How to add -pthread compiler option in Qt?

[BadPistol97]

OS: Windows 7
Compiler: Qt 5.11.2 MinGW 32-bit
Program compiled in debug.

I am using Botan library recently to create a ECDSA_PrivateKey object. But the compiler is complaining about the undefined reference to 'std::thread::_State::~_State()' in rsa.cpp and thread_pool.cpp, both from botan.

This is how I added the botan library:

Code:

#include <QCoreApplication>
#include <botan/pubkey.h>
#include <botan/ec_group.h>
#include <botan/ecdsa.h>
#include <iostream>
#include <botan/pkcs8.h>
#include <string.h>

using std::cout;
using std::endl;


int main(int argc, char *argv[])
{

    QCoreApplication a(argc, argv);

    std::unique_ptr<Botan::RandomNumberGenerator> random(new Botan::System_RNG);

    std::unique_ptr<Botan::EC_Group> group(new Botan::EC_Group("secp256r1"));

    std::unique_ptr<Botan::ECDSA_PrivateKey> aKey(new Botan::ECDSA_PrivateKey(*random,*group));

    std::string encoded;

    // this line caused the error.
    encoded = Botan::PKCS8::PEM_encode(*aKey);

    return a.exec();
}

According to randombit: "Botan uses threads internally, you may have to add -pthread to gcc command line."

Now I know -pthread is a compiler option but when I try to use the option in cmd like: qmake -pthread, it says ***unknown option -pthread

Is -pthread really an option in Qt? And CONFIG += thread in .pro doesn't work. Need some help here, thanks in advance.

[SGaist]

Hi,

Add LIBS += -lpthread to your .pro file.

[Edit aha_1980: Fix typo]

[BadPistol97]

It doesn't work, the compiler is still complaining the same undefined reference.

.pro file:

QT -= gui

CONFIG += c++11 console
CONFIG -= app_bundle


# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
        main.cpp

QMAKE_LFLAGS +=-fstack-protector

LIBS +=-lpthread



# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

unix|win32: LIBS += -L$$PWD/../../../Enzo/Library/botan-master/botan-master/ -lbotan-2

INCLUDEPATH += $$PWD/../../../Enzo/Library/botan-master/botan-master/build/include
DEPENDPATH += $$PWD/../../../Enzo/Library/botan-master/botan-master/build/include

win32:!win32-g++: PRE_TARGETDEPS += $$PWD/../../../Enzo/Library/botan-master/botan-master/botan-2.lib
else:unix|win32-g++: PRE_TARGETDEPS += $$PWD/../../../Enzo/Library/botan-master/botan-master/libbotan-2.a

[BadPistol97]

I built the Botan library using my own MinGW 8.1.0 instead of Qt's MinGW, does that matter?

[aha_1980]

@BadPistol97 said in How to add -pthread compiler option in Qt?:

I built the Botan library using my own MinGW 8.1.0 instead of Qt's MinGW, does that matter?

Why don't you just try building it with the same version?

According to randombit: "Botan uses threads internally, you may have to add -pthread to gcc command line."

I think you can add this by QMAKE_CXXFLAGS += -pthread (QMAKE_CLFLAGS for C files resp.) to your .pro file.

However, I think you're just not linking to the correct library. Find out which one is exporting exactly the symbols you're missing.

At least, this line: LIBS +=-lpthread just links against libpthread.so. Where do you link against botan?

Regards

[BadPistol97]

@aha_1980 I have rebuilt the botan library using Qt's own MinGW compiler and now it works.

But the botan-test stuck when testing tls:

[aha_1980]

@BadPistol97 I'd say run it in a debugger, and when it crashes send the stack trace to the botan developers.

They might be best telling you what goes wrong and if it is harmful.

Regards

[BadPistol97]

Thank you very much.