build: vendor Rust crate dependencies

third_party/crates/anyhow-1.0.104/tests/test_backtrace.rs

@@ -0,0 +1,15 @@
+#![allow(clippy::let_underscore_untyped)]
+
+#[rustversion::not(nightly)]
+#[ignore = "requires nightly"]
+#[test]
+fn test_backtrace() {}
+
+#[rustversion::nightly]
+#[test]
+fn test_backtrace() {
+    use anyhow::anyhow;
+
+    let error = anyhow!("oh no!");
+    let _ = error.backtrace();
+}