[gentoo-dev] [PATCH] cargo.eclass: add cargo_live_src_unpack()

[Georgy Yakovlev]

This function will allow using 'cargo fetch' during src_fetch
Since only new cargo supports that, all live packages will
have to depend on >=rust-1.37.0

This enables us to ship live rust packages,
cargo fetch will download all crates and vendor them for offline
phases.

here's an example of src_unpack()

src_unpack() {
        if [[ "${PV}" == *9999* ]]; then
                git-r3_src_unpack
                cargo_live_src_unpack
        else
                cargo_src_unpack
        fi
}

Signed-off-by: Georgy Yakovlev <gyakovlev@g.o>
---
 eclass/cargo.eclass | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/eclass/cargo.eclass b/eclass/cargo.eclass
index b16e0e9d633..44d11cdb838 100644
--- a/eclass/cargo.eclass
+++ b/eclass/cargo.eclass
@@ -12,7 +12,12 @@
 if [[ -z ${_CARGO_ECLASS} ]]; then
 _CARGO_ECLASS=1
 
-CARGO_DEPEND="virtual/cargo"
+if [[ ${PV} == *9999* ]]; then
+	# we need at least this for cargo vendor subommand
+	CARGO_DEPEND=">=virtual/cargo-1.37.0"
+else
+	CARGO_DEPEND="virtual/cargo"
+fi
 
 case ${EAPI} in
 	6) DEPEND="${CARGO_DEPEND}";;
@@ -97,6 +102,26 @@ cargo_src_unpack() {
 	cargo_gen_config
 }
 
+# @FUNCTION: cargo_live_src_unpack
+# @DESCRIPTION:
+# Runs 'cargo fetch' and vendors downloaded crates for offline use, used in live ebuilds
+
+cargo_live_src_unpack() {
+	debug-print-function ${FUNCNAME} "$@"
+
+	[[ "${PV}" == *9999* ]] || die "${FUNCNAME} only allowed in live/9999 ebuilds"
+	[[ "${EBUILD_PHASE}" == unpack ]] || die "${FUNCNAME} only allowed in src_unpack"
+
+	mkdir -p "${S}" || die
+
+	pushd "${S}" > /dev/null || die
+	CARGO_HOME="${ECARGO_HOME}" cargo fetch || die
+	CARGO_HOME="${ECARGO_HOME}" cargo vendor "${ECARGO_VENDOR}" || die
+	popd > /dev/null || die
+
+	cargo_gen_config
+}
+
 # @FUNCTION: cargo_gen_config
 # @DESCRIPTION:
 # Generate the $CARGO_HOME/config necessary to use our local registry
-- 
2.23.0