fix: bugs with enumeration of vars

crates/erg_common/dict.rs

@@ -205,11 +205,20 @@ impl<K: Hash + Eq, V> Dict<K, V> {
         self.dict.remove(k)
     }
 
+    /// NOTE: This method does not consider pairing with values and keys. That is, a value may be paired with a different key (can be considered equal).
+    /// If you need to consider the pairing of the keys and values, use `guaranteed_extend` instead.
     #[inline]
     pub fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iter: I) {
         self.dict.extend(iter);
     }
 
+    #[inline]
+    pub fn guaranteed_extend<I: IntoIterator<Item = (K, V)>>(&mut self, other: I) {
+        for (k, v) in other {
+            self.dict.entry(k).or_insert(v);
+        }
+    }
+
     #[inline]
     pub fn merge(&mut self, other: Self) {
         self.dict.extend(other.dict);
@@ -222,9 +231,9 @@ impl<K: Hash + Eq, V> Dict<K, V> {
     }
 
     #[inline]
-    pub fn diff(mut self, other: Self) -> Self {
-        for (k, _) in other.dict {
-            self.dict.remove(&k);
+    pub fn diff(mut self, other: &Self) -> Self {
+        for k in other.dict.keys() {
+            self.dict.remove(k);
         }
         self
     }

crates/erg_common/levenshtein.rs

@@ -40,7 +40,7 @@ pub fn levenshtein(a: &str, b: &str, limit: usize) -> Option<usize> {
     (dcol[m] <= limit).then_some(dcol[m])
 }
 
-pub fn get_similar_name<'a, S: ?Sized, I: Iterator<Item = &'a S> + Clone>(
+pub fn get_similar_name<'a, S: ?Sized, I: Iterator<Item = &'a S>>(
     candidates: I,
     name: &str,
 ) -> Option<&'a S>
@@ -58,7 +58,7 @@ where
     }
 }
 
-pub fn get_similar_name_and_some<'a, S: ?Sized, T, I: Iterator<Item = (&'a T, &'a S)> + Clone>(
+pub fn get_similar_name_and_some<'a, S: ?Sized, T, I: Iterator<Item = (&'a T, &'a S)>>(
     candidates: I,
     name: &str,
 ) -> Option<(&'a T, &'a S)>