sw: fix undefined casts of SwTxtInputFld

... as reported by sberg via UBSan in CppunitTest_sw_mailmerge:

> sw/source/core/txtnode/thints.cxx:3207:38: runtime error: downcast of address 0x000003cadcb0 which does not point to an object of type 'SwTxtAttrNesting'
> 0x000003cadcb0: note: object is of type 'SwTxtInputFld'
> #0 in SwpHints::TryInsertHint(SwTxtAttr*, SwTxtNode&, unsigned short) sw/source/core/txtnode/thints.cxx:3207:13
> #1 in SwTxtNode::InsertHint(SwTxtAttr*, unsigned short) sw/source/core/txtnode/thints.cxx:1583:25
> #2 in SwTxtNode::SetAttr(SfxItemSet const&, int, int, unsigned short) sw/source/core/txtnode/thints.cxx:1943:39
> #3 in SwRegHistory::InsertItems(SfxItemSet const&, int, int, unsigned short) sw/source/core/undo/rolbck.cxx:1390:28
> #4 in (anonymous namespace)::lcl_InsAttr(SwDoc*, SwPaM const&, SfxItemSet const&, unsigned short, SwUndoAttr*, bool) sw/source/core/doc/DocumentContentOperationsManager.cxx:1169:28
> #5 in sw::DocumentContentOperationsManager::InsertPoolItem(SwPaM const&, SfxPoolItem const&, unsigned short, bool) sw/source/core/doc/DocumentContentOperationsManager.cxx:3041:23
> #6 in SwXTextField::attach(com::sun::star::uno::Reference<com::sun::star::text::XTextRange> const&) sw/source/core/unocore/unofield.cxx:1966:13 > #7 in non-virtual thunk to SwXTextField::attach(com::sun::star::uno::Reference<com::sun::star::text::XTextRange> const&) sw/source/core/unocore/unofield.cxx:2061:1

The SwTxtInputFld is unusual because it's both a field and has a range;
let's try to use virtual inheritance to inherit both from
SwTxtFld and SwTxtAttrNesting.  Sadly requires dynamic_cast everywhere.

Change-Id: I69f834d2b78ef7cdaac1f554bd80711084efcd02

1 files changed, 4 insertions, 5 deletions

diff --git a/sw/inc/txtfld.hxx b/sw/inc/txtfld.hxx
index 9758bd28ce3c..946a4bbfa916 100644
--- a/sw/inc/txtfld.hxx
+++ b/sw/inc/txtfld.hxx
@@ -27,7 +27,7 @@
 class SwPaM;
 class SwTxtNode;
 
-class SwTxtFld : public SwTxtAttr
+class SwTxtFld : public virtual SwTxtAttr
 {
     mutable OUString m_aExpand; // only used to determine, if field content is changing in <ExpandTxtFld()>
     SwTxtNode * m_pTxtNode;
@@ -73,7 +73,9 @@ public:
 
 };
 
-class SwTxtInputFld : public SwTxtFld
+class SwTxtInputFld
+    : public SwTxtAttrNesting
+    , public SwTxtFld
 {
 public:
     SwTxtInputFld(
@@ -84,8 +86,6 @@ public:
 
     virtual ~SwTxtInputFld();
 
-    virtual sal_Int32* GetEnd() SAL_OVERRIDE;
-
     void LockNotifyContentChange();
     void UnlockNotifyContentChange();
     virtual void NotifyContentChange( SwFmtFld& rFmtFld ) SAL_OVERRIDE;
@@ -96,7 +96,6 @@ public:
     void UpdateFieldContent();
 
 private:
-    sal_Int32 m_nEnd;
 
     bool m_bLockNotifyContentChange;
 };