aitor_czr <aitor_czr@???> writes:
> Hi Rainer,
>
> I added cmake, which generates the makefile:
>
> https://gitlab.com/aitor_czr/spinner/commits/master
>
> How to build:
>
> mkdir build
> cd build
> cmake ../
> make

In case this wasn't plain enough: You shouldn't just use C++ because
some C++ user is convinced that writing anything in another programming
language must be a grievious error. They're all concinved of that and
for that matter, if you're only tool is a combined

lawnmower-hovercraft-main-battle-tank-guided-missile-destroyer-eggwarmer-toothpick-and-vibraphone

you're more likely to complain that parking spaces are all so much too
tight than consider how people ever manage to park the more specialized
vehicles totally fit for the purpose of 'human & groceries
transportation' in them.

Likewise, a complete, working Makefile for your project looks like this:

---------
.PHONY: clean

spinner: spinner.cpp
    g++ -o $@ $< `pkg-config --cflags --libs gtkmm-3.0`

clean:
    -rm spinner
--------

So, until things get much more complicated, why not just use make?