fdo#63553: sw: fix copy/paste of cross references

If one of aIds or aDestIds contains nSeqNo then adding an identity
mapping for it will actually re-define a previous mapping.  Likely this
can only happen when clipboard document is the source.

(regression from 44f971506c0ed37928c48e55d8007f24b0c43a5f)

(also it looks like 4b0b0a5b3045902d9a6b95510ec30a3027181e29 has subtly
 changed what the "else" branch does when it is erroneously taken -
 results are differently wrong)

Change-Id: I34e2979e45cffeb62ebf3d7b3e5ac6d2afff0c2b
(cherry picked from commit bb665affbd8870652ade3951d626d76e99143f67)
Reviewed-on: https://gerrit.libreoffice.org/7730
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>
(cherry picked from commit 139342a9ad5995058081a47a24818b14581735a5)
Reviewed-on: https://gerrit.libreoffice.org/7740
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

1 files changed, 13 insertions, 5 deletions

diff --git a/sw/source/core/fields/reffld.cxx b/sw/source/core/fields/reffld.cxx
index 4c668b04ea20..ba0e4bb528d1 100644
--- a/sw/source/core/fields/reffld.cxx
+++ b/sw/source/core/fields/reffld.cxx
@@ -997,7 +997,7 @@ void _RefIdsMap::Init( SwDoc& rDoc, SwDoc& rDestDoc, bool bField )
         for ( std::set<sal_uInt16>::iterator pIt = aDstIds.begin(); pIt != aDstIds.end(); ++pIt )
             AddId( GetFirstUnusedId(aIds), *pIt );
 
-        // Change the Sequence number of all the SetExp fields in the destination document
+        // Change the Sequence number of all SetExp fields in the source document
         SwFieldType* pType = rDoc.GetFldType( RES_SETEXPFLD, aName, false );
         if( pType )
         {
@@ -1051,16 +1051,24 @@ void _RefIdsMap::Check( SwDoc& rDoc, SwDoc& rDestDoc, SwGetRefField& rFld,
 {
     Init( rDoc, rDestDoc, bField);
 
-    // dann teste mal, ob die Nummer schon vergeben ist
-    // oder ob eine neue bestimmt werden muss.
     sal_uInt16 nSeqNo = rFld.GetSeqNo();
-    if( aIds.count( nSeqNo ) && aDstIds.count( nSeqNo ))
+
+    // Check if the number is used in both documents
+    // Note: For fields, aIds contains both the ids of SetExp from rDestDoc
+    // and the targets of the already remapped ones from rDoc.
+    // It is possible that aDstIds contains numbers that aIds does not contain!
+    // For example, copying a selection to clipboard that does not contain
+    // the first SwSetExpField will result in id 0 missing, then pasting that
+    // into empty document gives a mapping 1->0 ... N->N-1 (fdo#63553).
+    if (aIds.count(nSeqNo) || aDstIds.count(nSeqNo))
     {
         // Number already taken, so need a new one.
         if( sequencedIds.count(nSeqNo) )
             rFld.SetSeqNo( sequencedIds[nSeqNo] );
         else
         {
+            assert(!bField || !aDstIds.count(nSeqNo)); // postcond of Init
+
             sal_uInt16 n = GetFirstUnusedId( aIds );
 
             // die neue SeqNo eintragen, damit die "belegt" ist
@@ -1082,7 +1090,7 @@ void _RefIdsMap::Check( SwDoc& rDoc, SwDoc& rDestDoc, SwGetRefField& rFld,
     }
     else
     {
-        AddId( nSeqNo, nSeqNo );
+        AddId( nSeqNo, nSeqNo ); // this requires that nSeqNo is unused in both!
     }
 }