undefined reference to _imp_

dansab

Dear Forum,

I know that there are forum posts with similar topics but I did not found a solution so far.

I have an external .lib to include to my project. I am using MinGW 64bit and Qt 5.15.0
I used the function "Add Library", selected external and selected the .lib.

unix:!macx|win32: LIBS += -L$$PWD/./ -llibe9u_LSMD_x64

INCLUDEPATH += $$PWD/.
DEPENDPATH += $$PWD/.

Now I get multiple "undefinde reference to imp" errors. The supplier of the lib says that it was created using a cross compiler.

I found this:
https://stackoverflow.com/questions/30767553/undefined-reference-when-using-c11-qmake-flags

And added:

QMAKE_CXXFLAGS += -std=c++11
CONFIG += c++11

But that did not help.

The lib works with Visual Studio. I also tried Qt VS Tools, but that also generated LNK2019 errors.

Any help appreciated.

Thanks!
Dan

JonB

@dansab
Are these .lib files giving "imp..." warnings from MSVC and you are trying to link them with MinGW?

dansab

Hi JonB,

the problem was, that some .h were written in C, so this problem was solved by

extern "C"
{
#include...
}

This error message is incredible unspecific...
Shouldn't a C or C++ compiler be able to recognize this?

cheers,
Dan

Christian Ehrlicher

@dansab said in undefined reference to _imp_:

Shouldn't a C or C++ compiler be able to recognize this?

How? You told the compiler that you're using a c++ function, but the library only exported the c name - how should a linker (not compiler btw) know about this - these are two different symbols for them.