From e47bd59a4fece1e4607cb096256c79d10134b937 Mon Sep 17 00:00:00 2001
From: HalidOdat <halidodat@gmail.com>
Date: Mon, 3 May 2021 22:35:48 +0200
Subject: [PATCH] Use Box<str> instead of String in Environment

---
 boa/src/environment/declarative_environment_record.rs | 10 +++++-----
 boa/src/environment/global_environment_record.rs      |  6 +++---
 boa/src/environment/lexical_environment.rs            | 11 +----------
 3 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/boa/src/environment/declarative_environment_record.rs b/boa/src/environment/declarative_environment_record.rs
index e809baf4431..6ca3c3918ff 100644
--- a/boa/src/environment/declarative_environment_record.rs
+++ b/boa/src/environment/declarative_environment_record.rs
@@ -34,7 +34,7 @@ pub struct DeclarativeEnvironmentRecordBinding {
 /// declarations contained within its scope.
 #[derive(Debug, Trace, Finalize, Clone)]
 pub struct DeclarativeEnvironmentRecord {
-    pub env_rec: FxHashMap<String, DeclarativeEnvironmentRecordBinding>,
+    pub env_rec: FxHashMap<Box<str>, DeclarativeEnvironmentRecordBinding>,
     pub outer_env: Option<Environment>,
 }
 
@@ -65,14 +65,14 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
     ) -> Result<()> {
         if !allow_name_reuse {
             assert!(
-                !self.env_rec.contains_key(&name),
+                !self.env_rec.contains_key(name.as_str()),
                 "Identifier {} has already been declared",
                 name
             );
         }
 
         self.env_rec.insert(
-            name,
+            name.into_boxed_str(),
             DeclarativeEnvironmentRecordBinding {
                 value: None,
                 can_delete: deletion,
@@ -90,13 +90,13 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         _context: &mut Context,
     ) -> Result<()> {
         assert!(
-            !self.env_rec.contains_key(&name),
+            !self.env_rec.contains_key(name.as_str()),
             "Identifier {} has already been declared",
             name
         );
 
         self.env_rec.insert(
-            name,
+            name.into_boxed_str(),
             DeclarativeEnvironmentRecordBinding {
                 value: None,
                 can_delete: true,
diff --git a/boa/src/environment/global_environment_record.rs b/boa/src/environment/global_environment_record.rs
index c8de613bc46..2c6c83baf72 100644
--- a/boa/src/environment/global_environment_record.rs
+++ b/boa/src/environment/global_environment_record.rs
@@ -27,7 +27,7 @@ pub struct GlobalEnvironmentRecord {
     pub object_record: ObjectEnvironmentRecord,
     pub global_this_binding: GcObject,
     pub declarative_record: DeclarativeEnvironmentRecord,
-    pub var_names: FxHashSet<String>,
+    pub var_names: FxHashSet<Box<str>>,
 }
 
 impl GlobalEnvironmentRecord {
@@ -119,8 +119,8 @@ impl GlobalEnvironmentRecord {
         }
 
         let var_declared_names = &mut self.var_names;
-        if !var_declared_names.contains(&name) {
-            var_declared_names.insert(name);
+        if !var_declared_names.contains(name.as_str()) {
+            var_declared_names.insert(name.into_boxed_str());
         }
         Ok(())
     }
diff --git a/boa/src/environment/lexical_environment.rs b/boa/src/environment/lexical_environment.rs
index 3e27ad44fc0..fdf4b8a97bc 100644
--- a/boa/src/environment/lexical_environment.rs
+++ b/boa/src/environment/lexical_environment.rs
@@ -60,16 +60,7 @@ impl fmt::Display for EnvironmentError {
     }
 }
 
-impl error::Error for EnvironmentError {
-    fn description(&self) -> &str {
-        &self.details
-    }
-
-    fn cause(&self) -> Option<&dyn error::Error> {
-        // Generic error, underlying cause isn't tracked.
-        None
-    }
-}
+impl error::Error for EnvironmentError {}
 
 impl LexicalEnvironment {
     pub fn new(global: GcObject) -> Self {