1 files changed, 13 insertions, 0 deletions
diff --git a/library/stdarch/crates/assert-instr-macro/build.rs b/library/stdarch/crates/assert-instr-macro/build.rs
new file mode 100644
index 000000000..01ae79660
--- /dev/null
+++ b/library/stdarch/crates/assert-instr-macro/build.rs
@@ -0,0 +1,13 @@
+use std::env;
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    let opt_level = env::var("OPT_LEVEL")
+        .ok()
+        .and_then(|s| s.parse().ok())
+        .unwrap_or(0);
+    let profile = env::var("PROFILE").unwrap_or_default();
+    if profile == "release" || opt_level >= 2 {
+        println!("cargo:rustc-cfg=optimized");
+    }
+}