--- /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
+
+DESCRIPTION="C++ runtime stack unwinder from LLVM"
+HOMEPAGE="https://github.com/llvm-mirror/libunwind"
+LLVM_COMPONENTS=( libunwind )
+LLVM_TEST_COMPONENTS=( libcxx{,abi} )
+llvm.org_set_globals
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS=""
+IUSE="debug +static-libs test"
+RESTRICT="!test? ( test )"
+
+RDEPEND="!sys-libs/libunwind"
+# llvm-6 for new lit options
+DEPEND="
+ >=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[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+ use test && python-any-r1_pkg_setup
+}
+
+multilib_src_configure() {
+ local libdir=$(get_libdir)
+
+ local mycmakeargs=(
+ -DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+ -DLIBUNWIND_ENABLE_ASSERTIONS=$(usex debug)
+ -DLIBUNWIND_ENABLE_STATIC=$(usex static-libs)
+ -DLLVM_INCLUDE_TESTS=$(usex test)
+
+ # support non-native unwinding; given it's small enough,
+ # enable it unconditionally
+ -DLIBUNWIND_ENABLE_CROSS_UNWINDING=ON
+ )
+ 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}"
+ -DLIBUNWIND_LIBCXX_PATH="${WORKDIR}/libcxx"
+ )
+ fi
+
+ cmake-utils_src_configure
+}
+
+build_libcxxabi() {
+ local -x LDFLAGS="${LDFLAGS} -L${BUILD_DIR}/$(get_libdir)"
+ local CMAKE_USE_DIR=${WORKDIR}/libcxxabi
+ local BUILD_DIR=${BUILD_DIR}/libcxxabi
+ local mycmakeargs=(
+ -DLIBCXXABI_LIBDIR_SUFFIX=
+ -DLIBCXXABI_ENABLE_SHARED=OFF
+ -DLIBCXXABI_ENABLE_STATIC=ONF
+ -DLIBCXXABI_USE_LLVM_UNWINDER=ON
+ -DLIBCXXABI_INCLUDE_TESTS=OFF
+
+ -DLIBCXXABI_LIBCXX_INCLUDES="${WORKDIR}"/libcxx/include
+ -DLIBCXXABI_LIBUNWIND_INCLUDES="${S}"/include
+ )
+
+ cmake-utils_src_configure
+ cmake-utils_src_compile
+}
+
+build_libcxx() {
+ local -x LDFLAGS="${LDFLAGS} -L${BUILD_DIR}/libcxxabi/lib -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
+ -DLIBCXXABI_USE_LLVM_UNWINDER=ON
+ -DLIBCXX_CXX_ABI=libcxxabi
+ -DLIBCXX_CXX_ABI_INCLUDE_PATHS="${WORKDIR}"/libcxxabi/include
+ -DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+ -DLIBCXX_HAS_MUSL_LIBC=$(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 local copies of libc++ & libc++abi for testing to avoid
+ # circular deps
+ build_libcxxabi
+ build_libcxx
+ mv "${BUILD_DIR}"/libcxx*/lib/libc++* "${BUILD_DIR}/$(get_libdir)/" || die
+
+ local -x LIT_PRESERVES_TMP=1
+ cmake-utils_src_make check-unwind
+}
+
+multilib_src_install() {
+ cmake-utils_src_install
+
+ # install headers like sys-libs/libunwind
+ doheader "${S}"/include/*.h
+}