Adding pre-built .o file(s) to CMakeLists.txt

[Gennadiy Rishkin]

Hi

Does anyone know the correct way to add an object file to CMakELists.txt for coorect compilation. So, using step-4 as an example, if I had say, make_grid() precompiled into make_grid.o, how would I then include it for compilation using cmake.

thanks

Gennadiy

[Matthias Maier]

You just list the object file(s) together with the source files.


If you use the "autopilot" style CMakeLists.txt from the examples, just
list them together with the sources:

SET(TARGET_SRC
step-4.cc
make_grid.o
)


If you have a custom CMakeLists.txt [1],

ADD_EXECUTABLE(step-4
step-4.cc
make_grid.o
)

Also have a look at the object target explained in [2].

Best,
Matthias


[1] http://www.dealii.org/developer/index.html
[2] http://www.dealii.org/developer/users/cmakelists.html#cmakesimple.libs

[Gennadiy Rishkin]

Thanks Matthias. I'm using the "autopilot" style CMakeLists.txt from the examples. When I do:

SET(TARGET_SRC
  step-4.cc
  make_grid.o
)

I get the error:

CMakeFiles/main.dir/main.cc.o: In function `Step4<3>::run()':
main.cc:(.text._ZN7Step4ILi3EE3runEv[Step4<3>::run()]+0x80): undefined reference to `Step4<3>::make_grid()'

Thanks,

Gennadiy

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[Matthias Maier]

Am 08. Oct 2013, 16:30 schrieb Gennadiy Rishkin <gennadiy...@gmail.com>:

> Thanks Matthias. I'm using the "autopilot" style CMakeLists.txt from
> the examples. When I do:
>
> SET(TARGET_SRC
>   step-4.cc
>   make_grid.o
> )
>
> I get the error:
>
> CMakeFiles/main.dir/main.cc.o: In function `Step4<3>::run()':
> main.cc:(.text._ZN7Step4ILi3EE3runEv[Step4<3>::run()]+0x80):
> undefined reference to `Step4<3>::make_grid()'

Does make_grid have the same function signature in both files and do you
instantiate make_grid in make_grid.o?

And, why do you use such a setup in the first place?

Best,
Matthias

[Gennadiy Rishkin]

hi Matthias,

Yes, make_grid has the same function signature in both files.
I have the step4 class definition and the necessary headers in "step4.h", the other classes including 'main' in step4.cc.

make_grid.cc includes step4.h as a header and then I compile make_grid.cc to make_grid.o using "g++ -O3 -I/path_to_required_headers -c make_grid.cc".

Then I add make_grid.o to SET(TARGET_SRC step4.cc make_grid.o)

But it still doesn't work.

I'm trying this to understand how to link a prebuilt object file (for which I do not have the source file) from an external library to deal.II.

Thanks.

Gennadiy

[Matthias Maier]

For a templated function/class in C++ it is not sufficient to just declare
and define them, you have to instantiate them as well if they reside in
a different compilation unit. Have you done that?

An example:

foo.h:

/* Function declaration: */
template<int i> void foo();


foo.cc

/* Function definition: */
template<int i> void foo()
{
return;
}

/* Explicit instantiation: */
template void foo<1>();