Locatable selectors

1 files changed, 12 insertions, 4 deletions

diff --git a/src/eval/cast.rs b/src/eval/cast.rs
index 7b507dbb..92e4212f 100644
--- a/src/eval/cast.rs
+++ b/src/eval/cast.rs
@@ -237,7 +237,7 @@ impl<T> Variadics for Vec<T> {
 }
 
 /// Describes a possible value for a cast.
-#[derive(Debug, Clone, Hash)]
+#[derive(Debug, Clone, Hash, PartialEq, PartialOrd)]
 pub enum CastInfo {
     /// Any value is okay.
     Any,
@@ -302,15 +302,23 @@ impl Add for CastInfo {
     fn add(self, rhs: Self) -> Self {
         Self::Union(match (self, rhs) {
             (Self::Union(mut lhs), Self::Union(rhs)) => {
-                lhs.extend(rhs);
+                for cast in rhs {
+                    if !lhs.contains(&cast) {
+                        lhs.push(cast);
+                    }
+                }
                 lhs
             }
             (Self::Union(mut lhs), rhs) => {
-                lhs.push(rhs);
+                if !lhs.contains(&rhs) {
+                    lhs.push(rhs);
+                }
                 lhs
             }
             (lhs, Self::Union(mut rhs)) => {
-                rhs.insert(0, lhs);
+                if !rhs.contains(&lhs) {
+                    rhs.insert(0, lhs);
+                }
                 rhs
             }
             (lhs, rhs) => vec![lhs, rhs],