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.