;
+            }
         }
 
         aRectFnSet.Refresh(*this);

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