1 files changed, 33 insertions, 0 deletions
diff --git a/third_party/rust/autocfg/tests/rustflags.rs b/third_party/rust/autocfg/tests/rustflags.rs
new file mode 100644
index 0000000000..f054546681
--- /dev/null
+++ b/third_party/rust/autocfg/tests/rustflags.rs
@@ -0,0 +1,33 @@
+extern crate autocfg;
+
+use std::env;
+
+/// Tests that autocfg uses the RUSTFLAGS or CARGO_ENCODED_RUSTFLAGS
+/// environment variables when running rustc.
+#[test]
+fn test_with_sysroot() {
+    // Use the same path as this test binary.
+    let dir = env::current_exe().unwrap().parent().unwrap().to_path_buf();
+    env::set_var("OUT_DIR", &format!("{}", dir.display()));
+
+    // If we have encoded rustflags, they take precedence, even if empty.
+    env::set_var("CARGO_ENCODED_RUSTFLAGS", "");
+    env::set_var("RUSTFLAGS", &format!("-L {}", dir.display()));
+    let ac = autocfg::AutoCfg::new().unwrap();
+    assert!(ac.probe_sysroot_crate("std"));
+    assert!(!ac.probe_sysroot_crate("autocfg"));
+
+    // Now try again with useful encoded args.
+    env::set_var(
+        "CARGO_ENCODED_RUSTFLAGS",
+        &format!("-L\x1f{}", dir.display()),
+    );
+    let ac = autocfg::AutoCfg::new().unwrap();
+    assert!(ac.probe_sysroot_crate("autocfg"));
+
+    // Try the old-style RUSTFLAGS, ensuring HOST != TARGET.
+    env::remove_var("CARGO_ENCODED_RUSTFLAGS");
+    env::set_var("HOST", "lol");
+    let ac = autocfg::AutoCfg::new().unwrap();
+    assert!(ac.probe_sysroot_crate("autocfg"));
+}