ldp

#!/bin/bash

#  Made for Gentoo. lld can be emerged from sys-devel/lld, Clang's linker.
#  LLD is supported by GCC 9 as an alternative linker. When using -flto
#  or -flto=thin, Clang will automatically multithread based on CPUs detected.
#  Incompatible with Prefix and shells lacking GNU extensions.

if [[ "$(ld -v | awk '{print $2}')" == "ld" ]]; then
		export DEFLD="bfd"
	elif [[ "$(ld -v | awk '{print $2}')" == "gold" ]]; then
		export DEFLD="gold";
	else
		export DEFLD=$(readlink /usr/bin/ld | cut -nc 13-)
fi

linkcheck()
{
if [[ $(grep -v "\#\|USE" /etc/portage/make.conf | grep -o '\-\fuse\-\linker\-\plugin') == '-fuse-linker-plugin' ]]; then
		echo -e "\n-fuse-linker-plugin is being used in make.conf."
	elif test -n $(grep -v "\#\|USE" /etc/portage/make.conf | grep -o '\-\fuse\-\ld'); then
		echo -e "\nLinker in make.conf: $(grep -v "\#\|USE" /etc/portage/make.conf | grep -o  "\-\fuse\-\ld\=.*d" | cut -nc 10-)";
	else
		exit 1
fi
}


help()
{
echo "Options to change the default system linker.
Usage: ldp ${DEFLD} -- switches linker; bfd, gold, and lld are supported.
           ldp -- outputs the /usr/bin/ld symlink and linker in make.conf, if defined.

If -fuse-ld= is explicitly set in make.conf instead of
-fuse-linker-plugin, that will be replaced, too.

Note: Incompatible with Prefix and shells lacking GNU extensions."
}


for l in "${1}"
do

	case "${1}" in
	"-h" | "--help")
		help
		;;

	"bfd" | "gold" |  "lld")
		if [ -f /usr/bin/ld.${1} ] && [[ $UID == "0" ]]; then
				echo "Setting ${1} as the default linker." ;
				ln -sf  /usr/bin/ld.${l} /usr/bin/ld  ;
				sed -i  "/^{\-\\|C\|f}/s/bfd\|gold\|lld/${1}/" /etc/portage/make.conf;
			elif [[ $UID != "0" ]]; then
				echo "Changing the linker requires root permissions. No changes were made.";
			else
				echo "${1} was not found in the standard directory. No changes were made."
			exit 1
		fi
		;;

	*)
		echo -e "Symlink /usr/bin/ld: ${DEFLD}\c";
		linkcheck
	esac
done