Created attachment 870978 [details] ls /etc/portage/env/ for me it seems like the problem with ts-is-clang at https://gitweb.gentoo.org/repo/gentoo.git/tree/net-misc/networkmanager/networkmanager-1.42.6-r1.ebuild#n155
Created attachment 870979 [details] compiler-gcc-lto.conf
Created attachment 870980 [details] package.env
Created attachment 870981 [details] emerge --info -v networkmanager , but it's useless because https://wiki.gentoo.org/wiki//etc/portage/package.env#emerge_--info_does_not_show_changes_from_package.env
Created attachment 870982 [details] /var/tmp/portage/net-misc/networkmanager-1.42.6-r1/temp/build.log
I can confirm, that cdrtools compiles using gcc-lto config, even though emerge --info cdrtools tells that CC="clang" . So, it's not the problem with compiler-gcc-lto.conf . I don't think it's a problem with package.env.
Created attachment 870983 [details] /var/tmp/portage/net-misc/networkmanager-1.42.6-r1/temp/die.env
solved by adding CPP="${CXX}" at compile-gcc-lto.conf . Thanks @sam_ !
should be CPP="cpp" .