Not able to resolve std::atomic operations in Qt 5.15.2

Praveen.Illa

Hello Team,

I am trying to using C++ atomic variables in Qt 5.15.2. But I am getting an error "no template named 'atomic' in namespace std".
Please find below sample code

#include <atomic>
std::atomic<bool> ready (false);

Could anyone please help me why am not able to use atomic in my Qt

SGaist

Hi,

Which OS are you on ?
Did you change the C++ standard to use in your .pro file ?

Praveen.Illa

@SGaist
I am using Ubuntu-18.04.1

In .pro file, we tried with below configurations, but no luck
CONFIG += c++11
QMAKE_CXXFLAGS +=-std=c++0x

g++ version -
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.5.0-3ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)

SGaist

Can you build that file directly on the command line ?

Praveen.Illa

@SGaist
Yes, I am able to build successfully from command line in Ubuntu Terminal

SGaist

Can you provide a minimal main.cpp and .pro file that shows the issue ?

Praveen.Illa

@SGaist
My pro file looks like

QT += quick
CONFIG += c++11

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
        main.cpp

INCLUDEPATH += /usr/include/

DEFINES += LINUX

RESOURCES += qml.qrc

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =

# Additional import path used to resolve QML modules just for Qt Quick Designer
QML_DESIGNER_IMPORT_PATH =

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

main.cpp looks like

#include <QGuiApplication>
#include <QQmlApplicationEngine>

#include <iostream>
#include <atomic>
std::atomic<bool> ready (false);


int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

Not resolving <iostream> and <atomic> directives

kshegunov

@Praveen-Illa said in Not able to resolve std::atomic operations in Qt 5.15.2:

Not resolving <iostream> and <atomic> directives

Install the c++ development packages for your platform and compiler, possibly for the atomic library, drop the superfluous INCLUDEPATH+= from your project and link against the atomic library if necessary: LIBS += -latomic.