Ensure that readAllStandardError() doesn't crash on assert

Ensure that it's safe to call readAllStandardError()
when process channel mode is set to MergedChannels.

Pick-to: 6.3 6.3.0
Task-number: QTBUG-102177
Task-number: QTCREATORBUG-27196
Change-Id: I01073255d9347dee4654d602802a12d341372b73
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index f58783d510..67385e2698 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -1942,10 +1942,16 @@ QByteArray QProcess::readAllStandardOutput()
 */
 QByteArray QProcess::readAllStandardError()
 {
-    ProcessChannel tmp = readChannel();
-    setReadChannel(StandardError);
-    QByteArray data = readAll();
-    setReadChannel(tmp);
+    Q_D(QProcess);
+    QByteArray data;
+    if (d->processChannelMode == MergedChannels) {
+        qWarning("QProcess::readAllStandardError: Called with MergedChannels");
+    } else {
+        ProcessChannel tmp = readChannel();
+        setReadChannel(StandardError);
+        data = readAll();
+        setReadChannel(tmp);
+    }
     return data;
 }