Clean up legacy content from Qt 5's QProcess::setupChildProcess()

We needed a derived class because in Qt 5 we needed to override the
setupChildProcess() virtual. Now have setChildProcessModifier(). The
actual subclassing was removed in a prior commit; this merely cleans
stuff up.

Drive-by fix the arguments to setpgid: processId() always returns 0 in
the child process.

Change-Id: Icfe44ecf285a480fafe4fffd174d1073c0e1ddc3
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/libs/utils/launcherinterface.cpp

@@ -21,20 +21,6 @@
 namespace Utils {
 namespace Internal {
 
-class LauncherProcess : public QProcess
-{
-public:
-    LauncherProcess(QObject *parent) : QProcess(parent)
-    {
-#ifdef Q_OS_UNIX
-        setChildProcessModifier([this] {
-            const auto pid = static_cast<pid_t>(processId());
-            setpgid(pid, pid);
-        });
-#endif
-    }
-};
-
 static QString launcherSocketName()
 {
     return TemporaryDirectory::masterDirectoryPath()
@@ -64,7 +50,7 @@ signals:
 private:
     QLocalServer * const m_server;
     Internal::LauncherSocket *const m_socket;
-    Internal::LauncherProcess *m_process = nullptr;
+    QProcess *m_process = nullptr;
     QString m_pathToLauncher;
 };
 
@@ -89,12 +75,18 @@ void LauncherInterfacePrivate::doStart()
         emit errorOccurred(m_server->errorString());
         return;
     }
-    m_process = new LauncherProcess(this);
+    m_process = new QProcess(this);
     connect(m_process, &QProcess::errorOccurred, this, &LauncherInterfacePrivate::handleProcessError);
     connect(m_process, &QProcess::finished,
             this, &LauncherInterfacePrivate::handleProcessFinished);
     connect(m_process, &QProcess::readyReadStandardError,
             this, &LauncherInterfacePrivate::handleProcessStderr);
+#ifdef Q_OS_UNIX
+    m_process->setChildProcessModifier([] {
+        setpgid(0, 0);
+    });
+#endif
+
     m_process->start(launcherFilePath(), QStringList(m_server->fullServerName()));
 }
 

src/libs/utils/processutils.cpp

@@ -107,7 +107,18 @@ ProcessHelper::ProcessHelper(QObject *parent)
     : QProcess(parent), m_processStartHandler(this)
 {
 #if defined(Q_OS_UNIX)
-    setChildProcessModifier([this] { setupChildProcess_impl(); });
+    setChildProcessModifier([this] {
+        // nice value range is -20 to +19 where -20 is highest, 0 default and +19 is lowest
+        if (m_lowPriority) {
+            errno = 0;
+            if (::nice(5) == -1 && errno != 0)
+                perror("Failed to set nice value");
+        }
+
+        // Disable terminal by becoming a session leader.
+        if (m_unixTerminalDisabled)
+            setsid();
+    });
 #endif
 }
 
@@ -153,20 +164,4 @@ void ProcessHelper::interruptProcess(QProcess *process)
         ProcessHelper::interruptPid(process->processId());
 }
 
-void ProcessHelper::setupChildProcess_impl()
-{
-#if defined Q_OS_UNIX
-    // nice value range is -20 to +19 where -20 is highest, 0 default and +19 is lowest
-    if (m_lowPriority) {
-        errno = 0;
-        if (::nice(5) == -1 && errno != 0)
-            perror("Failed to set nice value");
-    }
-
-    // Disable terminal by becoming a session leader.
-    if (m_unixTerminalDisabled)
-        setsid();
-#endif
-}
-
 } // namespace Utils

src/libs/utils/processutils.h

@@ -50,7 +50,6 @@ public:
 
 private:
     void terminateProcess();
-    void setupChildProcess_impl();
 
     bool m_lowPriority = false;
     bool m_unixTerminalDisabled = false;