CDB: Improve expanding watch children.

... by storing the children information in an additional watchdata
source bit, thus being able to prove the model wrong in case it
claims children are needed.

src/plugins/debugger/cdb/cdbstackframecontext.cpp

@@ -49,7 +49,7 @@ typedef QList<WatchData> WatchDataList;
 inline bool truePredicate(const WatchData & /* whatever */) { return true; }
 inline bool falsePredicate(const WatchData & /* whatever */) { return false; }
 inline bool isDumperPredicate(const WatchData &wd)
-{ return wd.source == OwnerDumper; }
+{ return (wd.source & CdbStackFrameContext::SourceMask) == OwnerDumper; }
 
 static inline void debugWatchDataList(const QList<WatchData> &l, const char *why = 0)
 {
@@ -155,14 +155,14 @@ bool WatchHandleDumperInserter::expandPointerToDumpable(const WatchData &wd, QSt
         derefedWd.setAddress(hexAddrS);
         derefedWd.name = QString(QLatin1Char('*'));
         derefedWd.iname = wd.iname + QLatin1String(".*");
-        derefedWd.source = OwnerDumper;
+        derefedWd.source = OwnerDumper | CdbStackFrameContext::ChildrenKnownBit;
         const CdbDumperHelper::DumpResult dr = m_dumper->dumpType(derefedWd, true, OwnerDumper, &m_dumperResult, errorMessage);
         if (dr != CdbDumperHelper::DumpOk)
             break;
         // Insert the pointer item with 1 additional child + its dumper results
         // Note: formal arguments might already be expanded in the symbol group.
         WatchData ptrWd = wd;
-        ptrWd.source = OwnerDumper;
+        ptrWd.source = OwnerDumper | CdbStackFrameContext::ChildrenKnownBit;
         ptrWd.setHasChildren(true);
         ptrWd.setChildrenUnneeded();
         m_wh->insertData(ptrWd);
@@ -200,6 +200,9 @@ static inline void fixDumperResult(const WatchData &source,
     }
     if (size == 1)
         return;
+    // If the model queries the expanding item by pretending childrenNeeded=1,
+    // refuse the request as the children are already known
+    returned.source |= CdbStackFrameContext::ChildrenKnownBit;
     // Fix the children: If the address is missing, we cannot query any further.
     const QList<WatchData>::iterator wend = result->end();
     QList<WatchData>::iterator it = result->begin();
@@ -230,7 +233,7 @@ WatchHandleDumperInserter &WatchHandleDumperInserter::operator=(WatchData &wd)
         return *this;
     }
     // Expanded by internal dumper? : ok
-    if (wd.source == OwnerSymbolGroupDumper) {
+    if ((wd.source & CdbStackFrameContext::SourceMask) == OwnerSymbolGroupDumper) {
         m_wh->insertData(wd);
         return *this;
     }
@@ -312,7 +315,15 @@ bool CdbStackFrameContext::completeData(const WatchData &incompleteLocal,
     }
 
     // Expand artifical dumper items
-    if (incompleteLocal.source == OwnerDumper) {
+    if ((incompleteLocal.source & CdbStackFrameContext::SourceMask) == OwnerDumper) {
+        // If the model queries the expanding item by pretending childrenNeeded=1,
+        // refuse the request if the children are already known
+        if (incompleteLocal.state == WatchData::ChildrenNeeded && (incompleteLocal.source & CdbStackFrameContext::ChildrenKnownBit)) {
+            WatchData local = incompleteLocal;
+            local.setChildrenUnneeded();
+            wh->insertData(local);
+            return true;
+        }
         QList<WatchData> dumperResult;
         const CdbDumperHelper::DumpResult dr = m_dumper->dumpType(incompleteLocal, true, OwnerDumper, &dumperResult, errorMessage);
         if (dr == CdbDumperHelper::DumpOk) {

src/plugins/debugger/cdb/cdbstackframecontext.h

@@ -49,6 +49,9 @@ class CdbStackFrameContext
 {
     Q_DISABLE_COPY(CdbStackFrameContext)
 public:
+    // Mask bits for the source field of watch data.
+    enum { SourceMask = 0xFF, ChildrenKnownBit = 0x0100 };
+
     explicit CdbStackFrameContext(const QSharedPointer<CdbDumperHelper> &dumper,
                                   CdbSymbolGroupContext *symbolContext);
     ~CdbStackFrameContext();