--- /dev/null
+# Copyright 1999-2020 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+PYTHON_COMPAT=( python3_{6,7} )
+inherit cmake-multilib llvm llvm.org multiprocessing python-any-r1 toolchain-funcs
+
+DESCRIPTION="Low level support for a standard C++ library"
+HOMEPAGE="https://libcxxabi.llvm.org/"
+# libcxx is needed uncondtionally for the headers
+LLVM_COMPONENTS=( libcxx{abi,} )
+llvm.org_set_globals
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS=""
+IUSE="+libunwind +static-libs test elibc_musl"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+ libunwind? (
+ || (
+ >=sys-libs/libunwind-1.0.1-r1[static-libs?,${MULTILIB_USEDEP}]
+ >=sys-libs/llvm-libunwind-3.9.0-r1[static-libs?,${MULTILIB_USEDEP}]
+ )
+ )"
+# llvm-6 for new lit options
+DEPEND="${RDEPEND}
+ >=sys-devel/llvm-6"
+BDEPEND="
+ test? ( >=sys-devel/clang-3.9.0
+ $(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]') )"
+
+# least intrusive of all
+CMAKE_BUILD_TYPE=RelWithDebInfo
+
+python_check_deps() {
+ has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+ llvm_pkg_setup
+ use test && python-any-r1_pkg_setup
+}
+
+multilib_src_configure() {
+ # link against compiler-rt instead of libgcc if we are using clang with libunwind
+ local want_compiler_rt=OFF
+ if use libunwind && tc-is-clang; then
+ local compiler_rt=$($(tc-getCC) ${CFLAGS} ${CPPFLAGS} \
+ ${LDFLAGS} -print-libgcc-file-name)
+ if [[ ${compiler_rt} == *libclang_rt* ]]; then
+ want_compiler_rt=ON
+ fi
+ fi
+
+ local libdir=$(get_libdir)
+ local mycmakeargs=(
+ -DLIBCXXABI_LIBDIR_SUFFIX=${libdir#lib}
+ -DLIBCXXABI_ENABLE_SHARED=ON
+ -DLIBCXXABI_ENABLE_STATIC=$(usex static-libs)
+ -DLIBCXXABI_USE_LLVM_UNWINDER=$(usex libunwind)
+ -DLIBCXXABI_INCLUDE_TESTS=$(usex test)
+ -DLIBCXXABI_USE_COMPILER_RT=${want_compiler_rt}
+
+ -DLIBCXXABI_LIBCXX_INCLUDES="${WORKDIR}"/libcxx/include
+ # upstream is omitting standard search path for this
+ # probably because gcc & clang are bundling their own unwind.h
+ -DLIBCXXABI_LIBUNWIND_INCLUDES="${EPREFIX}"/usr/include
+ )
+ if use test; then
+ local clang_path=$(type -P "${CHOST:+${CHOST}-}clang" 2>/dev/null)
+ local jobs=${LIT_JOBS:-$(makeopts_jobs "${MAKEOPTS}" "$(get_nproc)")}
+
+ [[ -n ${clang_path} ]] || die "Unable to find ${CHOST}-clang for tests"
+
+ mycmakeargs+=(
+ -DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+ -DLLVM_LIT_ARGS="-vv;-j;${jobs};--param=cxx_under_test=${clang_path}"
+ )
+ fi
+ cmake-utils_src_configure
+}
+
+build_libcxx() {
+ local -x LDFLAGS="${LDFLAGS} -L${BUILD_DIR}/$(get_libdir)"
+ local CMAKE_USE_DIR=${WORKDIR}/libcxx
+ local BUILD_DIR=${BUILD_DIR}/libcxx
+ local mycmakeargs=(
+ -DLIBCXX_LIBDIR_SUFFIX=
+ -DLIBCXX_ENABLE_SHARED=OFF
+ -DLIBCXX_ENABLE_STATIC=ON
+ -DLIBCXX_ENABLE_EXPERIMENTAL_LIBRARY=OFF
+ -DLIBCXX_CXX_ABI=libcxxabi
+ -DLIBCXX_CXX_ABI_INCLUDE_PATHS="${S}"/include
+ -DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+ -DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+ -DLIBCXX_HAS_GCC_S_LIB=OFF
+ -DLIBCXX_INCLUDE_TESTS=OFF
+ )
+
+ cmake-utils_src_configure
+ cmake-utils_src_compile
+}
+
+multilib_src_test() {
+ # build a local copy of libc++ for testing to avoid circular dep
+ build_libcxx
+ mv "${BUILD_DIR}"/libcxx/lib/libc++* "${BUILD_DIR}/$(get_libdir)/" || die
+
+ local -x LIT_PRESERVES_TMP=1
+ cmake-utils_src_make check-libcxxabi
+}
+
+multilib_src_install_all() {
+ insinto /usr/include/libcxxabi
+ doins -r include/.
+}