cargo.eclass: Add cargo_target_dir helper function

Several Cargo-based ebuilds cannot use cargo_src_install for various
reasons and manually install binaries from within the target directory
instead. It is common to see `target/$(usex debug debug release)`, but
this lacks the target ABI when cross-compiling, so provide a helper
function.

There are some multilib Cargo-based ebuilds that always set the target
ABI, even when not cross-compiling. It would be simpler to do this in
general, so once ebuilds have been updated to use this new helper, I
might change the eclass again accordingly.

Signed-off-by: James Le Cuirot <chewi@gentoo.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/eclass/cargo.eclass b/eclass/cargo.eclass
index 548aaef3ed69..7db34efb4e17 100644
--- a/eclass/cargo.eclass
+++ b/eclass/cargo.eclass
@@ -319,6 +319,16 @@ _cargo_gen_git_config() {
 	fi
 }
 
+# @FUNCTION: cargo_target_dir
+# @DESCRIPTION:
+# Return the directory within target that contains the build, e.g.
+# target/aarch64-unknown-linux-gnu/release.
+cargo_target_dir() {
+	local abi
+	tc-is-cross-compiler && abi=/$(rust_abi)
+	echo "${CARGO_TARGET_DIR:-target}${abi}/$(usex debug debug release)"
+}
+
 # @FUNCTION: cargo_src_unpack
 # @DESCRIPTION:
 # Unpacks the package and the cargo registry.