--- /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="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+LLVM_COMPONENTS=( libcxx )
+llvm.org_set_globals
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS=""
+IUSE="elibc_glibc elibc_musl +libcxxabi +libunwind +static-libs test"
+REQUIRED_USE="libunwind? ( libcxxabi )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+ libcxxabi? ( ~sys-libs/libcxxabi-${PV}[libunwind=,static-libs?,${MULTILIB_USEDEP}] )
+ !libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )"
+# llvm-6 for new lit options
+# clang-3.9.0 installs necessary target symlinks unconditionally
+# which removes the need for MULTILIB_USEDEP
+DEPEND="${RDEPEND}
+ >=sys-devel/llvm-6"
+BDEPEND="
+ test? ( >=sys-devel/clang-3.9.0
+ $(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]') )"
+
+DOCS=( CREDITS.TXT )
+
+PATCHES=(
+ # Add link flag "-Wl,-z,defs" to avoid underlinking; this is needed in a
+ # out-of-tree build.
+ "${FILESDIR}/${PN}-3.9-cmake-link-flags.patch"
+)
+
+# 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
+
+ if ! use libcxxabi && ! tc-is-gcc ; then
+ eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+ eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+ eerror "and try again."
+ die
+ fi
+}
+
+test_compiler() {
+ $(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+ <<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+ # note: we need to do this before multilib kicks in since it will
+ # alter the CHOST
+ local cxxabi cxxabi_incs
+ if use libcxxabi; then
+ cxxabi=libcxxabi
+ cxxabi_incs="${EPREFIX}/usr/include/libcxxabi"
+ else
+ local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+ cxxabi=libsupc++
+ cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+ fi
+
+ multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+ # we want -lgcc_s for unwinder, and for compiler runtime when using
+ # gcc, clang with gcc runtime (or any unknown compiler)
+ local extra_libs=() want_gcc_s=ON want_compiler_rt=OFF
+ if use libunwind; then
+ # work-around missing -lunwind upstream
+ extra_libs+=( -lunwind )
+ # if we're using libunwind and clang with compiler-rt, we want
+ # to link to compiler-rt instead of -lgcc_s
+ if tc-is-clang; then
+ local compiler_rt=$($(tc-getCC) ${CFLAGS} ${CPPFLAGS} \
+ ${LDFLAGS} -print-libgcc-file-name)
+ if [[ ${compiler_rt} == *libclang_rt* ]]; then
+ want_gcc_s=OFF
+ want_compiler_rt=ON
+ extra_libs+=( "${compiler_rt}" )
+ fi
+ fi
+ fi
+
+ # bootstrap: cmake is unhappy if compiler can't link to stdlib
+ local nolib_flags=( -nodefaultlibs -lc )
+ if ! test_compiler; then
+ if test_compiler "${nolib_flags[@]}"; then
+ local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+ ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+ fi
+ fi
+
+ local libdir=$(get_libdir)
+ local mycmakeargs=(
+ -DLIBCXX_LIBDIR_SUFFIX=${libdir#lib}
+ -DLIBCXX_ENABLE_SHARED=ON
+ -DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+ -DLIBCXX_CXX_ABI=${cxxabi}
+ -DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+ # we're using our own mechanism for generating linker scripts
+ -DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+ -DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+ -DLIBCXX_HAS_GCC_S_LIB=${want_gcc_s}
+ -DLIBCXX_INCLUDE_TESTS=$(usex test)
+ -DLIBCXX_USE_COMPILER_RT=${want_compiler_rt}
+ -DCMAKE_SHARED_LINKER_FLAGS="${extra_libs[*]} ${LDFLAGS}"
+ )
+
+ if use test; then
+ local clang_path=$(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
+}
+
+multilib_src_test() {
+ local -x LIT_PRESERVES_TMP=1
+ cmake-utils_src_make check-libcxx
+}
+
+# Usage: deps
+gen_ldscript() {
+ local output_format
+ output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+ [[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+ cat <<-END_LDSCRIPT
+/* GNU ld script
+ Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+ local libdir=$(get_libdir)
+ local cxxabi_lib=$(usex libcxxabi "libc++abi.a" "libsupc++.a")
+
+ # Move it first.
+ mv "${ED}/usr/${libdir}/libc++.a" "${ED}/usr/${libdir}/libc++_static.a" || die
+ # Generate libc++.a ldscript for inclusion of its dependencies so that
+ # clang++ -stdlib=libc++ -static works out of the box.
+ local deps="libc++_static.a ${cxxabi_lib} $(usex libunwind libunwind.a libgcc_eh.a)"
+ # On Linux/glibc it does not link without libpthread or libdl. It is
+ # fine on FreeBSD.
+ use elibc_glibc && deps+=" libpthread.a libdl.a"
+
+ gen_ldscript "${deps}" > "${ED}/usr/${libdir}/libc++.a" || die
+}
+
+gen_shared_ldscript() {
+ local libdir=$(get_libdir)
+ # libsupc++ doesn't have a shared version
+ local cxxabi_lib=$(usex libcxxabi "libc++abi.so" "libsupc++.a")
+
+ mv "${ED}/usr/${libdir}/libc++.so" "${ED}/usr/${libdir}/libc++_shared.so" || die
+ local deps="libc++_shared.so ${cxxabi_lib} $(usex libunwind libunwind.so libgcc_s.so)"
+
+ gen_ldscript "${deps}" > "${ED}/usr/${libdir}/libc++.so" || die
+}
+
+multilib_src_install() {
+ cmake-utils_src_install
+ gen_shared_ldscript
+ use static-libs && gen_static_ldscript
+}
+
+pkg_postinst() {
+ elog "This package (${PN}) is mainly intended as a replacement for the C++"
+ elog "standard library when using clang."
+ elog "To use it, instead of libstdc++, use:"
+ elog " clang++ -stdlib=libc++"
+ elog "to compile your C++ programs."
+}