fdo#81945 [DOCX] Round Tripped file corrupted due to nested SDTs

Original File contains two separate SDTs which are getting
nested during RT as follows:-

sdtStart [MARK] rPr [MARK] sdtEND RunSTART
          ==PREPEND==> sdtStart [MARK] sdtEND RunSTART rPr RunEND
Now Another SDT starts
sdtStart [MARK] sdtEND RunSTART rPr RunEND [MARK] sdtStart
          ==PREPEND==>  sdtStart [MARK] sdtStart sdtEND RunSTART rPr RunEND

So, in such cases wait before closing the earlier sdt, to avoid nesting. Thus the [MARK]
can be retained in the corrrect position, to start the new SDT and end the earlier SDT.

Reviewed on:
	https://gerrit.libreoffice.org/10803

Change-Id: Ia86f94c0587a5d44ab23391ea9ac38f86b5dd250

sw/qa/extras/ooxmlexport/ooxmlfieldexport.cxx

@@ -582,6 +582,15 @@ DECLARE_OOXMLEXPORT_TEST(testEditTime, "fdo81341.docx")
     }
 }
 
+DECLARE_OOXMLEXPORT_TEST(testFdo81945, "fdo81945.docx")
+{
+    xmlDocPtr pXmlDoc = parseExport("word/document.xml");
+    if (!pXmlDoc)
+        return;
+
+    assertXPath(pXmlDoc, "//w:sdt//w:sdt", 0);
+}
+
 #endif
 
 CPPUNIT_PLUGIN_IMPLEMENT();

sw/source/filter/ww8/docxattributeoutput.cxx

@@ -1004,11 +1004,18 @@ void DocxAttributeOutput::EndRun()
     // level down, to be able to prepend the actual run start attribute (just
     // before "postponed run start")
     m_pSerializer->mark(); // let's call it "actual run start"
+    bool bCloseEarlierSDT = false;
 
     if (m_bEndCharSdt)
     {
         // This is the common case: "close sdt before the current run" was requrested by the next run.
-        EndSdtBlock();
+
+        // if another sdt starts in this run, then wait
+        // as closing the sdt now, might cause nesting of sdts
+        if (m_nRunSdtPrToken > 0)
+            bCloseEarlierSDT = true;
+        else
+            EndSdtBlock();
         m_bEndCharSdt = false;
         m_bStartedCharSdt = false;
     }
@@ -1131,6 +1138,15 @@ void DocxAttributeOutput::EndRun()
         m_nRunSdtPrToken = 0;
         lcl_deleteAndResetTheLists( m_pRunSdtPrTokenChildren, m_pRunSdtPrDataBindingAttrs, m_aRunSdtPrAlias );
     }
+
+    if (bCloseEarlierSDT)
+    {
+        m_pSerializer->mark();
+        EndSdtBlock();
+        m_pSerializer->mergeTopMarks( sax_fastparser::MERGE_MARKS_PREPEND );
+        bCloseEarlierSDT = false;
+    }
+
     m_pSerializer->mergeTopMarks();
 
     WritePostponedMath();