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

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>bsd</herd>
  <!-- BSD is here because the plan is to have libc++ as the standard C++
	   library with clang. A llvm herd would make a lot of sense here too -->
  <maintainer>
    <email>aballier@gentoo.org</email>
    <name>Alexis Ballier</name>
  </maintainer>
  <use>
	  <flag name="libcxxrt">Build on top of <pkg>sys-libs/libcxxrt</pkg> instead of gcc's libsupc++ (avoids depending on gcc).</flag>
  </use>
</pkgmetadata>