simple polymorphic extern_spec for Option<T>

flux_support/src/lib.rs

@@ -178,3 +178,22 @@ impl<T> [T] {
 #[extern_spec(core::ptr)]
 #[refined_by(n: int)]
 struct NonNull<T>;
+
+
+#[extern_spec]
+#[refined_by(b: bool)]
+enum Option<T> {
+    #[flux_rs::variant(Option<T>[false])]
+    None,
+    #[flux_rs::variant({T} -> Option<T>[true])]
+    Some(T),
+}
+
+#[extern_spec]
+impl<T> Option<T> {
+    #[sig(fn(&Option<T>[@b]) -> bool[b])]
+    const fn is_some(&self) -> bool;
+
+    #[sig(fn(&Option<T>[@b]) -> bool[!b])]
+    const fn is_none(&self) -> bool;
+}