brief old rust -> slotted rust porting guide

file_943706.txt (text/plain), 2.89 KB, created by Matt Jolly on 2024-11-21 23:38:02 UTC

rust porting notes (a slightly butchered example for 1.54.0)

# Do not do llvm-r1 / LLVM_COMPAT for < LLVM 16; instead drop
# use=system-llvm

# First, Update rust.eclass with the new rust version. LLVM_RUST_MAP, RUST_SLOTS_ORDERED
# Then add dev-lang/rust-bin; this is basically just adding any required blockers, updating depends, etc
# Finally we can use rust-bin to bootstrap rust (n.b. If you have the previous minor version you can bootstrap using that)

LLVM_COMPAT=( 12 ) # check https://releases.rs/docs/${PV}; not requried if <16

RUST_MAX_VER=${PV}
# It's fine if this is older than we support, the rust eclass will set it to the oldest supported version
RUST_MIN_VER="$(ver_cut 1).$(($(ver_cut 2) - 1)).0"

# If required for a crate that just doesn't work:
OVERRIDE_CRATES=(
    openssl@0.10.35
	openssl-sys@0.9.65
)

inherit -bash_completion-r1 llvm-r1 rust cargo (if OVERRIDE_CRATES, else rust eclass is sufficient)


drop RUST_STAGE0_VERSION
S="${WORKDIR}/${MY_P}-src" # remove from below, fixup other variable ordering QA

USE= drop system-bootstrap

SLOT="${PV}" #AFTER LICENSE

# llvm-r1 only
LLVM_DEPEND=()
# splitting usedeps needed to avoid CI/pkgcheck's UncheckableDep limitation
for _x in "${ALL_LLVM_TARGETS[@]}"; do
	LLVM_DEPEND+=( "	${_x}? ( $(llvm_gen_dep "sys-devel/llvm:\${LLVM_SLOT}[${_x}]") )" )
done
LLVM_DEPEND+=( "	wasm? ( $(llvm_gen_dep 'sys-devel/lld:${LLVM_SLOT}') )" )
LLVM_DEPEND+=( "	$(llvm_gen_dep 'sys-devel/llvm:${LLVM_SLOT}')" )

# Slotted rust bdepends

RDEPEND+=
    dev-lang/rust-common
	!dev-lang/rust:stable
	!dev-lang/rust-bin:stable

pre_build_checks() {
    local M=5120 (4096 + 1024)
    ...
    drop system-bootstrap
}

# Grab these from (probably) https://gitweb.gentoo.org/fork/llvm-project.git/log/llvm/include?h=gentoo-15.0.7-r7 as required
# We only need essential ones, they should stay the same across a llvm major ver
PATCHES=(
    ...
    "${FILESDIR}/llvm/##/foo.patch
)

bootstrap_rust_version_check () {
    # purge this
}

pkg_setup() {

    - use system-bootstrap && bootstrap_rust_version_check
    ...
    llvm -> llvm-r1_pkg_setup (or drop)
    rust_pkg_setup
}

src_unpack() {
	verify-sig_src_unpack
	cargo_src_unpack
	# Vendored sources here override crates-io sources from cargo eclass.
	# Just chop the head off the config file so that cargo stops complaining about it
	# being defined in two places. We're only using the eclass for overrides anyway.
	tail -n +7 "${ECARGO_HOME}"/config.toml > "${ECARGO_HOME}"/config.toml
}
src_configure() {
    # if required (LLVM < 16, probably)
    append-cxxflags -std=gnu++17 or gnu++14
    # force system-bootstrap path in conditionals
}

src_install() {
    -newbashcomp ...

    # Update this for slotted rust path
    newenvd - "50${P}" <<-_EOF_
		LDPATH="${EPREFIX}/usr/lib/rust/lib-${PV}"
		MANPATH="${EPREFIX}/usr/lib/rust/man-${PV}"
		. . .
}