GRPC helloworld server "undefined references"

[NikoBir]

Hello everyone !

I want to design a gRPC server on Qt. So, I took the helloword program on grpc website and I linked it with Qt.
But this code exeample didn't work :

I use :

Os : Debian 9
Qt : 5.13.2
Protoc : 3.19.4

My pro file :

QT -= gui
#QT += protobuf grpc core

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

# The following define makes your compiler emit warnings if you use
# any Qt feature that has 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 it uses 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

INCLUDEPATH += \
    /home/name/.local/include/ \
    /home/name/.local/lib/ \

LIBS += -L/usr/local/lib `pkg-config --libs protobuf grpc++`
        -pthread
        -lgrpc++_reflection
        -ldl

SOURCES += \
    greeter_server.cc \
    helloworld.grpc.pb.cc \
    helloworld.pb.cc

HEADERS += \
    helloworld.grpc.pb.h \
    helloworld.pb.h

DISTFILES += \
    helloworld.proto

I have no idea how to solve this issue.
I really thank you in advance for your help !

[JonB]

@NikoBir said in GRPC helloworld server "undefined references":

pkg-config --libs protobuf grpc++

The output shows missing external references to grpc functions. Have you checked just what the pkg-config command above returns for use into the LIBS variable? Is that syntactically correct, and is it enough together with -lgrpc++_reflection everything needed? Have a look at the complete g++ link line as it is generated and issued fro Creator.

[SGaist]

Hi,

Your LIBS looks wrong on several levels. It's missing backslashes since you made it multiline and I do not remember that syntax for retrieving something.

qmake has support for pkg-config so you should rather use that.

[NikoBir]

Thanks both of you for your indication !
Indeed, it was the pkg-config (that didn't return the grpc.pc file) and my libs in LIBS.
So, I deleted the useless libs and I add in the PKG_CONFIG_PATH, the path to the grpc.pc lib.

Now, my pro file is :

QT -= gui
#QT += protobuf grpc core

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

# The following define makes your compiler emit warnings if you use
# any Qt feature that has 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 it uses 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

INCLUDEPATH += \
    /home/name/.local/include/ \
    /home/name/.local/lib/ \

LIBS += -L/usr/local/lib `pkg-config --libs grpc++`

SOURCES += \
    greeter_server.cc \
    helloworld.grpc.pb.cc \
    helloworld.pb.cc

HEADERS += \
    helloworld.grpc.pb.h \
    helloworld.pb.h

DISTFILES += \
    helloworld.proto

After correcting this issue, I have this error on the output terminal :

error while loading shared libraries: libgrpc++.so.1.45: cannot open shared object file: No such file or directory

So, after some research, I followed this advice :

https://forum.qt.io/topic/58963/error-while-loading-shared-libraries-cannot-open-shared-object-file-no-such-file-or-directory/3

but it was ineffective....

I tested to add in the pro file :

QMAKE_LFLAGS += -Wl,-rpath,"path_to_ibgrpc++.so.1.45"

Do you know how to resolve this issue ?

[SGaist]

Where is that library located in your machine ?

As an alternative, you can set the LD_LIBRARY_PATH environment variable and add that folder to it.

[NikoBir]

@SGaist said in GRPC helloworld server "undefined references":

LD_LIBRARY_PATH

Thanks for your answer !

The library is located in "/home/name/.local/lib/libgrpc++.so.1.45".
I tested your advice, I addes the directory path in my bashrc :
export LD_LIBRARY_PATH="/home/edf/.local/lib/"

And I updated it.

But, I have the same issue :/

[SGaist]

Are you sure your project picked it up ?
Check the Run part of the project panel.

[NikoBir]

Nevermind ! It worked !!!!!!! Thank you !!!