1 files changed, 30 insertions, 0 deletions
diff --git a/js/src/frontend/smoosh/build.rs b/js/src/frontend/smoosh/build.rs
new file mode 100644
index 0000000000..3ae2cf54cd
--- /dev/null
+++ b/js/src/frontend/smoosh/build.rs
@@ -0,0 +1,30 @@
+use jsparagus::stencil::opcode_info;
+
+fn compare(name: &str, orig: &str, copied: &str) {
+    if copied != orig {
+        panic!(
+            "{} is out of sync. \
+                It's possible that the bytecode generated by jsparagus is \
+                based on older opcodes. Please run \
+                update_stencil.py in jsparagus. \
+                You can disable this check by setting \
+                JS_SMOOSH_DISABLE_OPCODE_CHECK environment variable.",
+            name
+        );
+    }
+}
+
+fn main() {
+    match std::env::var("JS_SMOOSH_DISABLE_OPCODE_CHECK") {
+        Ok(_) => {
+            return;
+        }
+        Err(_) => {}
+    };
+
+    compare(
+        "Opcodes.h",
+        include_str!("../../vm/Opcodes.h"),
+        opcode_info::get_opcodes_source(),
+    );
+}