QbsProjectManager: Do not try to call qbs if there is no executable

Otherwise, we'll get warnings from QProcess.

Change-Id: Ibaa536729fa644583c8ddc7a2931ac0ee11c0c9e
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/plugins/qbsprojectmanager/qbsprofilemanager.cpp

@@ -247,7 +247,10 @@ QString QbsProfileManager::runQbsConfig(QbsConfigOp op, const QString &key, cons
         args << "--unset" << key;
         break;
     }
-    qbsConfig.start(QbsSettings::qbsExecutableFilePath().toString(), args);
+    const Utils::FilePath qbsExe = QbsSettings::qbsExecutableFilePath();
+    if (qbsExe.isEmpty() || !qbsExe.exists())
+        return {};
+    qbsConfig.start(qbsExe.toString(), args);
     if (!qbsConfig.waitForStarted(3000) || !qbsConfig.waitForFinished(5000)) {
         Core::MessageManager::write(tr("Failed run qbs config: %1").arg(qbsConfig.errorString()));
     } else if (qbsConfig.exitCode() != 0) {

src/plugins/qbsprojectmanager/qbssession.cpp

@@ -219,7 +219,12 @@ void QbsSession::initialize()
     });
     connect(d->packetReader, &PacketReader::packetReceived, this, &QbsSession::handlePacket);
     d->state = State::Initializing;
-    d->qbsProcess->start(QbsSettings::qbsExecutableFilePath().toString(), {"session"});
+    const FilePath qbsExe = QbsSettings::qbsExecutableFilePath();
+    if (qbsExe.isEmpty() || !qbsExe.exists()) {
+        QTimer::singleShot(0, this, [this] { setError(Error::QbsFailedToStart); });
+        return;
+    }
+    d->qbsProcess->start(qbsExe.toString(), {"session"});
 }
 
 void QbsSession::sendQuitPacket()

src/plugins/qbsprojectmanager/qbssettings.cpp

@@ -159,8 +159,11 @@ public:
 private:
     static QString getQbsVersion()
     {
+        const FilePath qbsExe = QbsSettings::qbsExecutableFilePath();
+        if (qbsExe.isEmpty() || !qbsExe.exists())
+            return tr("Failed to retrieve version.");
         QProcess qbsProc;
-        qbsProc.start(QbsSettings::qbsExecutableFilePath().toString(), {"--version"});
+        qbsProc.start(qbsExe.toString(), {"--version"});
         if (!qbsProc.waitForStarted(3000) || !qbsProc.waitForFinished(5000)
                 || qbsProc.exitCode() != 0) {
             return tr("Failed to retrieve version.");

src/plugins/qbsprojectmanager/qbssettings.h

@@ -48,6 +48,7 @@ public:
     static QbsSettings &instance();
 
     static Utils::FilePath qbsExecutableFilePath();
+    static bool hasQbsExecutable();
     static QString defaultInstallDirTemplate();
     static bool useCreatorSettingsDirForQbs();
     static QString qbsSettingsBaseDir();