Debugger: Fix Window grabbing on GDB

Needs to make namespace detection work without valid frame

Task-number: QTCREATORBUG-17326
Change-Id: Ia7c7017db4ef384d4f246e11a5601d01f4f366f1
Reviewed-by: hjk <hjk@qt.io>

share/qtcreator/debugger/gdbbridge.py

@@ -33,6 +33,7 @@ import os
 import os.path
 import sys
 import struct
+import tempfile
 import types
 
 from dumper import *
@@ -1023,27 +1024,21 @@ class Dumper(DumperBase):
         for objfile in gdb.objfiles():
             name = objfile.filename
             if name.find('/libQt5Core') >= 0:
+                fd, tmppath = tempfile.mkstemp()
+                os.close(fd)
+                cmd = 'maint print msymbols %s "%s"' % (tmppath, name)
+                symbols = gdb.execute(cmd, to_string = True)
                 ns = ''
-
-                # This only works when called from a valid frame.
-                try:
-                    cand = 'QArrayData::shared_null'
-                    symbol = gdb.lookup_symbol(cand)[0]
-                    if symbol:
-                        ns = symbol.name[:-len(cand)]
-                except:
-                    symbol = None
-
-                if symbol is None:
-                    try:
-                        # Some GDB 7.11.1 on Arch Linux.
-                        cand = 'QArrayData::shared_null[0]'
-                        val = gdb.parse_and_eval(cand)
-                        if val.type is not None:
-                            typeobj = val.type.unqualified()
-                            ns = typeobj.name[:-len('QArrayData')]
-                    except:
-                        pass
+                with open(tmppath) as f:
+                    for line in f:
+                        if line.find('msgHandlerGrabbed ') >= 0:
+                            # [11] b 0x7ffff683c000 _ZN4MynsL17msgHandlerGrabbedE
+                            # section .tbss Myns::msgHandlerGrabbed  qlogging.cpp
+                            ns = re.split('_ZN(\d*)(\w*)L17msgHandlerGrabbedE ', line)[2]
+                            if len(ns):
+                                ns += '::'
+                            break
+                os.remove(tmppath)
 
                 lenns = len(ns)
                 strns = ('%d%s' % (lenns - 2, ns[:lenns - 2])) if lenns else ''
@@ -1054,10 +1049,7 @@ class Dumper(DumperBase):
                     sym = '_ZN7QObject11customEventEP6QEvent'
                 self.qtCustomEventFunc = self.findSymbol(sym)
 
-                if lenns:
-                    sym = '_ZN%s7QObject11customEventEPNS_6QEventE@plt' % strns
-                else:
-                    sym = '_ZN7QObject11customEventEP6QEvent@plt'
+                sym += '@plt'
                 self.qtCustomEventPltFunc = self.findSymbol(sym)
 
                 sym = '_ZNK7%sQObject8propertyEPKc' % strns
@@ -1093,6 +1085,17 @@ class Dumper(DumperBase):
             cmd = 'set variable (%s)=%s' % (expr, value)
             gdb.execute(cmd)
 
+    def watchPoint(self, args):
+        ns = self.qtNamespace()
+        lenns = len(ns)
+        strns = ('%d%s' % (lenns - 2, ns[:lenns - 2])) if lenns else ''
+        sym = '_ZN%s12QApplication8widgetAtEii' % strns
+        expr = '%s(%s,%s)' % (sym, args['x'], args['y'])
+        res = self.parseAndEvaluate(expr)
+        p = 0 if res is None else res.pointer()
+        n = ("'%sQWidget'" % ns) if lenns else 'QWidget'
+        safePrint('{selected="0x%x",expr="(%s*)0x%x"}' % (p, n, p))
+
     def nativeDynamicTypeName(self, address, baseType):
         # Needed for Gdb13393 test.
         nativeType = self.lookupNativeType(baseType.name)
@@ -1361,7 +1364,6 @@ class Dumper(DumperBase):
 
     def profile1(self, args):
         '''Internal profiling'''
-        import tempfile
         import cProfile
         tempDir = tempfile.gettempdir() + '/bbprof'
         cProfile.run('theDumper.fetchVariables(%s)' % args, tempDir)

share/qtcreator/debugger/lldbbridge.py

@@ -1646,7 +1646,7 @@ class Dumper(DumperBase):
             result += ',data="%s %s"' % (insn.GetMnemonic(self.target),
                 insn.GetOperands(self.target))
             result += ',function="%s"' % functionName
-            rawData = insn.GetData(lldb.target).uint8s
+            rawData = insn.GetData(self.target).uint8s
             result += ',rawdata="%s"' % ' '.join(["%02x" % x for x in rawData])
             if comment:
                 result += ',comment="%s"' % self.hexencode(comment)
@@ -1678,6 +1678,20 @@ class Dumper(DumperBase):
         lhs.SetValueFromCString(value, error)
         self.reportResult(self.describeError(error), args)
 
+    def watchPoint(self, args):
+        self.reportToken(args)
+        ns = self.qtNamespace()
+        lenns = len(ns)
+        funcs = self.target.FindGlobalFunctions('.*QApplication::widgetAt', 2, 1)
+        func = funcs[1]
+        addr = func.GetFunction().GetStartAddress().GetLoadAddress(self.target)
+        expr = '((void*(*)(int,int))0x%x)' % addr
+        #expr = '%sQApplication::widgetAt(%s,%s)' % (ns, args['x'], args['y'])
+        res = self.parseAndEvaluate(expr)
+        p = 0 if res is None else res.pointer()
+        n = ns + 'QWidget'
+        self.reportResult('selected="0x%x",expr="(%s*)0x%x"' % (p, n, p), args)
+
     def createResolvePendingBreakpointsHookBreakpoint(self, args):
         bp = self.target.BreakpointCreateByName('qt_qmlDebugConnectorOpen')
         bp.SetOneShot(True)

src/plugins/debugger/debuggerprotocol.h

@@ -75,6 +75,23 @@ private:
     void argHelper(const char *name, const QByteArray &value);
 };
 
+class DebuggerCommandSequence
+{
+public:
+    DebuggerCommandSequence() {}
+    bool isEmpty() const { return m_commands.isEmpty(); }
+    bool wantContinue() const { return m_continue; }
+    const QList<DebuggerCommand> &commands() const { return m_commands; }
+    void append(const DebuggerCommand &cmd, bool wantContinue) {
+        m_commands.append(cmd);
+        m_continue = wantContinue;
+    }
+
+public:
+    QList<DebuggerCommand> m_commands;
+    bool m_continue = false;
+};
+
 // FIXME: rename into GdbMiValue
 class GdbMi
 {

src/plugins/debugger/gdb/gdbengine.cpp

@@ -138,18 +138,6 @@ static int &currentToken()
     return token;
 }
 
-static QString parsePlainConsoleStream(const DebuggerResponse &response)
-{
-    QString out = response.consoleStreamOutput;
-    // FIXME: proper decoding needed
-    if (out.endsWith("\\n"))
-        out.chop(2);
-    while (out.endsWith('\n') || out.endsWith(' '))
-        out.chop(1);
-    int pos = out.indexOf(" = ");
-    return out.mid(pos + 3);
-}
-
 static bool isMostlyHarmlessMessage(const QStringRef &msg)
 {
     return msg == "warning: GDB: Failed to set controlling terminal: "
@@ -229,7 +217,6 @@ GdbEngine::GdbEngine(const DebuggerRunParameters &startParameters)
     m_commandsDoneCallback = 0;
     m_stackNeeded = false;
     m_terminalTrap = startParameters.useTerminal;
-    m_temporaryStopPending = false;
     m_fullStartDone = false;
     m_systemDumpersLoaded = false;
     m_rerunPending = false;
@@ -905,10 +892,6 @@ void GdbEngine::runCommand(const DebuggerCommand &command)
     const int token = ++currentToken();
 
     DebuggerCommand cmd = command;
-    if (command.flags & PythonCommand) {
-        cmd.arg("token", token);
-        cmd.function = "python theDumper." + cmd.function + "(" + cmd.argsToPython() + ")";
-    }
 
     if (!stateAcceptsGdbCommands(state())) {
         showMessage(QString("NO GDB PROCESS RUNNING, CMD IGNORED: %1 %2")
@@ -916,7 +899,7 @@ void GdbEngine::runCommand(const DebuggerCommand &command)
         return;
     }
 
-    if (command.flags & RebuildBreakpointModel) {
+    if (cmd.flags & RebuildBreakpointModel) {
         ++m_pendingBreakpointRequests;
         PENDING_DEBUG("   BREAKPOINT MODEL:" << cmd.function
                       << "INCREMENTS PENDING TO" << m_pendingBreakpointRequests);
@@ -925,32 +908,44 @@ void GdbEngine::runCommand(const DebuggerCommand &command)
                       << "LEAVES PENDING BREAKPOINT AT" << m_pendingBreakpointRequests);
     }
 
-    if (!(command.flags & Discardable))
-        ++m_nonDiscardableCount;
-
-    if (command.flags & NeedsStop) {
+    if (cmd.flags & (NeedsTemporaryStop|NeedsFullStop)) {
         showMessage("RUNNING NEEDS-STOP COMMAND " + cmd.function);
+        const bool wantContinue = bool(cmd.flags & NeedsTemporaryStop);
+        cmd.flags &= ~(NeedsTemporaryStop|NeedsFullStop);
         if (state() == InferiorStopRequested) {
-            if (command.flags & LosesChild) {
+            if (cmd.flags & LosesChild) {
                 notifyInferiorIll();
                 return;
             }
             showMessage("CHILD ALREADY BEING INTERRUPTED. STILL HOPING.");
             // Calling shutdown() here breaks all situations where two
             // NeedsStop commands are issued in quick succession.
-        } else if (!m_temporaryStopPending && state() == InferiorRunOk) {
-            showStatusMessage(tr("Stopping temporarily"), 1000);
-            m_temporaryStopPending = true;
-            requestInterruptInferior();
+            m_onStop.append(cmd, wantContinue);
+            return;
         }
+        if (state() == InferiorRunOk) {
+            showStatusMessage(tr("Stopping temporarily"), 1000);
+            m_onStop.append(cmd, wantContinue);
+            requestInterruptInferior();
+            return;
+        }
+        showMessage("UNSAFE STATE FOR QUEUED COMMAND. EXECUTING IMMEDIATELY");
+    }
+
+    if (!(cmd.flags & Discardable))
+        ++m_nonDiscardableCount;
+
+    if (cmd.flags & PythonCommand) {
+        cmd.arg("token", token);
+        cmd.function = "python theDumper." + cmd.function + "(" + cmd.argsToPython() + ")";
     }
 
     QTC_ASSERT(m_gdbProc.state() == QProcess::Running, return);
 
     cmd.postTime = QTime::currentTime().msecsSinceStartOfDay();
     m_commandForToken[token] = cmd;
-    m_flagsForToken[token] = command.flags;
-    if (command.flags & ConsoleCommand)
+    m_flagsForToken[token] = cmd.flags;
+    if (cmd.flags & ConsoleCommand)
         cmd.function = "-interpreter-exec console \"" + cmd.function + '"';
     cmd.function = QString::number(token) + cmd.function;
     showMessage(cmd.function, LogInput);
@@ -1363,11 +1358,15 @@ void GdbEngine::handleStopResponse(const GdbMi &data)
         return;
     }
 
-    if (m_temporaryStopPending) {
-        showMessage("INTERNAL CONTINUE AFTER TEMPORARY STOP", LogMisc);
-        m_temporaryStopPending = false;
+    if (!m_onStop.isEmpty()) {
         notifyInferiorStopOk();
-        continueInferiorInternal();
+        showMessage("HANDLING QUEUED COMMANDS AFTER TEMPORARY STOP", LogMisc);
+        DebuggerCommandSequence seq = m_onStop;
+        m_onStop = DebuggerCommandSequence();
+        for (const DebuggerCommand &cmd : seq.commands())
+            runCommand(cmd);
+        if (seq.wantContinue())
+            continueInferiorInternal();
         return;
     }
 
@@ -1843,7 +1842,7 @@ void GdbEngine::shutdownInferior()
     DebuggerCommand cmd;
     cmd.function = QLatin1String(runParameters().closeMode == DetachAtClose ? "detach" : "kill");
     cmd.callback = CB(handleInferiorShutdown);
-    cmd.flags = NeedsStop|LosesChild;
+    cmd.flags = NeedsTemporaryStop|LosesChild;
     runCommand(cmd);
 }
 
@@ -1978,6 +1977,7 @@ bool GdbEngine::hasCapability(unsigned cap) const
         | WatchpointByAddressCapability
         | WatchpointByExpressionCapability
         | AddWatcherCapability
+        | AddWatcherWhileRunningCapability
         | WatchWidgetsCapability
         | ShowModuleSymbolsCapability
         | ShowModuleSectionsCapability
@@ -2559,7 +2559,7 @@ void GdbEngine::handleBreakInsert1(const DebuggerResponse &response, Breakpoint
             const GdbMi mainbkpt = response.data["bkpt"];
             bp.notifyBreakpointRemoveProceeding();
             DebuggerCommand cmd("-break-delete " + mainbkpt["number"].data(),
-                    NeedsStop | RebuildBreakpointModel);
+                    NeedsTemporaryStop | RebuildBreakpointModel);
             runCommand(cmd);
             bp.notifyBreakpointRemoveOk();
             return;
@@ -2586,14 +2586,14 @@ void GdbEngine::handleBreakInsert1(const DebuggerResponse &response, Breakpoint
         const int lineNumber = bp.lineNumber();
         DebuggerCommand cmd("trace \"" + GdbMi::escapeCString(fileName) + "\":"
                             + QString::number(lineNumber),
-                            NeedsStop | RebuildBreakpointModel);
+                            NeedsTemporaryStop | RebuildBreakpointModel);
         runCommand(cmd);
     } else {
         // Some versions of gdb like "GNU gdb (GDB) SUSE (6.8.91.20090930-2.4)"
         // know how to do pending breakpoints using CLI but not MI. So try
         // again with MI.
         DebuggerCommand cmd("break " + breakpointLocation2(bp.parameters()),
-                            NeedsStop | RebuildBreakpointModel);
+                            NeedsTemporaryStop | RebuildBreakpointModel);
         cmd.callback = [this, bp](const DebuggerResponse &r) { handleBreakInsert2(r, bp); };
         runCommand(cmd);
     }
@@ -2730,7 +2730,7 @@ void GdbEngine::insertBreakpoint(Breakpoint bp)
     const BreakpointParameters &data = bp.parameters();
 
     if (!data.isCppBreakpoint()) {
-        DebuggerCommand cmd("insertInterpreterBreakpoint", PythonCommand | NeedsStop);
+        DebuggerCommand cmd("insertInterpreterBreakpoint", PythonCommand | NeedsTemporaryStop);
         bp.addToCommand(&cmd);
         cmd.callback = [this, bp](const DebuggerResponse &r) { handleInsertInterpreterBreakpoint(r, bp); };
         runCommand(cmd);
@@ -2752,7 +2752,7 @@ void GdbEngine::insertBreakpoint(Breakpoint bp)
     } else if (type == BreakpointAtFork) {
         cmd.function = "catch fork";
         cmd.callback = handleCatch;
-        cmd.flags = NeedsStop | RebuildBreakpointModel;
+        cmd.flags = NeedsTemporaryStop | RebuildBreakpointModel;
         runCommand(cmd);
         // Another one...
         cmd.function = "catch vfork";
@@ -2789,7 +2789,7 @@ void GdbEngine::insertBreakpoint(Breakpoint bp)
         cmd.function += breakpointLocation(bp.parameters());
         cmd.callback = [this, bp](const DebuggerResponse &r) { handleBreakInsert1(r, bp); };
     }
-    cmd.flags = NeedsStop | RebuildBreakpointModel;
+    cmd.flags = NeedsTemporaryStop | RebuildBreakpointModel;
     runCommand(cmd);
 }
 
@@ -2838,7 +2838,7 @@ void GdbEngine::changeBreakpoint(Breakpoint bp)
         bp.notifyBreakpointChangeOk();
         return;
     }
-    cmd.flags = NeedsStop | RebuildBreakpointModel;
+    cmd.flags = NeedsTemporaryStop | RebuildBreakpointModel;
     runCommand(cmd);
 }
 
@@ -2860,7 +2860,7 @@ void GdbEngine::removeBreakpoint(Breakpoint bp)
         // We already have a fully inserted breakpoint.
         bp.notifyBreakpointRemoveProceeding();
         showMessage(QString("DELETING BP %1 IN %2").arg(br.id.toString()).arg(bp.fileName()));
-        DebuggerCommand cmd("-break-delete " + br.id.toString(), NeedsStop | RebuildBreakpointModel);
+        DebuggerCommand cmd("-break-delete " + br.id.toString(), NeedsTemporaryStop | RebuildBreakpointModel);
         runCommand(cmd);
 
         // Pretend it succeeds without waiting for response. Feels better.
@@ -2996,7 +2996,7 @@ void GdbEngine::requestModuleSymbols(const QString &modulePath)
         return;
     QString fileName = tf.fileName();
     tf.close();
-    DebuggerCommand cmd("maint print msymbols \"" + fileName + "\" " + modulePath, NeedsStop);
+    DebuggerCommand cmd("maint print msymbols \"" + fileName + "\" " + modulePath, NeedsTemporaryStop);
     cmd.callback = [modulePath, fileName](const DebuggerResponse &r) {
         handleShowModuleSymbols(r, modulePath, fileName);
     };
@@ -3006,7 +3006,7 @@ void GdbEngine::requestModuleSymbols(const QString &modulePath)
 void GdbEngine::requestModuleSections(const QString &moduleName)
 {
     // There seems to be no way to get the symbols from a single .so.
-    DebuggerCommand cmd("maint info section ALLOBJ", NeedsStop);
+    DebuggerCommand cmd("maint info section ALLOBJ", NeedsTemporaryStop);
     cmd.callback = [this, moduleName](const DebuggerResponse &r) {
         handleShowModuleSections(r, moduleName);
     };
@@ -3059,7 +3059,7 @@ void GdbEngine::reloadModules()
 
 void GdbEngine::reloadModulesInternal()
 {
-    runCommand({"info shared", NeedsStop, CB(handleModulesList)});
+    runCommand({"info shared", NeedsTemporaryStop, CB(handleModulesList)});
 }
 
 static QString nameFromPath(const QString &path)
@@ -3140,7 +3140,7 @@ void GdbEngine::reloadSourceFiles()
 {
     if ((state() == InferiorRunOk || state() == InferiorStopOk) && !m_sourcesListUpdating) {
         m_sourcesListUpdating = true;
-        DebuggerCommand cmd("-file-list-exec-source-files", NeedsStop);
+        DebuggerCommand cmd("-file-list-exec-source-files", NeedsTemporaryStop);
         cmd.callback = [this](const DebuggerResponse &response) {
             m_sourcesListUpdating = false;
             if (response.resultClass == ResultDone) {
@@ -3349,7 +3349,7 @@ void GdbEngine::createSnapshot()
         fileName = tf.fileName();
         tf.close();
         // This must not be quoted, it doesn't work otherwise.
-        DebuggerCommand cmd("gcore " + fileName, NeedsStop | ConsoleCommand);
+        DebuggerCommand cmd("gcore " + fileName, NeedsTemporaryStop | ConsoleCommand);
         cmd.callback = [this, fileName](const DebuggerResponse &r) { handleMakeSnapshot(r, fileName); };
         runCommand(cmd);
     } else {
@@ -3613,30 +3613,24 @@ void GdbEngine::assignValueInDebugger(WatchItem *item,
 
 void GdbEngine::watchPoint(const QPoint &pnt)
 {
-    QString x = QString::number(pnt.x());
-    QString y = QString::number(pnt.y());
-    runCommand({"print " + qtNamespace() + "QApplication::widgetAt(" + x + ',' + y + ')',
-                NeedsStop, CB(handleWatchPoint)});
+    DebuggerCommand cmd("watchPoint", PythonCommand|NeedsFullStop);
+    cmd.arg("x", pnt.x());
+    cmd.arg("y", pnt.y());
+    cmd.callback = CB(handleWatchPoint);
+    runCommand(cmd);
 }
 
 void GdbEngine::handleWatchPoint(const DebuggerResponse &response)
 {
     if (response.resultClass == ResultDone) {
-        // "$5 = (void *) 0xbfa7ebfc\n"
-        const QString ba = parsePlainConsoleStream(response);
-        const int pos0x = ba.indexOf("0x");
-        if (pos0x == -1) {
-            showStatusMessage(tr("Cannot read widget data: %1").arg(ba));
-        } else {
-            const QString addr = ba.mid(pos0x);
-            if (addr.toULongLong(0, 0)) { // Non-null pointer
-                const QString type = "::" + qtNamespace() + "QWidget";
-                const QString exp = QString("{%1}%2").arg(type).arg(addr);
-                watchHandler()->watchExpression(exp);
-            } else {
-                showStatusMessage(tr("Could not find a widget."));
-            }
-        }
+        GdbMi res;
+        res.fromString(response.consoleStreamOutput);
+        qulonglong addr = res["selected"].toAddress();
+        if (addr == 0)
+            showStatusMessage(tr("Could not find a widget."));
+        // Add the watcher entry nevertheless, as that's the place where
+        // the user expects visual feedback.
+        watchHandler()->watchExpression(res["expr"].data(), QString(), true);
     }
 }
 
@@ -3658,7 +3652,7 @@ public:
 void GdbEngine::changeMemory(MemoryAgent *agent, quint64 addr, const QByteArray &data)
 {
     Q_UNUSED(agent)
-    DebuggerCommand cmd("-data-write-memory 0x" + QString::number(addr, 16) + " d 1", NeedsStop);
+    DebuggerCommand cmd("-data-write-memory 0x" + QString::number(addr, 16) + " d 1", NeedsTemporaryStop);
     foreach (unsigned char c, data)
         cmd.function += ' ' + QString::number(uint(c));
     cmd.callback = CB(handleVarAssign);
@@ -3681,7 +3675,7 @@ void GdbEngine::fetchMemoryHelper(const MemoryAgentCookie &ac)
     DebuggerCommand cmd("-data-read-memory 0x"
                         + QString::number(ac.base + ac.offset, 16) + " x 1 1 "
                         + QString::number(ac.length),
-                        NeedsStop);
+                        NeedsTemporaryStop);
     cmd.callback = [this, ac](const DebuggerResponse &r) { handleFetchMemory(r, ac); };
     runCommand(cmd);
 }
@@ -4179,7 +4173,7 @@ void GdbEngine::resetInferior()
         foreach (QString command, commands.split('\n')) {
             command = command.trimmed();
             if (!command.isEmpty())
-                runCommand({command, ConsoleCommand | NeedsStop});
+                runCommand({command, ConsoleCommand | NeedsTemporaryStop});
         }
     }
     m_rerunPending = true;
@@ -4325,7 +4319,7 @@ void GdbEngine::handleAdapterCrashed(const QString &msg)
 
 void GdbEngine::createFullBacktrace()
 {
-    DebuggerCommand cmd("thread apply all bt full", NeedsStop | ConsoleCommand);
+    DebuggerCommand cmd("thread apply all bt full", NeedsTemporaryStop | ConsoleCommand);
     cmd.callback = [this](const DebuggerResponse &response) {
         if (response.resultClass == ResultDone) {
             Internal::openTextEditor("Backtrace $",

src/plugins/debugger/gdb/gdbengine.h

@@ -44,6 +44,8 @@
 #include <QTime>
 #include <QTimer>
 
+#include <functional>
+
 namespace Debugger {
 namespace Internal {
 
@@ -151,11 +153,13 @@ private: ////////// Gdb Command Management //////////
     enum GdbCommandFlag {
         NoFlags = 0,
         // The command needs a stopped inferior.
-        NeedsStop = 1,
+        NeedsTemporaryStop = 1,
         // No need to wait for the reply before continuing inferior.
         Discardable = 2,
         // Needs a dummy extra command to force GDB output flushing.
         NeedsFlush = 4,
+        // The command needs a stopped inferior and will stay stopped afterward.
+        NeedsFullStop = 8,
         // Callback expects ResultRunning instead of ResultDone.
         RunRequest = 16,
         // Callback expects ResultExit instead of ResultDone.
@@ -267,6 +271,7 @@ private: ////////// View & Data Stuff //////////
 
     void selectThread(ThreadId threadId) override;
     void activateFrame(int index) override;
+    void handleAutoContinueInferior();
 
     //
     // Breakpoint specific stuff
@@ -378,7 +383,7 @@ protected:
     void changeMemory(MemoryAgent *agent, quint64 addr, const QByteArray &data) override;
     void handleFetchMemory(const DebuggerResponse &response, MemoryAgentCookie ac);
 
-    virtual void watchPoint(const QPoint &) override;
+    void watchPoint(const QPoint &) override;
     void handleWatchPoint(const DebuggerResponse &response);
 
     void showToolTip();
@@ -420,10 +425,11 @@ protected:
     QString m_lastWinException;
     QString m_lastMissingDebugInfo;
     bool m_terminalTrap;
-    bool m_temporaryStopPending;
     bool usesExecInterrupt() const;
     bool usesTargetAsync() const;
 
+    DebuggerCommandSequence m_onStop;
+
     QHash<int, QString> m_scheduledTestResponses;
     QSet<int> m_testCases;
 

src/plugins/debugger/lldb/lldbengine.cpp

@@ -112,25 +112,34 @@ void LldbEngine::executeDebuggerCommand(const QString &command, DebuggerLanguage
     runCommand(cmd);
 }
 
-void LldbEngine::runCommand(const DebuggerCommand &cmd)
+void LldbEngine::runCommand(const DebuggerCommand &command)
 {
     if (m_lldbProc.state() != QProcess::Running) {
         // This can legally happen e.g. through a reloadModule()
         // triggered by changes in view visibility.
         showMessage(QString("NO LLDB PROCESS RUNNING, CMD IGNORED: %1 %2")
-            .arg(cmd.function).arg(state()));
+            .arg(command.function).arg(state()));
         return;
     }
     const int tok = ++currentToken();
-    DebuggerCommand command = cmd;
-    command.arg("token", tok);
+    DebuggerCommand cmd = command;
+    cmd.arg("token", tok);
     QString token = QString::number(tok);
-    QString function = command.function + "(" + command.argsToPython() + ")";
+    QString function = cmd.function + "(" + cmd.argsToPython() + ")";
     QString msg = token + function + '\n';
-    if (cmd.flags == LldbEngine::Silent)
+    if (cmd.flags == Silent)
         msg.replace(QRegularExpression("\"environment\":.[^]]*."), "<environment suppressed>");
+    if (cmd.flags == NeedsFullStop) {
+        cmd.flags &= ~NeedsFullStop;
+        if (state() == InferiorRunOk) {
+            showStatusMessage(tr("Stopping temporarily"), 1000);
+            m_onStop.append(cmd, false);
+            requestInterruptInferior();
+            return;
+        }
+    }
     showMessage(msg, LogInput);
-    m_commandForToken[currentToken()] = command;
+    m_commandForToken[currentToken()] = cmd;
     m_lldbProc.write("script theDumper." + function.toUtf8() + "\n");
 }
 
@@ -139,6 +148,22 @@ void LldbEngine::debugLastCommand()
     runCommand(m_lastDebuggableCommand);
 }
 
+void LldbEngine::watchPoint(const QPoint &pnt)
+{
+    DebuggerCommand cmd("watchPoint", NeedsFullStop);
+    cmd.arg("x", pnt.x());
+    cmd.arg("y", pnt.y());
+    cmd.callback = [this](const DebuggerResponse &response) {
+        qulonglong addr = response.data["selected"].toAddress();
+        if (addr == 0)
+            showStatusMessage(tr("Could not find a widget."));
+        // Add the watcher entry nevertheless, as that's the place where
+        // the user expects visual feedback.
+        watchHandler()->watchExpression(response.data["expr"].data(), QString(), true);
+    };
+    runCommand(cmd);
+}
+
 void LldbEngine::shutdownInferior()
 {
     QTC_ASSERT(state() == InferiorShutdownRequested, qDebug() << state());
@@ -907,11 +932,21 @@ void LldbEngine::handleStateNotification(const GdbMi &reportedState)
         m_continueAtNextSpontaneousStop = true;
     else if (newState == "stopped") {
         notifyInferiorSpontaneousStop();
-        if (m_continueAtNextSpontaneousStop) {
-            m_continueAtNextSpontaneousStop = false;
-            continueInferior();
+        if (m_onStop.isEmpty()) {
+            if (m_continueAtNextSpontaneousStop) {
+                m_continueAtNextSpontaneousStop = false;
+                continueInferior();
+            } else {
+                updateAll();
+            }
         } else {
-            updateAll();
+            showMessage("HANDLING QUEUED COMMANDS AFTER TEMPORARY STOP", LogMisc);
+            DebuggerCommandSequence seq = m_onStop;
+            m_onStop = DebuggerCommandSequence();
+            for (const DebuggerCommand &cmd : seq.commands())
+                runCommand(cmd);
+            if (seq.wantContinue())
+                continueInferior();
         }
     } else if (newState == "inferiorstopok") {
         notifyInferiorStopOk();
@@ -1098,8 +1133,8 @@ bool LldbEngine::hasCapability(unsigned cap) const
         | CreateFullBacktraceCapability
         | WatchpointByAddressCapability
         | WatchpointByExpressionCapability
-        | AddWatcherCapability
         | WatchWidgetsCapability
+        | AddWatcherCapability
         | ShowModuleSymbolsCapability
         | ShowModuleSectionsCapability
         | CatchCapability

src/plugins/debugger/lldb/lldbengine.h

@@ -64,7 +64,9 @@ public:
     enum LldbCommandFlag {
         NoFlags = 0,
         // Do not echo to log.
-        Silent = 1
+        Silent = 1,
+        // The command needs a stopped inferior and will stay stopped afterward.
+        NeedsFullStop = 8,
     };
 
 signals:
@@ -150,6 +152,9 @@ private:
     void runCommand(const DebuggerCommand &cmd) override;
     void debugLastCommand() override;
 
+    void watchPoint(const QPoint &) override;
+    void handleWatchPoint(const DebuggerResponse &response);
+
 private:
     DebuggerCommand m_lastDebuggableCommand;
 
@@ -163,6 +168,7 @@ private:
     QMap<QPointer<DisassemblerAgent>, int> m_disassemblerAgents;
 
     QHash<int, DebuggerCommand> m_commandForToken;
+    DebuggerCommandSequence m_onStop;
 
     // Console handling.
     void stubError(const QString &msg);

src/plugins/debugger/watchhandler.cpp

@@ -66,6 +66,7 @@
 #include <QMimeData>
 #include <QPainter>
 #include <QProcess>
+#include <QSet>
 #include <QTabWidget>
 #include <QTextEdit>
 #include <QTableWidget>
@@ -89,6 +90,7 @@ enum { debugModel = 0 };
 #define MODEL_DEBUG(s) do { if (debugModel) qDebug() << s; } while (0)
 
 static QMap<QString, int> theWatcherNames; // Keep order, QTCREATORBUG-12308.
+static QSet<QString> theTemporaryWatchers; // Used for 'watched widgets'.
 static int theWatcherCount = 0;
 static QHash<QString, int> theTypeFormats;
 static QHash<QString, int> theIndividualFormats;
@@ -430,6 +432,11 @@ public:
     void removeWatchItem(WatchItem *item);
     void inputNewExpression();
 
+    void grabWidget();
+    void ungrabWidget();
+    void timerEvent(QTimerEvent *event) override;
+    int m_grabWidgetTimerId = -1;
+
 public:
     WatchHandler *m_handler; // Not owned.
     DebuggerEngine *m_engine; // Not owned.
@@ -446,7 +453,6 @@ public:
 
     QSet<QString> m_expandedINames;
     QTimer m_requestUpdateTimer;
-    bool m_grabbing = false;
 
     QHash<QString, TypeInfo> m_reportedTypeInfo;
     QHash<QString, DisplayFormats> m_reportedTypeFormats; // Type name -> Dumper Formats
@@ -1067,13 +1073,6 @@ bool WatchModel::setData(const QModelIndex &idx, const QVariant &value, int role
             return true;
         }
 
-        if (ev.as<QMouseEvent>(QEvent::MouseButtonPress)) {
-            m_grabbing = false;
-            ev.view()->releaseMouse();
-            m_engine->watchPoint(ev.globalPos());
-            return true;
-        }
-
         if (ev.as<QMouseEvent>(QEvent::MouseButtonDblClick)) {
             if (item && !item->parent()) { // if item is the invisible root item
                 inputNewExpression();
@@ -1268,6 +1267,46 @@ static QString variableToolTip(const QString &name, const QString &type, quint64
           WatchModel::tr("<i>%1</i> %2").arg(type, name);
 }
 
+void WatchModel::grabWidget()
+{
+   qApp->setOverrideCursor(Qt::CrossCursor);
+   m_grabWidgetTimerId = startTimer(30);
+   ICore::mainWindow()->grabMouse();
+}
+
+void WatchModel::timerEvent(QTimerEvent *event)
+{
+    if (event->timerId() == m_grabWidgetTimerId) {
+        QPoint pnt = QCursor::pos();
+        Qt::KeyboardModifiers mods = QApplication::queryKeyboardModifiers();
+        QString msg;
+        if (mods == Qt::NoModifier) {
+            msg = tr("Press Ctrl to select widget at (%1, %2). "
+                     "Press any other keyboard modifier to stop selection.")
+                        .arg(pnt.x()).arg(pnt.y());
+        } else {
+            if (mods == Qt::CTRL) {
+                msg = tr("Selecting widget at (%1, %2).").arg(pnt.x()).arg(pnt.y());
+                m_engine->watchPoint(pnt);
+            } else {
+                msg = tr("Selection aborted.");
+            }
+            ungrabWidget();
+        }
+        showMessage(msg, StatusBar);
+    } else {
+        WatchModelBase::timerEvent(event);
+    }
+}
+
+void WatchModel::ungrabWidget()
+{
+    ICore::mainWindow()->releaseMouse();
+    qApp->restoreOverrideCursor();
+    killTimer(m_grabWidgetTimerId);
+    m_grabWidgetTimerId = -1;
+}
+
 int WatchModel::memberVariableRecursion(WatchItem *item,
                                         const QString &name,
                                         quint64 start, quint64 end,
@@ -1608,10 +1647,9 @@ bool WatchModel::contextMenuEvent(const ItemViewEvent &ev)
               canRemoveWatches && !m_handler->watchedExpressions().isEmpty(),
               [this] { clearWatches(); });
 
-// FIXME:
-//    addAction(menu, tr("Select Widget to Add into Expression Evaluator"),
-//              canHandleWatches && canInsertWatches && m_engine->hasCapability(WatchWidgetsCapability),
-//              [this, ev] { ev.view()->grabMouse(Qt::CrossCursor); m_grabbing = true; });
+    addAction(menu, tr("Select Widget to Add into Expression Evaluator"),
+              state == InferiorRunOk && m_engine->hasCapability(WatchWidgetsCapability),
+              [this] { grabWidget(); });
 
     menu->addSeparator();
     menu->addMenu(createFormatMenu(item));
@@ -1901,6 +1939,9 @@ void WatchHandler::cleanup()
 {
     m_model->m_expandedINames.clear();
     theWatcherNames.remove(QString());
+    for (const QString &exp : theTemporaryWatchers)
+        theWatcherNames.remove(exp);
+    theTemporaryWatchers.clear();
     saveWatchers();
     m_model->reinitialize();
     emit m_model->updateFinished();
@@ -2080,13 +2121,15 @@ QString WatchHandler::watcherName(const QString &exp)
 }
 
 // If \a name is empty, \a exp will be used as name.
-void WatchHandler::watchExpression(const QString &exp, const QString &name)
+void WatchHandler::watchExpression(const QString &exp, const QString &name, bool temporary)
 {
     // Do not insert the same entry more then once.
     if (exp.isEmpty() || theWatcherNames.contains(exp))
         return;
 
     theWatcherNames[exp] = theWatcherCount++;
+    if (temporary)
+        theTemporaryWatchers.insert(exp);
 
     auto item = new WatchItem;
     item->exp = exp;

src/plugins/debugger/watchhandler.h

@@ -66,7 +66,9 @@ public:
     WatchModelBase *model() const;
 
     void cleanup();
-    void watchExpression(const QString &exp, const QString &name = QString());
+    void grabWidget(QWidget *viewParent);
+    void watchExpression(const QString &exp, const QString &name = QString(),
+                         bool temporary = false);
     void updateWatchExpression(WatchItem *item, const QString &newExp);
     void watchVariable(const QString &exp);