build.sh: clean subsequent build step if sysroot changes

Author: tylerwhall

rust/build.sh

@@ -5,30 +5,38 @@ VERSION="+nightly-2019-05-22"
 CARGO_ARGS="${VERSION} -v build --target=${RUST_TARGET} --release"
 
 publish_sysroot() {
+    local CLEAN_DIR_IF_CHANGED=$1
+    shift
     local SYSROOT=$1
+    shift
     local SYSROOT_LIB="${SYSROOT}/lib/rustlib/${RUST_TARGET}/lib"
     local SYSROOT_LIB_HOST="${SYSROOT}/lib/rustlib/${HOST}/lib"
-    shift
-    rm -rf ${SYSROOT}
     mkdir -p ${SYSROOT_LIB} ${SYSROOT_LIB_HOST}
+    mkdir -p ${SYSROOT_LIB}-new ${SYSROOT_LIB_HOST}-new
 
     for src in $@; do
-        cp -a $src/${RUST_TARGET}/release/deps/. ${SYSROOT_LIB}
-        cp -a $src/release/deps/. ${SYSROOT_LIB_HOST}
+        cp -a $src/${RUST_TARGET}/release/deps/. ${SYSROOT_LIB}-new
+        cp -a $src/release/deps/. ${SYSROOT_LIB_HOST}-new
     done
+    if ! diff -qr ${SYSROOT_LIB} ${SYSROOT_LIB}-new || ! diff -qr ${SYSROOT_LIB_HOST} ${SYSROOT_LIB_HOST}-new; then
+        rm -rf ${CLEAN_DIR_IF_CHANGED}
+    fi
+    rm -r ${SYSROOT_LIB} ${SYSROOT_LIB_HOST}
+    mv ${SYSROOT_LIB}-new ${SYSROOT_LIB}
+    mv ${SYSROOT_LIB_HOST}-new ${SYSROOT_LIB_HOST}
 }
 
 # Build std
 cargo ${CARGO_ARGS} \
     --target-dir=${SYSROOT_BUILD}-stage1 \
     --manifest-path=./sysroot-stage1/Cargo.toml -p std
-publish_sysroot ${SYSROOT}-stage1 ${SYSROOT_BUILD}-stage1
+publish_sysroot ${SYSROOT_BUILD}-stage2 ${SYSROOT}-stage1 ${SYSROOT_BUILD}-stage1
 # Build Zephyr crates
 RUSTFLAGS="${RUSTFLAGS} --sysroot ${SYSROOT}-stage1" cargo ${CARGO_ARGS} \
     --target-dir=${SYSROOT_BUILD}-stage2 \
     --manifest-path=./sysroot-stage2/Cargo.toml
 
-publish_sysroot ${SYSROOT} ${SYSROOT_BUILD}-stage1 ${SYSROOT_BUILD}-stage2
+publish_sysroot ${APP_BUILD} ${SYSROOT} ${SYSROOT_BUILD}-stage1 ${SYSROOT_BUILD}-stage2
 
 export RUSTFLAGS="${RUSTFLAGS} --sysroot ${SYSROOT}"
 cargo ${CARGO_ARGS} --target-dir=${APP_BUILD} --manifest-path=${CARGO_MANIFEST}