1 files changed, 24 insertions, 0 deletions
diff --git a/third_party/rust/slab/build.rs b/third_party/rust/slab/build.rs
new file mode 100644
index 0000000000..b60351aaf2
--- /dev/null
+++ b/third_party/rust/slab/build.rs
@@ -0,0 +1,24 @@
+fn main() {
+    let cfg = match autocfg::AutoCfg::new() {
+        Ok(cfg) => cfg,
+        Err(e) => {
+            // If we couldn't detect the compiler version and features, just
+            // print a warning. This isn't a fatal error: we can still build
+            // Slab, we just can't enable cfgs automatically.
+            println!(
+                "cargo:warning=slab: failed to detect compiler features: {}",
+                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 !cfg.probe_rustc_version(1, 39) {
+        println!("cargo:rustc-cfg=slab_no_const_vec_new");
+    }
+    if !cfg.probe_rustc_version(1, 46) {
+        println!("cargo:rustc-cfg=slab_no_track_caller");
+    }
+}