sw: avoid updating redlines to be empty in Overwrite()

The problem is that SwIndexReg::Update will correct a 1-character
redline in the middle of the newly-inserted part of the overwrite string
into a 0-length redline, which then a later SwTextNode::Update() will
correct in such a way that the whole thing becomes unsorted.

Just delete redlines in the entire overwrite range, which should help;
the aPam actually deletes them in the *last* character only which
seems rather unintentional anyway.

Change-Id: I61b6b312998e0779651d30f636312ef13556428c

sw/source/core/doc/DocumentContentOperationsManager.cxx

@@ -2357,8 +2357,12 @@ bool DocumentContentOperationsManager::MoveAndJoin( SwPaM& rPaM, SwPosition& rPo
     return bRet;
 }
 
+// Overwrite only uses the point of the PaM, the mark is ignored; characters
+// are replaced from point until the end of the node; at the end of the node,
+// characters are inserted.
 bool DocumentContentOperationsManager::Overwrite( const SwPaM &rRg, const OUString &rStr )
 {
+    assert(rStr.getLength());
     SwPosition& rPt = *const_cast<SwPosition*>(rRg.GetPoint());
     if( m_rDoc.GetAutoCorrExceptWord() )                  // Add to AutoCorrect
     {
@@ -2382,6 +2386,7 @@ bool DocumentContentOperationsManager::Overwrite( const SwPaM &rRg, const OUStri
                                 ? pNode->GetpSwpHints()->Count() : 0;
     SwDataChanged aTmp( rRg );
     SwIndex& rIdx = rPt.nContent;
+    sal_Int32 const nActualStart(rIdx.GetIndex());
     sal_Int32 nStart = 0;
 
     bool bOldExpFlg = pNode->IsIgnoreDontExpand();
@@ -2443,14 +2448,14 @@ bool DocumentContentOperationsManager::Overwrite( const SwPaM &rRg, const OUStri
     if (!m_rDoc.GetIDocumentUndoRedo().DoesUndo() &&
         !m_rDoc.getIDocumentRedlineAccess().IsIgnoreRedline() && !m_rDoc.getIDocumentRedlineAccess().GetRedlineTable().empty())
     {
-        SwPaM aPam( rPt.nNode, nStart, rPt.nNode, rPt.nContent.GetIndex() );
+        SwPaM aPam(rPt.nNode, nActualStart, rPt.nNode, rPt.nContent.GetIndex());
         m_rDoc.getIDocumentRedlineAccess().DeleteRedline( aPam, true, USHRT_MAX );
     }
     else if( m_rDoc.getIDocumentRedlineAccess().IsRedlineOn() )
     {
         // FIXME: this redline is WRONG: there is no DELETE, and the skipped
         // characters are also included in aPam
-        SwPaM aPam( rPt.nNode, nStart, rPt.nNode, rPt.nContent.GetIndex() );
+        SwPaM aPam(rPt.nNode, nActualStart, rPt.nNode, rPt.nContent.GetIndex());
         m_rDoc.getIDocumentRedlineAccess().AppendRedline( new SwRangeRedline( nsRedlineType_t::REDLINE_INSERT, aPam ), true);
     }
 

sw/source/core/doc/DocumentRedlineManager.cxx

@@ -82,6 +82,8 @@ using namespace com::sun::star;
             for(SwRangeRedline* j : rTable)
             {
                 // check for empty redlines
+                // note: these can destroy sorting in SwTextNode::Update()
+                // if there's another one wihout mark on the same pos.
                 OSL_ENSURE( ( *(j->GetPoint()) != *(j->GetMark()) ) ||
                             ( j->GetContentIdx() != nullptr ),
                             ERROR_PREFIX "empty redline" );