1 files changed, 39 insertions, 0 deletions
diff --git a/third_party/rust/failure_derive/build.rs b/third_party/rust/failure_derive/build.rs
new file mode 100644
index 0000000000..8f220458d2
--- /dev/null
+++ b/third_party/rust/failure_derive/build.rs
@@ -0,0 +1,39 @@
+use std::env;
+use std::process::Command;
+use std::str;
+use std::str::FromStr;
+
+fn main() {
+    if rustc_has_dyn_trait() {
+        println!("cargo:rustc-cfg=has_dyn_trait");
+    }
+}
+
+fn rustc_has_dyn_trait() -> bool {
+    let rustc = match env::var_os("RUSTC") {
+        Some(rustc) => rustc,
+        None => return false,
+    };
+
+    let output = match Command::new(rustc).arg("--version").output() {
+        Ok(output) => output,
+        Err(_) => return false,
+    };
+
+    let version = match str::from_utf8(&output.stdout) {
+        Ok(version) => version,
+        Err(_) => return false,
+    };
+
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return true;
+    }
+
+    let next = match pieces.next() {
+        Some(next) => next,
+        None => return false,
+    };
+
+    u32::from_str(next).unwrap_or(0) >= 27
+}