1 files changed, 16 insertions, 0 deletions
diff --git a/syn-mid/examples/const_fn_test/build.rs b/syn-mid/examples/const_fn_test/build.rs
new file mode 100644
index 0000000..bebf234
--- /dev/null
+++ b/syn-mid/examples/const_fn_test/build.rs
@@ -0,0 +1,16 @@
+use std::{env, process::Command};
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    if is_nightly() {
+        println!("cargo:rustc-cfg=nightly");
+    }
+}
+
+fn is_nightly() -> bool {
+    env::var_os("RUSTC")
+        .and_then(|rustc| Command::new(rustc).arg("--version").output().ok())
+        .and_then(|output| String::from_utf8(output.stdout).ok())
+        .map_or(false, |version| version.contains("nightly"))
+}