*/*: update for slotted Rust

guru version of this commit:
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=01ba4dc61965ef7658a24728841c04c9a1ce4871

Closes: https://bugs.gentoo.org/943170
Closes: https://bugs.gentoo.org/943223
Closes: #260
Signed-off-by: Takuya Wakazono <pastalian46@gmail.com>

sys-apps/bat-extras/bat-extras-9999.ebuild

@@ -1,8 +1,10 @@
-# Copyright 2022-2023 Gentoo Authors
+# Copyright 2022-2024 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
 
+inherit optfeature
+
 DESCRIPTION="Bash scripts that integrate bat with various command line tools."
 HOMEPAGE="https://github.com/eth-p/bat-extras"
 if [[ ${PV} == 9999 ]]; then
@@ -34,7 +36,6 @@ RDEPEND="
 	sys-apps/ripgrep
 	sys-devel/clang[extra(+)]
 	sys-libs/ncurses
-	virtual/rust[rustfmt(+)]
 "
 
 src_unpack() {
@@ -70,4 +71,6 @@ pkg_postinst() {
 	einfo "'net-libs/nodejs' is installed in your system, and use 'npm' to install"
 	einfo "'prettier' (npm i -g prettier). Once 'prettier' is properly installed in"
 	einfo "your system, remerge this package."
+
+	optfeature "Rust code formatting" dev-lang/rust[rustfmt] dev-lang/rust-bin[rustfmt]
 }