[PATCH] rust: Use llvm-config from native llvm-rust on rust target builds

[Khem Raj <raj.khem@gmail.com>]

target rust recipe builds ( cross compile ) calls llvm-config from
target sysroot which works ok as long as C++ runtime it needs is
available on build host e.g. libstdc++ etc. which is commonly the
case, however when using clang and llvm runtime this falters since
it should be using libc++ from native sysroot and if this does not
exist on build machine this fails to find libc++ shared object and
llvm-config fails to run. This ensures that llvm-config version in
use is correctly relocated and can use shared libraries from native
sysroot correctly. Adding ORIGIN to sysroot will look for the .so in
same dir as the binary and there is the libc++.so.1 copied in place

Fixes rust build with clang compiler.

| /mnt/b/yoe/master/build/tmp/work/riscv64-yoe-linux/rust/1.74.1/recipe-sysroot/usr/lib/llvm-rust/bin/llvm-config: error while loading shared libraries: libc++.so.1: cannot open shared object file: No such file or director
y
| thread 'main' panicked at llvm.rs:551:19:
| command did not execute successfully: "/mnt/b/yoe/master/build/tmp/work/riscv64-yoe-linux/rust/1.74.1/recipe-sysroot/usr/lib/llvm-rust/bin/llvm-config" "--version"
| expected success, got: exit status: 127

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 meta/recipes-devtools/rust/rust_1.74.1.bb | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/meta/recipes-devtools/rust/rust_1.74.1.bb b/meta/recipes-devtools/rust/rust_1.74.1.bb
index 30543ada7db..2dffe009827 100644
--- a/meta/recipes-devtools/rust/rust_1.74.1.bb
+++ b/meta/recipes-devtools/rust/rust_1.74.1.bb
@@ -198,9 +198,13 @@ rust_runx () {
     # Copy the natively built llvm-config into the target so we can run it. Horrible,
     # but works!
     if [ ${RUST_ALTERNATE_EXE_PATH_NATIVE} != ${RUST_ALTERNATE_EXE_PATH} -a ! -f ${RUST_ALTERNATE_EXE_PATH} ]; then
-        mkdir -p `dirname ${RUST_ALTERNATE_EXE_PATH}`
+        tgtdir=`dirname ${RUST_ALTERNATE_EXE_PATH}`
+        mkdir -p ${tgtdir}
         cp ${RUST_ALTERNATE_EXE_PATH_NATIVE} ${RUST_ALTERNATE_EXE_PATH}
-        chrpath -d ${RUST_ALTERNATE_EXE_PATH}
+        if [ -e ${STAGING_LIBDIR_NATIVE}/libc++.so.1 ]; then
+            cp ${STAGING_LIBDIR_NATIVE}/libc++.so.1 ${tgtdir}/
+        fi
+        chrpath -r \$ORIGIN ${RUST_ALTERNATE_EXE_PATH}
     fi
 
     oe_cargo_fix_env
-- 
2.43.0