Keep deserialize aliases as a sorted set

serde_derive/src/de.rs

@@ -2001,7 +2001,7 @@ fn deserialize_untagged_newtype_variant(
 }
 
 fn deserialize_generated_identifier(
-    fields: &[(&str, Ident, &[String])],
+    fields: &[(&str, Ident, &BTreeSet<String>)],
     cattrs: &attr::Container,
     is_variant: bool,
     other_idx: Option<usize>,
@@ -2187,7 +2187,7 @@ fn deserialize_custom_identifier(
 
 fn deserialize_identifier(
     this_value: &TokenStream,
-    fields: &[(&str, Ident, &[String])],
+    fields: &[(&str, Ident, &BTreeSet<String>)],
     is_variant: bool,
     fallthrough: Option<TokenStream>,
     fallthrough_borrowed: Option<TokenStream>,

serde_derive/src/internals/attr.rs

@@ -134,7 +134,7 @@ pub struct Name {
     serialize_renamed: bool,
     deserialize: String,
     deserialize_renamed: bool,
-    deserialize_aliases: Vec<String>,
+    deserialize_aliases: BTreeSet<String>,
 }
 
 fn unraw(ident: &Ident) -> String {
@@ -148,16 +148,12 @@ impl Name {
         de_name: Attr<String>,
         de_aliases: Option<VecAttr<String>>,
     ) -> Name {
-        let deserialize_aliases = match de_aliases {
-            Some(de_aliases) => {
-                let mut alias_list = BTreeSet::new();
-                for alias_name in de_aliases.get() {
-                    alias_list.insert(alias_name);
-                }
-                alias_list.into_iter().collect()
+        let mut alias_set = BTreeSet::new();
+        if let Some(de_aliases) = de_aliases {
+            for alias_name in de_aliases.get() {
+                alias_set.insert(alias_name);
             }
-            None => Vec::new(),
-        };
+        }
 
         let ser_name = ser_name.get();
         let ser_renamed = ser_name.is_some();
@@ -168,7 +164,7 @@ impl Name {
             serialize_renamed: ser_renamed,
             deserialize: de_name.unwrap_or(source_name),
             deserialize_renamed: de_renamed,
-            deserialize_aliases,
+            deserialize_aliases: alias_set,
         }
     }
 
@@ -182,23 +178,9 @@ impl Name {
         &self.deserialize
     }
 
-    fn deserialize_aliases(&self) -> &[String] {
+    fn deserialize_aliases(&self) -> &BTreeSet<String> {
         &self.deserialize_aliases
     }
-
-    fn insert_deserialize_name_into_aliases(&mut self) {
-        // `deserialize_aliases` was constructed from a BTreeSet, so it is
-        // sorted and does not contain duplicates.
-        //
-        // In `Name::from_attrs` it's too early to insert the field's real name
-        // because rename_all rules have not yet gotten applied at that point.
-        match self.deserialize_aliases.binary_search(&self.deserialize) {
-            Ok(_) => {} // already present
-            Err(pos) => self
-                .deserialize_aliases
-                .insert(pos, self.deserialize.clone()),
-        }
-    }
 }
 
 #[derive(Copy, Clone)]
@@ -986,7 +968,7 @@ impl Variant {
         &self.name
     }
 
-    pub fn aliases(&self) -> &[String] {
+    pub fn aliases(&self) -> &BTreeSet<String> {
         self.name.deserialize_aliases()
     }
 
@@ -997,7 +979,9 @@ impl Variant {
         if !self.name.deserialize_renamed {
             self.name.deserialize = rules.deserialize.apply_to_variant(&self.name.deserialize);
         }
-        self.name.insert_deserialize_name_into_aliases();
+        self.name
+            .deserialize_aliases
+            .insert(self.name.deserialize.clone());
     }
 
     pub fn rename_all_rules(&self) -> RenameAllRules {
@@ -1326,7 +1310,7 @@ impl Field {
         &self.name
     }
 
-    pub fn aliases(&self) -> &[String] {
+    pub fn aliases(&self) -> &BTreeSet<String> {
         self.name.deserialize_aliases()
     }
 
@@ -1337,7 +1321,9 @@ impl Field {
         if !self.name.deserialize_renamed {
             self.name.deserialize = rules.deserialize.apply_to_field(&self.name.deserialize);
         }
-        self.name.insert_deserialize_name_into_aliases();
+        self.name
+            .deserialize_aliases
+            .insert(self.name.deserialize.clone());
     }
 
     pub fn skip_serializing(&self) -> bool {