You receive this bug because this package does not respect my system's CC ( x86_64-pc-linux-gnu-gcc - /usr/bin/x86_64-pc-linux-gnu-gcc ) and calls directly gcc -/usr/bin/gcc The possible solutions to fix this issue are: 1)Fix the buildsystem, if you can 2)inherit toolchain-funcs and use tc-export CC 3)inherit toolchain-funcs and use emake CC="$(tc-getCC)" This package partially does not respect CC: g-ir-scanner: compile: gcc -Wall -pthread -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -march=native -g0 -O2 -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -c -o /tmp/portage/x11-misc/lightdm-1.4.0/work/lightdm-1.4.0/liblightdm-gobject/tmp-introspectFe8H9C/LightDM-1.o /tmp/portage/x11-misc/lightdm-1.4.0/work/lightdm-1.4.0/liblightdm-gobject/tmp-introspectFe8H9C/LightDM-1.c libtool: link: gcc -o /tmp/portage/x11-misc/lightdm-1.4.0/work/lightdm-1.4.0/liblightdm-gobject/tmp-introspectFe8H9C/.libs/LightDM-1 -march=native -g0 -O2 /tmp/portage/x11-misc/lightdm-1.4.0/work/lightdm-1.4.0/liblightdm-gobject/tmp-introspectFe8H9C/LightDM-1.o -pthread -Wl,--export-dynamic -Wl,--export-dynamic -L. ./.libs/liblightdm-gobject-1.so -lxklavier -lX11 -lgio-2.0 -lgobject-2.0 -lgthread-2.0 -lgmodule-2.0 -lrt -lglib-2.0 -pthread and at configure time: checking whether gcc understands -Wno-sign-compare... yes
@Markos, lightdm-gtk-greeter has the same problem at configure time
*** This bug has been marked as a duplicate of bug 463846 ***