$ LC_ALL=C makepkg -csi
[...]
Making all in src
make[2]: Entering directory `/home/dennis/Hämtningar/AUR/cinnamon/src/linuxmint-Cinnamon-e84a25b/src'
  GEN      st-enum-types.c
  GEN      stamp-st-marshal.h
  GEN      st-marshal.c
  GEN      stamp-st.h
  GEN      stamp-na-marshal.h
  GEN      na-marshal.c
  GEN      stamp-cinnamon-marshal.h
  GEN      cinnamon-marshal.c
  GEN      cinnamon-enum-types.c
make  all-am
make[3]: Entering directory `/home/dennis/Hämtningar/AUR/cinnamon/src/linuxmint-Cinnamon-e84a25b/src'
  CC       libst_1_0_la-st-bin.lo
st/st-bin.c: In function 'st_bin_set_child':
st/st-bin.c:465:7: error: 'clutter_actor_unparent' is deprecated (declared at /usr/include/clutter-1.0/clutter/deprecated/clutter-actor.h:58): Use 'clutter_actor_remove_child' instead [-Werror=deprecated-declarations]
st/st-bin.c:475:7: error: 'clutter_actor_set_parent' is deprecated (declared at /usr/include/clutter-1.0/clutter/deprecated/clutter-actor.h:54): Use 'clutter_actor_add_child' instead [-Werror=deprecated-declarations]
cc1: all warnings being treated as errors
make[3]: *** [libst_1_0_la-st-bin.lo] Error 1
make[3]: Leaving directory `/home/dennis/Hämtningar/AUR/cinnamon/src/linuxmint-Cinnamon-e84a25b/src'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/home/dennis/Hämtningar/AUR/cinnamon/src/linuxmint-Cinnamon-e84a25b/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/dennis/Hämtningar/AUR/cinnamon/src/linuxmint-Cinnamon-e84a25b'
make: *** [all] Error 2
==> ERROR: A failure occurred in build().
    Aborting...