[PATCH v2] rust: respect CARGO_BUILD_TARGET when locating build output

[James Le Cuirot <chewi@gentoo.org>]

When cross-compiling, Cargo always writes to a target-tuple subdirectory
determined by CARGO_BUILD_TARGET, even when it matches the native tuple.
The build looked in $BUILD_DIR/$BUILD_TYPE directly, so it failed to
locate the freshly built library.

Respect CARGO_BUILD_TARGET in the output path so the correct artifact
is located.

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

> Nowhere in the above description I see mention of meson, but the
> patch is only to cargo-meson that is referenced by src/meson.build
> which invites a few questions:
>
>  * Does "make" work fine without any change similar to this?
>
>  * Shouldn't the commit title say "meson" somewhere if this change
>    is only for "meson" driven build?

Good point. I hadn't realised that Make is still supported. I have now
amended the Makefile and tested both the native and cross cases.

 Makefile           | 4 ++--
 src/cargo-meson.sh | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 1cec251..5cd5889 100644
--- a/Makefile
+++ b/Makefile
@@ -940,9 +940,9 @@ TEST_SHELL_PATH = $(SHELL_PATH)
 LIB_FILE = libgit.a

 ifdef DEBUG
-RUST_TARGET_DIR = target/debug
+RUST_TARGET_DIR = target/$(CARGO_BUILD_TARGET)/debug
 else
-RUST_TARGET_DIR = target/release
+RUST_TARGET_DIR = target/$(CARGO_BUILD_TARGET)/release
 endif

 ifeq ($(uname_S),Windows)
diff --git a/src/cargo-meson.sh b/src/cargo-meson.sh
index 75f3cd1..3a558aa 100755
--- a/src/cargo-meson.sh
+++ b/src/cargo-meson.sh
@@ -38,7 +38,7 @@ then
 	exit $RET
 fi

-if ! cmp "$BUILD_DIR/$BUILD_TYPE/$LIBNAME" "$BUILD_DIR/libgitcore.a" >/dev/null 2>&1
+if ! cmp "$BUILD_DIR/${CARGO_BUILD_TARGET-}/$BUILD_TYPE/$LIBNAME" "$BUILD_DIR/libgitcore.a" >/dev/null 2>&1
 then
-	cp "$BUILD_DIR/$BUILD_TYPE/$LIBNAME" "$BUILD_DIR/libgitcore.a"
+	cp "$BUILD_DIR/${CARGO_BUILD_TARGET-}/$BUILD_TYPE/$LIBNAME" "$BUILD_DIR/libgitcore.a"
 fi
--
2.55.0