Qt Creator prompts the static library to have an unresolved external symbol but it's work well in VS

wzj1695224

I has an project, like that:

QZXing
  |----LibZXing     (Static Library)
  |----Demo         (Console Application)

The LibZXing was built with none error and link success with same code in VS. When I try to build Demo, I got some unresolved externam symbol of LibZXing.

LibZXing.pro

QT -= core gui

TEMPLATE = lib
CONFIG += staticlib

TARGET = libzxing

DESTDIR = ../lib

SOURCES += LibZXing.cpp \
    src/zxing/BarcodeFormat.cpp \
    ...

HEADERS += LibZXing.h \
    src/zxing/BarcodeFormat.h \
    ...

Demo.pro:

QT -= core gui

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

TARGET = Demo
TEMPLATE = app

INCLUDEPATH += $$PWD/../LibZXing/src
LIBS += -L../lib/ -llibzxing

SOURCES += main.cpp

ibzxing.lib(QRCodeReader.obj):-1: error: LNK2019: unresolved external symbol "public: __cdecl zxing::qrcode::Decoder::Decoder(void)" (??0Decoder@qrcode@zxing@@QEAA@XZ) referenced in function "public: __cdecl zxing::qrcode::QRCodeReader::QRCodeReader(void)" (??0QRCodeReader@qrcode@zxing@@QEAA@XZ)
...
libzxing.lib(DataMatrixReader.obj):-1: error: LNK2019: unresolved external symbol "public: __cdecl zxing::datamatrix::Decoder::Decoder(void)" (??0Decoder@datamatrix@zxing@@QEAA@XZ) referenced in function "public: __cdecl zxing::datamatrix::DataMatrixReader::DataMatrixReader(void)" (??0DataMatrixReader@datamatrix@zxing@@QEAA@XZ)
...
libzxing.lib(PDF417Reader.obj):-1: error: LNK2019: unresolved external symbol "public: class zxing::Ref<class zxing::DecoderResult> __cdecl zxing::pdf417::decoder::Decoder::decode(class zxing::Ref<class zxing::BitMatrix>,class zxing::DecodeHints const &)" (?decode@Decoder@decoder@pdf417@zxing@@QEAA?AV?$Ref@VDecoderResult@zxing@@@4@V?$Ref@VBitMatrix@zxing@@@4@AEBVDecodeHints@4@@Z) referenced in function "public: virtual class zxing::Ref<class zxing::Result> __cdecl zxing::pdf417::PDF417Reader::decode(class zxing::Ref<class zxing::BinaryBitmap>,class zxing::DecodeHints)" (?decode@PDF417Reader@pdf417@zxing@@UEAA?AV?$Ref@VResult@zxing@@@3@V?$Ref@VBinaryBitmap@zxing@@@3@VDecodeHints@3@@Z)
...
qtmaind.lib(qtmain_win.obj):-1: error: LNK2019: unresolved external symbol main referenced in function WinMain

Here is my project: Dropbox Share
Thanks for your helping.

jsulm

@wzj1695224 Remove lib from LIBS += -L../lib/ -llibzxing

LIBS += -L../lib/ -lzxing

wzj1695224

@jsulm

 error: LNK1104: cannot open file 'zxing.lib'

SGaist

Hi,

Where is libzxing.lib exactly located on your hard drive ?

wzj1695224

@SGaist

E:\Developments\Source\.build-qt-QZXing-Qt_5_7_0_MSVC_14_0\lib

I had try to using absolute path, but it still have those problems.

E:\Developments\Source
    |------.build-qt-QZXing-Qt_5_7_0_MSVC_14_0
    |          |-----------Demo (folder)
    |          |-----------lib (folder)
    |          |                |-------libzxing.lib
    |          |-----------LibZXing (folder)
    |
    |------QZXing
    |          |--------QZXing.pro
    |          |--------Demo (folder)
    |          |            |---------Demo.pro
    |          |           ...
    |          |--------LibZXing (folder)
    |          |            |---------LibZXing.pro
    |          |           ...

SGaist

Are you sure you are linking against a static version of libzxing.lib ?
Because otherwise, it looks like the symbol are not properly tagged for export/import.

wzj1695224

@SGaist
Merry Christmas!
Yes, the libzxing.lib Qt Creator builds is same size as VS builds
I has share my project.
https://www.dropbox.com/s/d9o5zyirazbruty/QZXing.zip?dl=0

SGaist

Your main.cpp file is faulty, it doesn't contain a main function but a mains function.

wzj1695224

@SGaist
Cause I want to test some function, so I wrote a new main function and renamed old one to mains. I forgot to change it back.
But this is not the key to my question, is it?
p.s. I had update the QZXing.zip

SGaist

No indeed, it's not the key. However, having to first debug a project before being able to trigger the bug to check what is going wrong is not really nice.