chore(ffi): only backup hyper.h when passing --verify (#3800)

capi/gen_header.sh

@@ -11,11 +11,14 @@
 set -e
 
 CAPI_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+header_file="$CAPI_DIR/include/hyper.h"
 header_file_backup="$CAPI_DIR/include/hyper.h.backup"
-
+verify_flag=$1
 function cleanup {
     rm -rf "$WORK_DIR" || true
-    rm "$header_file_backup" || true
+    if [[ "--verify" == "$verify_flag" ]]; then
+        rm "$header_file_backup" || true
+    fi
 }
 
 trap cleanup EXIT
@@ -28,7 +31,10 @@ if [[ ! "$WORK_DIR" || ! -d "$WORK_DIR" ]]; then
     exit 1
 fi
 
-cp "$CAPI_DIR/include/hyper.h" "$header_file_backup"
+# backup hyper.h
+if [[ "--verify" == "$verify_flag" ]]; then
+    cp "$header_file" "$header_file_backup"
+fi
 
 # Expand just the ffi module
 if ! RUSTFLAGS='--cfg hyper_unstable_ffi' cargo expand --features client,http1,http2,ffi ::ffi 2> $WORK_DIR/expand_stderr.err > $WORK_DIR/expanded.rs; then
@@ -39,13 +45,13 @@ fi
 if ! cbindgen \
     --config "$CAPI_DIR/cbindgen.toml" \
     --lockfile "$CAPI_DIR/../Cargo.lock" \
-    --output "$CAPI_DIR/include/hyper.h" \
+    --output "$header_file" \
     "${@}"\
     $WORK_DIR/expanded.rs 2> $WORK_DIR/cbindgen_stderr.err; then
     bindgen_exit_code=$?
-    if [[ "--verify" == "$1" ]]; then
+    if [[ "--verify" == "$verify_flag" ]]; then
         echo "Changes from previous header (old < > new)"
-        diff -u "$header_file_backup" "$CAPI_DIR/include/hyper.h"
+        diff -u "$header_file_backup" "$header_file"
     else
         echo "cbindgen failed:"
         cat $WORK_DIR/cbindgen_stderr.err