1 files changed, 57 insertions, 0 deletions
diff --git a/third_party/rust/crossbeam-epoch/build.rs b/third_party/rust/crossbeam-epoch/build.rs
new file mode 100644
index 0000000000..978141aa52
--- /dev/null
+++ b/third_party/rust/crossbeam-epoch/build.rs
@@ -0,0 +1,57 @@
+// The rustc-cfg listed below are considered public API, but it is *unstable*
+// and outside of the normal semver guarantees:
+//
+// - `crossbeam_no_atomic_cas`
+//      Assume the target does *not* support atomic CAS operations.
+//      This is usually detected automatically by the build script, but you may
+//      need to enable it manually when building for custom targets or using
+//      non-cargo build systems that don't run the build script.
+//
+// With the exceptions mentioned above, the rustc-cfg emitted by the build
+// script are *not* public API.
+
+#![warn(rust_2018_idioms)]
+
+use std::env;
+
+include!("no_atomic.rs");
+include!("build-common.rs");
+
+fn main() {
+    let target = match env::var("TARGET") {
+        Ok(target) => convert_custom_linux_target(target),
+        Err(e) => {
+            println!(
+                "cargo:warning={}: unable to get TARGET environment variable: {}",
+                env!("CARGO_PKG_NAME"),
+                e
+            );
+            return;
+        }
+    };
+
+    let cfg = match autocfg::AutoCfg::new() {
+        Ok(cfg) => cfg,
+        Err(e) => {
+            println!(
+                "cargo:warning={}: unable to determine rustc version: {}",
+                env!("CARGO_PKG_NAME"),
+                e
+            );
+            return;
+        }
+    };
+
+    // Note that this is `no_`*, not `has_*`. This allows treating as the latest
+    // stable rustc is used when the build script doesn't run. This is useful
+    // for non-cargo build systems that don't run the build script.
+    if NO_ATOMIC_CAS.contains(&&*target) {
+        println!("cargo:rustc-cfg=crossbeam_no_atomic_cas");
+    }
+
+    if !cfg.probe_rustc_version(1, 61) {
+        println!("cargo:rustc-cfg=crossbeam_no_const_fn_trait_bound");
+    }
+
+    println!("cargo:rerun-if-changed=no_atomic.rs");
+}