Some work towards functioning remote debugging

 Fix gdb commands, state changes and signals emissions.
- There were some invalid gdb commands (e.g. "attach").
- There also were a number of unexplected state transitions.

src/plugins/debugger/gdb/remotegdbadapter.cpp

@@ -86,12 +86,12 @@ void RemoteGdbAdapter::startAdapter()
     gdbArgs.prepend(_("mi"));
     gdbArgs.prepend(_("-i"));
 
-    if (!m_engine->m_outputCollector.listen()) {
-        emit adapterStartFailed(tr("Cannot set up communication with child process: %1")
-                .arg(m_engine->m_outputCollector.errorString()));
-        return;
-    }
-    gdbArgs.prepend(_("--tty=") + m_engine->m_outputCollector.serverName());
+//    if (!m_engine->m_outputCollector.listen()) {
+//        emit adapterStartFailed(tr("Cannot set up communication with child process: %1")
+//                .arg(m_engine->m_outputCollector.errorString()));
+//        return;
+//    }
+//    gdbArgs.prepend(_("--tty=") + m_engine->m_outputCollector.serverName());
 
     if (!startParameters().workingDir.isEmpty())
         setWorkingDirectory(startParameters().workingDir);
@@ -193,20 +193,23 @@ void RemoteGdbAdapter::prepareInferior()
         m_engine->postCommand(_("-exec-arguments ")
             + startParameters().processArgs.join(_(" ")));
 
-    //qq->breakHandler()->setAllPending();
-    QFileInfo fi(startParameters().executable);
-    QString fileName = fi.absoluteFilePath();
-    m_engine->postCommand(_("-file-exec-and-symbols \"%1\"").arg(fileName),
-        CB(handleFileExecAndSymbols));
-
-    // works only for > 6.8
-    //postCommand(_("set target-async on"), CB(handleSetTargetAsync));
-    // a typical response on "old" gdb is:
-    // &"set target-async on\n"
-    //&"No symbol table is loaded.  Use the \"file\" command.\n"
-    //^error,msg="No symbol table is loaded.  Use the \"file\" command."
-    //postCommand(_("detach"));
-    //emit inferiorPreparationFailed(msg);
+    m_engine->postCommand(_("set target-async on"), CB(handleSetTargetAsync));
+}
+
+void RemoteGdbAdapter::handleSetTargetAsync(const GdbResponse &response)
+{
+    QTC_ASSERT(state() == InferiorPreparing, qDebug() << state());
+    if (response.resultClass == GdbResultDone) {
+        //qq->breakHandler()->setAllPending();
+        QFileInfo fi(startParameters().executable);
+        QString fileName = fi.absoluteFilePath();
+        m_engine->postCommand(_("-file-exec-and-symbols \"%1\"").arg(fileName),
+            CB(handleFileExecAndSymbols));
+    } else if (response.resultClass == GdbResultError) {
+        QString msg = tr("Adapter too old: does not support asynchronous mode.");
+        setState(InferiorPreparationFailed);
+        emit inferiorPreparationFailed(msg);
+    }
 }
 
 void RemoteGdbAdapter::handleFileExecAndSymbols(const GdbResponse &response)
@@ -214,9 +217,8 @@ void RemoteGdbAdapter::handleFileExecAndSymbols(const GdbResponse &response)
     QTC_ASSERT(state() == InferiorPreparing, qDebug() << state());
     if (response.resultClass == GdbResultDone) {
         //m_breakHandler->clearBreakMarkers();
-        QString channel = startParameters().remoteChannel;
-        m_engine->postCommand(_("target remote %1").arg(channel),
-            CB(handleTargetRemote));
+        m_engine->setState(InferiorPrepared);
+        emit inferiorPrepared();
     } else if (response.resultClass == GdbResultError) {
         QString msg = tr("Starting remote executable failed:\n");
         msg += __(response.data.findChild("msg").data());
@@ -227,10 +229,11 @@ void RemoteGdbAdapter::handleFileExecAndSymbols(const GdbResponse &response)
 
 void RemoteGdbAdapter::handleTargetRemote(const GdbResponse &record)
 {
-    QTC_ASSERT(state() == InferiorPreparing, qDebug() << state());
+    QTC_ASSERT(state() == InferiorStarting, qDebug() << state());
     if (record.resultClass == GdbResultDone) {
-        setState(InferiorPrepared);
-        emit inferiorPrepared();
+        // gdb server will stop the remote application itself.
+        debugMessage(_("INFERIOR STARTED"));
+        showStatusMessage(tr("Attached to stopped inferior."));
     } else if (record.resultClass == GdbResultError) {
         // 16^error,msg="hd:5555: Connection timed out."
         QString msg = tr("Connecting to remote server failed:\n");
@@ -243,21 +246,14 @@ void RemoteGdbAdapter::handleTargetRemote(const GdbResponse &record)
 void RemoteGdbAdapter::startInferior()
 {
     QTC_ASSERT(state() == InferiorStarting, qDebug() << state());
-    m_engine->postCommand(_("attach"), CB(handleFirstContinue));
-}
-
-void RemoteGdbAdapter::handleFirstContinue(const GdbResponse &record)
-{
-    QTC_ASSERT(state() == InferiorRunningRequested, qDebug() << state());
-    if (record.resultClass == GdbResultDone) {
-        setState(InferiorStopped);
-        debugMessage(_("INFERIOR STARTED"));
-        showStatusMessage(tr("Attached to stopped inferior."));
-    } else if (record.resultClass == GdbResultError) {
-        //QString msg = __(record.data.findChild("msg").data());
-        QString msg1 = tr("Connecting to remote server failed:\n");
-        emit inferiorStartFailed(msg1 + record.toString());
-    }
+    QString channel = startParameters().remoteChannel;
+
+    // "target remote" does three things:
+    //     (1) connects to the gdb server
+    //     (2) starts the remote application
+    //     (3) stops the remote application (early, e.g. in the dynamic linker)
+    m_engine->postCommand(_("target remote %1").arg(channel),
+        CB(handleTargetRemote));
 }
 
 void RemoteGdbAdapter::interruptInferior()

src/plugins/debugger/gdb/remotegdbadapter.h

@@ -71,11 +71,11 @@ private:
     Q_SLOT void readUploadStandardError();
     Q_SLOT void uploadProcError(QProcess::ProcessError error);
 
+    void handleSetTargetAsync(const GdbResponse &response);
     void handleFileExecAndSymbols(const GdbResponse &response);
+    void handleTargetRemote(const GdbResponse &response);
     void handleKill(const GdbResponse &response);
     void handleExit(const GdbResponse &response);
-    void handleTargetRemote(const GdbResponse &response);
-    void handleFirstContinue(const GdbResponse &response);
 
     Q_SLOT void handleGdbStarted();
     Q_SLOT void handleGdbError(QProcess::ProcessError error);