Remove unnecessary 'DerefMut' impl from 'Local<T>' (#406)

Local handles never need to be mutable. This patch also rounds up the
last few places where we were still asking the user to pass an `&mut T`
to an API method.

src/function.rs

@@ -90,7 +90,7 @@ impl<'cb> ReturnValue<'cb> {
   /// Getter. Creates a new Local<> so it comes with a certain performance
   /// hit. If the ReturnValue was not yet set, this will return the undefined
   /// value.
-  pub fn get<'s>(&mut self, scope: &mut HandleScope<'s>) -> Local<'s, Value> {
+  pub fn get<'s>(&self, scope: &mut HandleScope<'s>) -> Local<'s, Value> {
     unsafe { scope.cast_local(|_| v8__ReturnValue__Get(self)) }.unwrap()
   }
 }

src/local.rs

@@ -1,7 +1,6 @@
 use std::marker::PhantomData;
 use std::mem::transmute;
 use std::ops::Deref;
-use std::ops::DerefMut;
 use std::ptr::NonNull;
 
 /// An object reference managed by the v8 garbage collector.
@@ -82,12 +81,6 @@ impl<'s, T> Deref for Local<'s, T> {
   }
 }
 
-impl<'s, T> DerefMut for Local<'s, T> {
-  fn deref_mut(&mut self) -> &mut T {
-    unsafe { self.0.as_mut() }
-  }
-}
-
 #[test]
 fn test_size_of_local() {
   use crate::Value;

src/module.rs

@@ -204,7 +204,7 @@ impl Module {
   /// exception is propagated.)
   #[must_use]
   pub fn instantiate_module<'a>(
-    &mut self,
+    &self,
     scope: &mut HandleScope,
     callback: impl MapFnTo<ResolveCallback<'a>>,
   ) -> Option<bool> {

src/object.rs

@@ -250,7 +250,7 @@ impl Object {
 
   /// Note: SideEffectType affects the getter only, not the setter.
   pub fn set_accessor(
-    &mut self,
+    &self,
     scope: &mut HandleScope,
     name: Local<Name>,
     getter: impl for<'s> MapFnTo<AccessorNameGetterCallback<'s>>,

src/proxy.rs

@@ -31,24 +31,24 @@ impl Proxy {
   }
 
   pub fn get_handler<'s>(
-    &mut self,
+    &self,
     scope: &mut HandleScope<'s>,
   ) -> Local<'s, Value> {
     unsafe { scope.cast_local(|_| v8__Proxy__GetHandler(&*self)) }.unwrap()
   }
 
   pub fn get_target<'s>(
-    &mut self,
+    &self,
     scope: &mut HandleScope<'s>,
   ) -> Local<'s, Value> {
     unsafe { scope.cast_local(|_| v8__Proxy__GetTarget(&*self)) }.unwrap()
   }
 
-  pub fn is_revoked(&mut self) -> bool {
+  pub fn is_revoked(&self) -> bool {
     unsafe { v8__Proxy__IsRevoked(self) }
   }
 
-  pub fn revoke(&mut self) {
+  pub fn revoke(&self) {
     unsafe { v8__Proxy__Revoke(self) };
   }
 }

src/script.rs

@@ -62,7 +62,7 @@ impl Script {
   /// context in which it was created (ScriptCompiler::CompileBound or
   /// UnboundScript::BindToCurrentContext()).
   pub fn run<'s>(
-    &mut self,
+    &self,
     scope: &mut HandleScope<'s>,
   ) -> Option<Local<'s, Value>> {
     unsafe {

src/template.rs

@@ -80,12 +80,12 @@ impl FunctionTemplate {
 
   /// Returns the unique function instance in the current execution context.
   pub fn get_function<'s>(
-    &mut self,
+    &self,
     scope: &mut HandleScope<'s>,
   ) -> Option<Local<'s, Function>> {
     unsafe {
       scope.cast_local(|sd| {
-        v8__FunctionTemplate__GetFunction(&*self, sd.get_current_context())
+        v8__FunctionTemplate__GetFunction(self, sd.get_current_context())
       })
     }
   }
@@ -93,8 +93,8 @@ impl FunctionTemplate {
   /// Set the class name of the FunctionTemplate. This is used for
   /// printing objects created with the function created from the
   /// FunctionTemplate as its constructor.
-  pub fn set_class_name(&mut self, name: Local<String>) {
+  pub fn set_class_name(&self, name: Local<String>) {
-    unsafe { v8__FunctionTemplate__SetClassName(&*self, &*name) };
+    unsafe { v8__FunctionTemplate__SetClassName(self, &*name) };
   }
 }
 

tests/slots.rs

@@ -43,7 +43,7 @@ impl CoreIsolate {
     let context = v8::Context::new(scope);
     let scope = &mut v8::ContextScope::new(scope, context);
     let source = v8::String::new(scope, code).unwrap();
-    let mut script = v8::Script::compile(scope, source, None).unwrap();
+    let script = v8::Script::compile(scope, source, None).unwrap();
     let r = script.run(scope);
     r.is_some()
   }

tests/test_api.rs

@@ -529,7 +529,7 @@ fn eval<'s>(
 ) -> Option<v8::Local<'s, v8::Value>> {
   let scope = &mut v8::EscapableHandleScope::new(scope);
   let source = v8::String::new(scope, code).unwrap();
-  let mut script = v8::Script::compile(scope, source, None).unwrap();
+  let script = v8::Script::compile(scope, source, None).unwrap();
   let r = script.run(scope);
   r.map(|v| scope.escape(v))
 }
@@ -689,7 +689,7 @@ fn terminate_execution() {
   // Rn an infinite loop, which should be terminated.
   let source = v8::String::new(scope, "for(;;) {}").unwrap();
   let r = v8::Script::compile(scope, source, None);
-  let mut script = r.unwrap();
+  let script = r.unwrap();
   let result = script.run(scope);
   assert!(result.is_none());
   // TODO assert_eq!(e.to_string(), "Uncaught Error: execution terminated")
@@ -774,7 +774,7 @@ fn add_message_listener() {
     let context = v8::Context::new(scope);
     let scope = &mut v8::ContextScope::new(scope, context);
     let source = v8::String::new(scope, "throw 'foo'").unwrap();
-    let mut script = v8::Script::compile(scope, source, None).unwrap();
+    let script = v8::Script::compile(scope, source, None).unwrap();
     assert!(script.run(scope).is_none());
     assert_eq!(CALL_COUNT.load(Ordering::SeqCst), 1);
   }
@@ -814,8 +814,7 @@ fn set_host_initialize_import_meta_object_callback() {
     let context = v8::Context::new(scope);
     let scope = &mut v8::ContextScope::new(scope, context);
     let source = mock_source(scope, "google.com", "import.meta;");
-    let mut module =
+    let module = v8::script_compiler::compile_module(scope, source).unwrap();
-      v8::script_compiler::compile_module(scope, source).unwrap();
     let result =
       module.instantiate_module(scope, unexpected_module_resolve_callback);
     assert!(result.is_some());
@@ -839,7 +838,7 @@ fn script_compile_and_run() {
     let context = v8::Context::new(scope);
     let scope = &mut v8::ContextScope::new(scope, context);
     let source = v8::String::new(scope, "'Hello ' + 13 + 'th planet'").unwrap();
-    let mut script = v8::Script::compile(scope, source, None).unwrap();
+    let script = v8::Script::compile(scope, source, None).unwrap();
     source.to_rust_string_lossy(scope);
     let result = script.run(scope).unwrap();
     let result = result.to_string(scope).unwrap();
@@ -880,7 +879,7 @@ fn script_origin() {
     );
 
     let source = v8::String::new(scope, "1+2").unwrap();
-    let mut script =
+    let script =
       v8::Script::compile(scope, source, Some(&script_origin)).unwrap();
     source.to_rust_string_lossy(scope);
     let _result = script.run(scope).unwrap();
@@ -1090,8 +1089,7 @@ fn object_template_from_function_template() {
   let isolate = &mut v8::Isolate::new(Default::default());
   {
     let scope = &mut v8::HandleScope::new(isolate);
-    let mut function_templ =
+    let function_templ = v8::FunctionTemplate::new(scope, fortytwo_callback);
-      v8::FunctionTemplate::new(scope, fortytwo_callback);
     let expected_class_name = v8::String::new(scope, "fortytwo").unwrap();
     function_templ.set_class_name(expected_class_name);
     let object_templ =
@@ -1240,7 +1238,7 @@ fn object_set_accessor() {
       CALL_COUNT.fetch_add(1, Ordering::SeqCst);
     };
 
-    let mut obj = v8::Object::new(scope);
+    let obj = v8::Object::new(scope);
 
     let getter_key = v8::String::new(scope, "getter_key").unwrap();
     obj.set_accessor(scope, getter_key.into(), getter);
@@ -1334,7 +1332,7 @@ fn proxy() {
     let handler = v8::Object::new(scope);
     let maybe_proxy = v8::Proxy::new(scope, target, handler);
     assert!(maybe_proxy.is_some());
-    let mut proxy = maybe_proxy.unwrap();
+    let proxy = maybe_proxy.unwrap();
     assert!(target == proxy.get_target(scope));
     assert!(handler == proxy.get_handler(scope));
     assert!(!proxy.is_revoked());
@@ -1406,7 +1404,7 @@ fn function() {
     let global = context.global(scope);
     let recv: v8::Local<v8::Value> = global.into();
     // create function using template
-    let mut fn_template = v8::FunctionTemplate::new(scope, fn_callback);
+    let fn_template = v8::FunctionTemplate::new(scope, fn_callback);
     let function = fn_template
       .get_function(scope)
       .expect("Unable to create function");
@@ -1547,8 +1545,7 @@ fn module_instantiation_failures1() {
     let origin = mock_script_origin(scope, "foo.js");
     let source = v8::script_compiler::Source::new(source_text, &origin);
 
-    let mut module =
+    let module = v8::script_compiler::compile_module(scope, source).unwrap();
-      v8::script_compiler::compile_module(scope, source).unwrap();
     assert_eq!(v8::ModuleStatus::Uninstantiated, module.get_status());
     assert_eq!(2, module.get_module_requests_length());
 
@@ -1624,8 +1621,7 @@ fn module_evaluation() {
     let origin = mock_script_origin(scope, "foo.js");
     let source = v8::script_compiler::Source::new(source_text, &origin);
 
-    let mut module =
+    let module = v8::script_compiler::compile_module(scope, source).unwrap();
-      v8::script_compiler::compile_module(scope, source).unwrap();
     assert_eq!(v8::ModuleStatus::Uninstantiated, module.get_status());
 
     let result = module
@@ -1710,7 +1706,7 @@ fn array_buffer_view() {
     let scope = &mut v8::ContextScope::new(scope, context);
     let source =
       v8::String::new(scope, "new Uint8Array([23,23,23,23])").unwrap();
-    let mut script = v8::Script::compile(scope, source, None).unwrap();
+    let script = v8::Script::compile(scope, source, None).unwrap();
     source.to_rust_string_lossy(scope);
     let result: v8::Local<v8::ArrayBufferView> =
       script.run(scope).unwrap().try_into().unwrap();
@@ -1746,7 +1742,7 @@ fn snapshot_creator() {
       let scope = &mut v8::ContextScope::new(scope, context);
 
       let source = v8::String::new(scope, "a = 1 + 2").unwrap();
-      let mut script = v8::Script::compile(scope, source, None).unwrap();
+      let script = v8::Script::compile(scope, source, None).unwrap();
       script.run(scope).unwrap();
 
       snapshot_creator.set_default_context(context);
@@ -1767,7 +1763,7 @@ fn snapshot_creator() {
       let context = v8::Context::new(scope);
       let scope = &mut v8::ContextScope::new(scope, context);
       let source = v8::String::new(scope, "a === 3").unwrap();
-      let mut script = v8::Script::compile(scope, source, None).unwrap();
+      let script = v8::Script::compile(scope, source, None).unwrap();
       let result = script.run(scope).unwrap();
       let true_val = v8::Boolean::new(scope, true).into();
       assert!(result.same_value(true_val));
@@ -1799,7 +1795,7 @@ fn external_references() {
       let scope = &mut v8::ContextScope::new(scope, context);
 
       // create function using template
-      let mut fn_template = v8::FunctionTemplate::new(scope, fn_callback);
+      let fn_template = v8::FunctionTemplate::new(scope, fn_callback);
       let function = fn_template
         .get_function(scope)
         .expect("Unable to create function");
@@ -1863,7 +1859,7 @@ fn uint8_array() {
     let scope = &mut v8::ContextScope::new(scope, context);
     let source =
       v8::String::new(scope, "new Uint8Array([23,23,23,23])").unwrap();
-    let mut script = v8::Script::compile(scope, source, None).unwrap();
+    let script = v8::Script::compile(scope, source, None).unwrap();
     source.to_rust_string_lossy(scope);
     let result: v8::Local<v8::ArrayBufferView> =
       script.run(scope).unwrap().try_into().unwrap();
@@ -1949,7 +1945,7 @@ fn shared_array_buffer() {
         sharedBytes[5] + sharedBytes[12]",
     )
     .unwrap();
-    let mut script = v8::Script::compile(scope, source, None).unwrap();
+    let script = v8::Script::compile(scope, source, None).unwrap();
 
     let result: v8::Local<v8::Integer> =
       script.run(scope).unwrap().try_into().unwrap();
@@ -2897,8 +2893,7 @@ fn module_snapshot() {
       let origin = mock_script_origin(scope, "foo.js");
       let source = v8::script_compiler::Source::new(source_text, &origin);
 
-      let mut module =
+      let module = v8::script_compiler::compile_module(scope, source).unwrap();
-        v8::script_compiler::compile_module(scope, source).unwrap();
       assert_eq!(v8::ModuleStatus::Uninstantiated, module.get_status());
 
       let result = module.instantiate_module(
@@ -2931,12 +2926,12 @@ fn module_snapshot() {
       let true_val = v8::Boolean::new(scope, true).into();
 
       let source = v8::String::new(scope, "a === 3").unwrap();
-      let mut script = v8::Script::compile(scope, source, None).unwrap();
+      let script = v8::Script::compile(scope, source, None).unwrap();
       let result = script.run(scope).unwrap();
       assert!(result.same_value(true_val));
 
       let source = v8::String::new(scope, "b === 42").unwrap();
-      let mut script = v8::Script::compile(scope, source, None).unwrap();
+      let script = v8::Script::compile(scope, source, None).unwrap();
       let result = script.run(scope).unwrap();
       assert!(result.same_value(true_val));
     }