1 files changed, 23 insertions, 0 deletions
diff --git a/third_party/rust/unicase/build.rs b/third_party/rust/unicase/build.rs
new file mode 100644
index 0000000000..6b22ab5f32
--- /dev/null
+++ b/third_party/rust/unicase/build.rs
@@ -0,0 +1,23 @@
+extern crate version_check as rustc;
+
+fn main() {
+    if is_rustc_at_least("1.5.0") {
+        println!("cargo:rustc-cfg=__unicase__iter_cmp");
+    }
+
+    if is_rustc_at_least("1.13.0") {
+        println!("cargo:rustc-cfg=__unicase__default_hasher");
+    }
+
+    if is_rustc_at_least("1.31.0") {
+        println!("cargo:rustc-cfg=__unicase__const_fns");
+    }
+
+    if is_rustc_at_least("1.36.0") {
+        println!("cargo:rustc-cfg=__unicase__core_and_alloc");
+    }
+}
+
+fn is_rustc_at_least(v: &str) -> bool {
+    rustc::is_min_version(v).unwrap_or(true)
+}