feat: 函数 length 属性（字节码函数/bind 包装器）+ getter/setter name 前缀

crates/oxide_vm/src/dispatch/call.rs

@@ -121,6 +121,7 @@ impl Vm {
         let needs_home_object = sub.needs_home_object;
         let upvalue_captures = sub.upvalue_captures.clone();
         let function_name = sub.function_name.clone();
+        let function_length = sub.function_length;
         let result = self.create_function_object(
             sub_idx,
             is_arrow,
@@ -130,13 +131,18 @@ impl Vm {
         );
         // 函数名推断：emit 端在变量声明/对象属性赋值点设置 function_name。
         let func_obj = unsafe { &mut *result.as_js_object_ptr() };
+        let length_si = self.kernel_core.perm_interner().intern("length").0;
         let name_si = self.kernel_core.perm_interner().intern("name").0;
+        // length/name 描述符均为不可写、不可枚举、可配置（SetFunctionLength /
+        // SetFunctionName 语义）；length 先于 name 定义保证属性序 [prototype, length, name]。
+        let attrs = PropAttributes::new(false, false, true);
+        let length_val = JsValue::int(function_length as i32);
+        self.define_data_property(func_obj, length_si, length_val, attrs)?;
         let name_val = function_name
             .as_deref()
             .map(|n| self.new_string(n))
             .unwrap_or_else(|| self.new_string(""));
-        // name 属性描述符：不可写、不可枚举、可配置（SetFunctionName 语义）。
-        self.define_data_property(func_obj, name_si, name_val, PropAttributes::new(false, false, true))?;
+        self.define_data_property(func_obj, name_si, name_val, attrs)?;
         if !upvalue_captures.is_empty() {
             // 链式捕获（parent_uv_idx）：从父闭包（创建者）的 upvalues 取 cell。
             let parent_upvalues: Vec<*mut Cell> = match self.current_callee() {

crates/oxide_vm/src/vm_props.rs

@@ -237,9 +237,16 @@ impl Vm {
         &mut self, setter: JsValue, receiver: JsValue, val: JsValue, use_frame_push: bool,
     ) -> Result<(), String> {
         vm_trace!("call_or_push_setter: frame_push={}", use_frame_push);
+        // native setter 抛错经 call_function_sync 以 String 返回（未 unwind）——
+        // 在此经 raise_call_error 恢复为可捕获的 JS 异常（与 getter 路径对称）。
+        let call_native = |vm: &mut Self| -> Result<(), String> {
+            if let Err(err) = vm.call_function_sync(setter, receiver, &[val]) {
+                vm.raise_call_error(&err)?;
+            }
+            Ok(())
+        };
         if !use_frame_push {
-            self.call_function_sync(setter, receiver, &[val])?;
-            return Ok(());
+            return call_native(self);
         }
         if !setter.is_object() {
             return self.raise_type_error("setter is not callable");
@@ -249,8 +256,7 @@ impl Vm {
             return self.raise_type_error("setter is not callable");
         }
         if setter_obj.native_fn().is_some() {
-            self.call_function_sync(setter, receiver, &[val])?;
-            return Ok(());
+            return call_native(self);
         }
         self.push_bytecode_frame(
             setter,

crates/oxide_vm/tests/function_length_tests.rs

@@ -0,0 +1,126 @@
+//! 函数 length/name 属性集成测试：普通字节码函数、箭头函数、bind 包装器、
+//! getter/setter 前缀。每个用例独立编译执行，断言顶层表达式结果。
+
+use oxide_bytecode::module::CompiledModule;
+use oxide_compiler::compiler::Compiler;
+use oxide_parser::Allocator;
+use oxide_types::value::JsValue;
+use oxide_vm::vm::Vm;
+
+fn eval(source: &str) -> JsValue {
+    let allocator = Allocator::default();
+    let program = oxide_parser::parse(&allocator, source).expect("parse failed");
+    let module = Compiler::new().compile(&program).expect("compile failed");
+    run(&module)
+}
+
+fn run(module: &CompiledModule) -> JsValue {
+    let mut vm = Vm::new();
+    vm.run(module).expect("vm run failed")
+}
+
+fn eval_str(source: &str) -> String {
+    let v = eval(source);
+    if v.is_string() {
+        unsafe { oxide_runtime_api::string_data(v) }.to_string()
+    } else {
+        format!("{v}")
+    }
+}
+
+#[test]
+fn bytecode_function_length_counts_formals_before_first_default() {
+    assert_eq!(eval("function f(a,b,c){}; f.length"), JsValue::int(3));
+    assert_eq!(eval("function f(a,b=1,c){}; f.length"), JsValue::int(1));
+    assert_eq!(eval("function f(...r){}; f.length"), JsValue::int(0));
+    assert_eq!(eval("var f = function named(a,b,c){}; f.length"), JsValue::int(3));
+}
+
+#[test]
+fn arrow_function_length_matches_formals() {
+    assert_eq!(eval("var f=(a,b)=>a+b; f.length"), JsValue::int(2));
+    assert_eq!(eval("var f=(a,b,c)=>a+b+c; f.length"), JsValue::int(3));
+}
+
+#[test]
+fn class_method_and_accessor_names() {
+    assert_eq!(eval("class C { m(a,b){} }; C.prototype.m.length"), JsValue::int(2));
+    assert_eq!(
+        eval_str("class C { get x(){} set x(v){} }; Object.getOwnPropertyDescriptor(C.prototype,'x').get.name"),
+        "get x"
+    );
+    assert_eq!(
+        eval_str("class C { get x(){} set x(v){} }; Object.getOwnPropertyDescriptor(C.prototype,'x').set.name"),
+        "set x"
+    );
+}
+
+#[test]
+fn object_literal_accessor_names() {
+    assert_eq!(
+        eval_str("var o={ get x(){}, set x(v){} }; Object.getOwnPropertyDescriptor(o,'x').get.name"),
+        "get x"
+    );
+    assert_eq!(
+        eval_str("var o={ get x(){}, set x(v){} }; Object.getOwnPropertyDescriptor(o,'x').set.name"),
+        "set x"
+    );
+}
+
+#[test]
+fn bind_wrapper_length_is_target_length_minus_bound_args() {
+    assert_eq!(eval("function f(a,b){}; f.bind(null,1).length"), JsValue::int(1));
+    assert_eq!(eval("function f(){}; f.bind(null,1,2,3).length"), JsValue::int(0));
+    assert_eq!(eval("function f(a,b,c){}; f.bind(null).length"), JsValue::int(3));
+}
+
+#[test]
+fn bind_wrapper_name_has_bound_prefix() {
+    assert_eq!(eval_str("function f(a){}; f.bind(null).name"), "bound f");
+    assert_eq!(eval_str("(function(){}).bind(null).name"), "bound ");
+}
+
+#[test]
+fn bind_wrapper_length_supports_infinity_and_large_values() {
+    assert_eq!(
+        eval("function f(){}; Object.defineProperty(f,'length',{value:Infinity}); f.bind().length === Infinity"),
+        JsValue::bool(true)
+    );
+    assert_eq!(
+        eval("function f(){}; Object.defineProperty(f,'length',{value:2147483648}); f.bind().length"),
+        JsValue::float(2147483648.0)
+    );
+}
+
+#[test]
+fn bind_wrapper_caller_and_arguments_are_poisoned() {
+    assert_eq!(
+        eval_str("var b=(function(){}).bind({}); try { b.caller; 'no' } catch(e) { e instanceof TypeError ? 'throws' : 'wrong' }"),
+        "throws"
+    );
+    assert_eq!(
+        eval_str("var b=(function(){}).bind({}); try { b.caller = 1; 'no' } catch(e) { e instanceof TypeError ? 'throws' : 'wrong' }"),
+        "throws"
+    );
+}
+
+#[test]
+fn length_and_name_descriptors_are_non_writable_non_enumerable_configurable() {
+    assert_eq!(
+        eval_str("function f(){}; var d=Object.getOwnPropertyDescriptor(f,'length'); d.writable===false && d.enumerable===false && d.configurable===true"),
+        "true"
+    );
+}
+
+#[test]
+fn length_comes_before_name_in_property_order() {
+    assert_eq!(
+        eval_str("function f(a,b,c){}; var p=Object.getOwnPropertyNames(f); p[p.indexOf('length')] < p[p.indexOf('name')]"),
+        "true"
+    );
+}
+
+#[test]
+fn anonymous_function_name_is_empty_string() {
+    assert_eq!(eval_str("(function(){}).name"), "");
+}