1 files changed, 30 insertions, 0 deletions
diff --git a/third_party/rust/darling_core/src/options/forward_attrs.rs b/third_party/rust/darling_core/src/options/forward_attrs.rs
new file mode 100644
index 0000000000..ac9f4e1a84
--- /dev/null
+++ b/third_party/rust/darling_core/src/options/forward_attrs.rs
@@ -0,0 +1,30 @@
+use crate::ast::NestedMeta;
+use crate::util::PathList;
+use crate::{FromMeta, Result};
+
+/// A rule about which attributes to forward to the generated struct.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ForwardAttrs {
+    All,
+    Only(PathList),
+}
+
+impl ForwardAttrs {
+    /// Returns `true` if this will not forward any attributes.
+    pub fn is_empty(&self) -> bool {
+        match *self {
+            ForwardAttrs::All => false,
+            ForwardAttrs::Only(ref list) => list.is_empty(),
+        }
+    }
+}
+
+impl FromMeta for ForwardAttrs {
+    fn from_word() -> Result<Self> {
+        Ok(ForwardAttrs::All)
+    }
+
+    fn from_list(nested: &[NestedMeta]) -> Result<Self> {
+        Ok(ForwardAttrs::Only(PathList::from_list(nested)?))
+    }
+}