# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

EAPI=7

PYTHON_COMPAT=( python3_{6,7,8} )

inherit bash-completion-r1 check-reqs estack flag-o-matic llvm multiprocessing multilib-build python-any-r1 rust-toolchain toolchain-funcs

if [[ ${PV} = *beta* ]]; then
	betaver=${PV//*beta}
	BETA_SNAPSHOT="${betaver:0:4}-${betaver:4:2}-${betaver:6:2}"
	MY_P="rustc-beta"
	SLOT="beta/${PV}"
	SRC="${BETA_SNAPSHOT}/rustc-beta-src.tar.xz"
else
	ABI_VER="1.46"
	SLOT="stable/${ABI_VER}"
	MY_P="rustc-${PV}"
	SRC="${MY_P}-src.tar.xz"
	KEYWORDS="~amd64"
fi

RUST_STAGE0_VERSION="1.$(($(ver_cut 2) - 1)).1"

DESCRIPTION="Systems programming language from Mozilla"
HOMEPAGE="https://www.rust-lang.org/"

SRC_URI="
	https://static.rust-lang.org/dist/${SRC} -> rustc-${PV}-src.tar.xz
	!system-bootstrap? ( $(rust_arch_uri x86_64-unknown-linux-gnu rust-${RUST_STAGE0_VERSION}) )
"

ALL_LLVM_TARGETS=( AArch64 AMDGPU ARM BPF Hexagon Lanai Mips MSP430
	NVPTX PowerPC RISCV Sparc SystemZ WebAssembly X86 XCore )
ALL_LLVM_TARGETS=( "${ALL_LLVM_TARGETS[@]/#/llvm_targets_}" )
LLVM_TARGET_USEDEPS=${ALL_LLVM_TARGETS[@]/%/?}

LICENSE="|| ( MIT Apache-2.0 ) BSD-1 BSD-2 BSD-4 UoI-NCSA"

IUSE="clippy cpu_flags_x86_sse2 debug doc libressl miri nightly parallel-compiler rls rustfmt system-bootstrap system-llvm wasm ${ALL_LLVM_TARGETS[*]}"

# Please keep the LLVM dependency block separate. Since LLVM is slotted,
# we need to *really* make sure we're not pulling more than one slot
# simultaneously.

# How to use it:
# 1. List all the working slots (with min versions) in ||, newest first.
# 2. Update the := to specify *max* version, e.g. < 11.
# 3. Specify LLVM_MAX_SLOT, e.g. 10.
LLVM_DEPEND="
	|| (
		sys-devel/llvm:10[${LLVM_TARGET_USEDEPS// /,}]
		sys-devel/llvm:9[${LLVM_TARGET_USEDEPS// /,}]
	)
	<sys-devel/llvm-11:=
	wasm? ( sys-devel/lld )
"
LLVM_MAX_SLOT=10

BOOTSTRAP_DEPEND="|| ( >=dev-lang/rust-1.$(($(ver_cut 2) - 1)) >=dev-lang/rust-bin-1.$(($(ver_cut 2) - 1)) )"

BDEPEND="${PYTHON_DEPS}
	|| (
		>=sys-devel/gcc-4.7
		>=sys-devel/clang-3.5
	)
	system-bootstrap? ( ${BOOTSTRAP_DEPEND} )
	!system-llvm? (
		dev-util/cmake
		dev-util/ninja
	)
"

# libgit2 should be at least same as bundled into libgit-sys #707746
DEPEND="
	>=dev-libs/libgit2-0.99:=
	net-libs/libssh2:=
	net-libs/http-parser:=
	net-misc/curl:=[http2,ssl]
	sys-libs/zlib:=
	!libressl? ( dev-libs/openssl:0= )
	libressl? ( dev-libs/libressl:0= )
	elibc_musl? ( sys-libs/libunwind )
	system-llvm? (
		${LLVM_DEPEND}
	)
"

RDEPEND="${DEPEND}
	app-eselect/eselect-rust
"

REQUIRED_USE="|| ( ${ALL_LLVM_TARGETS[*]} )
	miri? ( nightly )
	parallel-compiler? ( nightly )
	wasm? ( llvm_targets_WebAssembly )
	x86? ( cpu_flags_x86_sse2 )
"

# we don't use cmake.eclass, but can get a warnin -l
CMAKE_WARN_UNUSED_CLI=no

QA_FLAGS_IGNORED="
	usr/bin/.*-${PV}
	usr/lib.*/${P}/lib.*.so.*
	usr/lib.*/${P}/rustlib/.*/bin/.*
	usr/lib.*/${P}/rustlib/.*/lib/lib.*.so.*
"

QA_SONAME="
	usr/lib.*/${P}/lib.*.so.*
	usr/lib.*/${P}/rustlib/.*/lib/lib.*.so.*
"

# tests need a bit more work, currently they are causing multiple
# re-compilations and somewhat fragile.
RESTRICT="test"

PATCHES=(
	"${FILESDIR}"/0012-Ignore-broken-and-non-applicable-tests.patch
	"${FILESDIR}"/1.44.0-libressl.patch
)

S="${WORKDIR}/${MY_P}-src"

toml_usex() {
	usex "$1" true false
}

boostrap_rust_version_check() {
	# never call from pkg_pretend. eselect-rust may be not installed yet.
	local rustc_wanted="$(ver_cut 1).$(($(ver_cut 2) - 1))"
	local rustc_version=( $(eselect --brief rust show 2>/dev/null) )
	rustc_version=${rustc_version[0]#rust-bin-}
	rustc_version=${rustc_version#rust-}

	[[ -z "${rustc_version}" ]] && die "Failed to determine rustc version!"

	if ver_test "${rustc_version}" -lt "${rustc_wanted}" ; then
		eerror "Rust >=${rustc_wanted} is required"
		eerror "please run \'eselect rust\' and set correct rust version"
		die
	else
		einfo "Using rust ${rustc_version} to build"
	fi
}

pre_build_checks() {
	local M=6144
	M=$(( $(usex clippy 128 0) + ${M} ))
	M=$(( $(usex miri 128 0) + ${M} ))
	M=$(( $(usex rls 512 0) + ${M} ))
	M=$(( $(usex rustfmt 256 0) + ${M} ))
	M=$(( $(usex system-llvm 0 2048) + ${M} ))
	M=$(( $(usex wasm 256 0) + ${M} ))
	M=$(( $(usex debug 15 10) * ${M} / 10 ))
	eshopts_push -s extglob
	if is-flagq '-g?(gdb)?([1-9])'; then
		M=$(( 15 * ${M} / 10 ))
	fi
	eshopts_pop
	M=$(( $(usex system-bootstrap 0 1024) + ${M} ))
	M=$(( $(usex doc 256 0) + ${M} ))
	CHECKREQS_DISK_BUILD=${M}M check-reqs_pkg_${EBUILD_PHASE}
}

pkg_pretend() {
	pre_build_checks
}

pkg_setup() {
	pre_build_checks
	python-any-r1_pkg_setup
	use system-bootstrap && boostrap_rust_version_check

	# required to link agains system libs, otherwise
	# crates use bundled sources and compile own static version
	export LIBGIT2_SYS_USE_PKG_CONFIG=1
	export LIBSSH2_SYS_USE_PKG_CONFIG=1
	export PKG_CONFIG_ALLOW_CROSS=1

	if use system-llvm; then
		llvm_pkg_setup

		local llvm_config="$(get_llvm_prefix "$LLVM_MAX_SLOT")/bin/llvm-config"

		export LLVM_LINK_SHARED=1
		export RUSTFLAGS="${RUSTFLAGS} -Lnative=$("${llvm_config}" --libdir)"
	fi
}

src_prepare() {
	if ! use system-bootstrap; then
		local rust_stage0_root="${WORKDIR}"/rust-stage0
		local rust_stage0="rust-${RUST_STAGE0_VERSION}-$(rust_abi)"

		"${WORKDIR}/${rust_stage0}"/install.sh --disable-ldconfig \
			--destdir="${rust_stage0_root}" --prefix=/ || die
	fi

	default
}

src_configure() {
	local rust_target="" rust_targets="" arch_cflags

	# Collect rust target names to compile standard libs for all ABIs.
	for v in $(multilib_get_enabled_abi_pairs); do
		rust_targets="${rust_targets},\"$(rust_abi $(get_abi_CHOST ${v##*.}))\""
	done
	if use wasm; then
		rust_targets="${rust_targets},\"wasm32-unknown-unknown\""
		if use system-llvm; then
			# un-hardcode rust-lld linker for this target
			# https://bugs.gentoo.org/715348
			sed -i '/linker:/ s/rust-lld/wasm-ld/' src/librustc_target/spec/wasm32_base.rs || die
		fi
	fi
	rust_targets="${rust_targets#,}"

	local tools="\"cargo\","
	if use clippy; then
		tools="\"clippy\",$tools"
	fi
	if use miri; then
		tools="\"miri\",$tools"
	fi
	if use rls; then
		tools="\"rls\",\"analysis\",\"src\",$tools"
	fi
	if use rustfmt; then
		tools="\"rustfmt\",$tools"
	fi

	local rust_stage0_root
	if use system-bootstrap; then
		rust_stage0_root="$(rustc --print sysroot)"
	else
		rust_stage0_root="${WORKDIR}"/rust-stage0
	fi

	rust_target="$(rust_abi)"

	cat <<- EOF > "${S}"/config.toml
		[llvm]
		optimize = $(toml_usex !debug)
		release-debuginfo = $(toml_usex debug)
		assertions = $(toml_usex debug)
		ninja = true
		targets = "${LLVM_TARGETS// /;}"
		experimental-targets = ""
		link-shared = $(toml_usex system-llvm)
		[build]
		build = "${rust_target}"
		host = ["${rust_target}"]
		target = [${rust_targets}]
		cargo = "${rust_stage0_root}/bin/cargo"
		rustc = "${rust_stage0_root}/bin/rustc"
		docs = $(toml_usex doc)
		compiler-docs = $(toml_usex doc)
		submodules = false
		python = "${EPYTHON}"
		locked-deps = true
		vendor = true
		extended = true
		tools = [${tools}]
		verbose = 2
		sanitizers = false
		profiler = false
		cargo-native-static = false
		[install]
		prefix = "${EPREFIX}/usr"
		libdir = "$(get_libdir)/${P}"
		docdir = "share/doc/${PF}"
		mandir = "share/${P}/man"
		[rust]
		optimize = true
		debug = $(toml_usex debug)
		debug-assertions = $(toml_usex debug)
		debuginfo-level-rustc = 0
		backtrace = true
		incremental = false
		default-linker = "$(tc-getCC)"
		parallel-compiler = $(toml_usex parallel-compiler)
		channel = "$(usex nightly nightly stable)"
		rpath = false
		verbose-tests = true
		optimize-tests = $(toml_usex !debug)
		codegen-tests = true
		dist-src = false
		remap-debuginfo = true
		lld = $(usex system-llvm false $(toml_usex wasm))
		backtrace-on-ice = true
		jemalloc = false
		[dist]
		src-tarball = false
	EOF

	for v in $(multilib_get_enabled_abi_pairs); do
		rust_target=$(rust_abi $(get_abi_CHOST ${v##*.}))
		arch_cflags="$(get_abi_CFLAGS ${v##*.})"

		cat <<- EOF >> "${S}"/config.env
			CFLAGS_${rust_target}=${arch_cflags}
		EOF

		cat <<- EOF >> "${S}"/config.toml
			[target.${rust_target}]
			cc = "$(tc-getBUILD_CC)"
			cxx = "$(tc-getBUILD_CXX)"
			linker = "$(tc-getCC)"
			ar = "$(tc-getAR)"
		EOF
		# librustc_target/spec/linux_musl_base.rs sets base.crt_static_default = true;
		if use elibc_musl; then
			cat <<- EOF >> "${S}"/config.toml
				crt-static = false
			EOF
		fi
		if use system-llvm; then
			cat <<- EOF >> "${S}"/config.toml
				llvm-config = "$(get_llvm_prefix "${LLVM_MAX_SLOT}")/bin/llvm-config"
			EOF
		fi
	done
	if use wasm; then
		cat <<- EOF >> "${S}"/config.toml
			[target.wasm32-unknown-unknown]
			linker = "$(usex system-llvm lld rust-lld)"
		EOF
	fi

	if [[ -n ${I_KNOW_WHAT_I_AM_DOING_CROSS} ]]; then #whitespace intentionally shifted below
	# experimental cross support
	# discussion: https://bugs.gentoo.org/679878
	# TODO: c*flags, clang, system-llvm, cargo.eclass target support
	# it would be much better if we could split out stdlib
	# complilation to separate ebuild and abuse CATEGORY to
	# just install to /usr/lib/rustlib/<target>

	# extra targets defined as a bash array
	# spec format:  <LLVM target>:<rust-target>:<CTARGET>
	# best place would be /etc/portage/env/dev-lang/rust
	# Example:
	# RUST_CROSS_TARGETS=(
	#	"AArch64:aarch64-unknown-linux-gnu:aarch64-unknown-linux-gnu"
	# )
	# no extra hand holding is done, no target transformations, all
	# values are passed as-is with just basic checks, so it's up to user to supply correct values
	# valid rust targets can be obtained with
	# 	rustc --print target-list
	# matching cross toolchain has to be installed
	# matching LLVM_TARGET has to be enabled for both rust and llvm (if using system one)
	# only gcc toolchains installed with crossdev are checked for now.

	# BUG: we can't pass host flags to cross compiler, so just filter for now
	# BUG: this should be more fine-grained.
	filter-flags '-mcpu=*' '-march=*' '-mtune=*'

	local cross_target_spec
	for cross_target_spec in "${RUST_CROSS_TARGETS[@]}";do
		# extracts first element form <LLVM target>:<rust-target>:<CTARGET>
		local cross_llvm_target="${cross_target_spec%%:*}"
		# extracts toolchain triples, <rust-target>:<CTARGET>
		local cross_triples="${cross_target_spec#*:}"
		# extracts first element after before : separator
		local cross_rust_target="${cross_triples%%:*}"
		# extracts last element after : separator
		local cross_toolchain="${cross_triples##*:}"
		use llvm_targets_${cross_llvm_target} || die "need llvm_targets_${cross_llvm_target} target enabled"
		command -v ${cross_toolchain}-gcc > /dev/null 2>&1 || die "need ${cross_toolchain} cross toolchain"

		cat <<- EOF >> "${S}"/config.toml
			[target.${cross_rust_target}]
			cc = "${cross_toolchain}-gcc"
			cxx = "${cross_toolchain}-g++"
			linker = "${cross_toolchain}-gcc"
			ar = "${cross_toolchain}-ar"
		EOF
		if use system-llvm; then
			cat <<- EOF >> "${S}"/config.toml
				llvm-config = "$(get_llvm_prefix "${LLVM_MAX_SLOT}")/bin/llvm-config"
			EOF
		fi

		# append cross target to "normal" target list
		# example 'target = ["powerpc64le-unknown-linux-gnu"]'
		# becomes 'target = ["powerpc64le-unknown-linux-gnu","aarch64-unknown-linux-gnu"]'

		rust_targets="${rust_targets},\"${cross_rust_target}\""
		sed -i "/^target = \[/ s#\[.*\]#\[${rust_targets}\]#" config.toml || die

		ewarn
		ewarn "Enabled ${cross_rust_target} rust target"
		ewarn "Using ${cross_toolchain} cross toolchain"
		ewarn
		if ! has_version -b 'sys-devel/binutils[multitarget]' ; then
			ewarn "'sys-devel/binutils[multitarget]' is not installed"
			ewarn "'strip' will be unable to strip cross libraries"
			ewarn "cross targets will be installed with full debug information"
			ewarn "enable 'multitarget' USE flag for binutils to be able to strip object files"
			ewarn
			ewarn "Alternatively llvm-strip can be used, it supports stripping any target"
			ewarn "define STRIP=\"llvm-strip\" to use it (experimental)"
			ewarn
		fi
	done
	fi # I_KNOW_WHAT_I_AM_DOING_CROSS

	einfo "Rust configured with the following settings:"
	cat "${S}"/config.toml || die
}

src_compile() {
	env $(cat "${S}"/config.env) RUST_BACKTRACE=1\
		"${EPYTHON}" ./x.py build -vv --config="${S}"/config.toml -j$(makeopts_jobs) || die
}

src_test() {
	env $(cat "${S}"/config.env) RUST_BACKTRACE=1\
		"${EPYTHON}" ./x.py test -vv --config="${S}"/config.toml -j$(makeopts_jobs) --no-doc --no-fail-fast \
		src/test/codegen \
		src/test/codegen-units \
		src/test/compile-fail \
		src/test/incremental \
		src/test/mir-opt \
		src/test/pretty \
		src/test/run-fail \
		src/test/run-make \
		src/test/run-make-fulldeps \
		src/test/ui \
		src/test/ui-fulldeps || die
}

src_install() {
	env $(cat "${S}"/config.env) DESTDIR="${D}" \
		"${EPYTHON}" ./x.py install -vv --config="${S}"/config.toml || die

	# bug #689562, #689160
	rm "${D}/etc/bash_completion.d/cargo" || die
	rmdir "${D}"/etc{/bash_completion.d,} || die
	dobashcomp build/tmp/dist/cargo-image/etc/bash_completion.d/cargo

	# Copy shared library versions of standard libraries for all targets
	# into the system's abi-dependent lib directories because the rust
	# installer only does so for the native ABI.

	local abi_libdir rust_target
	for v in $(multilib_get_enabled_abi_pairs); do
		if [ ${v##*.} = ${DEFAULT_ABI} ]; then
			continue
		fi
		abi_libdir=$(get_abi_LIBDIR ${v##*.})
		rust_target=$(rust_abi $(get_abi_CHOST ${v##*.}))
		mkdir -p "${ED}/usr/${abi_libdir}/${P}"
		cp "${ED}/usr/$(get_libdir)/${P}/rustlib/${rust_target}/lib"/*.so \
		   "${ED}/usr/${abi_libdir}/${P}" || die
	done
}

pkg_postinst() {
	elog "Rust installs a helper script for calling GDB and LLDB,"
	elog "for your convenience it is installed under /usr/bin/rust-{gdb,lldb}-${PV}."

	if has_version app-editors/emacs; then
		elog "install app-emacs/rust-mode to get emacs support for rust."
	fi

	if has_version app-editors/gvim || has_version app-editors/vim; then
		elog "install app-vim/rust-vim to get vim support for rust."
	fi

	if use elibc_musl; then
		ewarn "${PN} on *-musl targets is configured with crt-static"
		ewarn ""
		ewarn "you will need to set RUSTFLAGS=\"-C target-feature=-crt-static\" in make.conf"
		ewarn "to use it with portage, otherwise you may see failures like"
		ewarn "error: cannot produce proc-macro for serde_derive v1.0.98 as the target "
		ewarn "x86_64-unknown-linux-musl does not support these crate types"
	fi
}