gentoo-overlay/sys-libs/libcxxabi/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<maintainer type="project">
		<email>llvm@gentoo.org</email>
	</maintainer>
	<use>
		<flag name="libunwind">Use libunwind instead of libgcc_s for stack unwinding, thus avoiding dependency on gcc</flag>
	</use>
</pkgmetadata>