Error occurs while building QtMqtt module

franc

Hi all, I am trying to build QtMqtt module on Windows 10 (using VS Dev14 command line developer tool).

Following the indications found on Google, I have cloned http://code.qt.io/cgit/qt/qtmqtt.git/ in C:\Qt\5.11.1\Src, and I performed the following commands:

mkdir build
pushd build
qmake -r ..
nmake

Everything goes fine (or I hope so) until qmake -r .., and with nmake the compilation of qmqttclient.cpp, qmqttconnection.cpp, qmqttcontrolpacket.cpp, qmqttmessage.cpp and qmqttsubscription.cpp goes fine too.

When it's the turn of qmqtttopicfilter.cpp I get two errors, which do not allow me to proceed further:

C:\Qt\5.11.1\Src\qtmqtt\src\mqtt\qmqtttopicfilter.cpp(207): error C2678: binary '==': no operator found which takes a left-hand operand of type 'QString' (or there is no acceptable conversion)

C:\Qt\5.11.1\Src\qtmqtt\src\mqtt\qmqtttopicfilter.cpp(225): error C2678: binary '!=': no operator found which takes a left-hand operand of type 'const QStringRef' (or there is no acceptable conversion)

Please, take into account that I have three different versions of Qt installed (5.7, 5.11.1 and 5.11.2), and I have not excluded incompatibility issues, even though I did not find any.

Edit:
changing the lines

(206)      || d->filter == QLatin1Char('#')
(207)      || d->filter == QLatin1String("/#"))) {

with

(206)      || d->filter == QString('#')
(207)      || d->filter == QString("/#"))) {

and the line

(225)      if (level != QLatin1Char('+') && level != topicLevels.at(i))

with

(225)      if (level != QString('+') && level != topicLevels.at(i))

solves the problem. I do not have tested it yet, anyway.

SGaist

Hi,

What exact version of the compiler are you using ?
What branch are you trying to build ?

On a side note, you should rathe use out of source builds.

franc

@SGaist

Hi, I am building branch 5.11, and the compiler is exactly the following:

Microsoft (R) C/C++ Optimizing Compiler Version 19.00.24215.1 for x64

Two further things:

The same errors as above are marked even on Qt Creator.
I have run the example MQTT Subscriptions Example with the above modifications, and everything goes fine.

SGaist

I'd suspect an issue with your compiler: QString::operator==(QLatin1String other) has been there for a long time.