fix: var 捕获绑定函数与程序入口统一初始化为 undefined 消除 TDZ 误报

crates/oxide_emit/src/closure.rs

@@ -7,7 +7,7 @@
 use std::collections::{BTreeMap, HashSet};
 
 use oxide_bytecode::module::UpvalueCapture;
-use oxide_parser::{ClassBody, ClassElement, Expression, Statement};
+use oxide_parser::{ClassBody, ClassElement, Expression, Statement, VariableDeclarationKind};
 
 use crate::Emitter;
 
@@ -63,6 +63,85 @@ impl Emitter {
         }
     }
 
+    /// 收集语句树中全部 `var` 声明名（var 提升到函数/程序作用域，递归进嵌套块）。
+    /// 供函数/程序入口批量 MAKE_CELL(undefined) 使用（var 入口实例化语义）。
+    pub(crate) fn collect_var_binding_names(&self, stmts: &[Statement]) -> HashSet<String> {
+        let mut names = HashSet::new();
+        self.collect_var_names_stmt(stmts, &mut names);
+        names
+    }
+
+    fn collect_var_names_stmt(&self, stmts: &[Statement], out: &mut HashSet<String>) {
+        for stmt in stmts {
+            match stmt {
+                Statement::VariableDeclaration(vd) => {
+                    if matches!(vd.kind, VariableDeclarationKind::Var) {
+                        for d in &vd.declarations {
+                            self.collect_binding_pattern_names(&d.id, out);
+                        }
+                    }
+                }
+                Statement::BlockStatement(b) => self.collect_var_names_stmt(&b.body, out),
+                Statement::IfStatement(is) => {
+                    self.collect_var_names_stmt(std::slice::from_ref(&is.consequent), out);
+                    if let Some(alt) = &is.alternate {
+                        self.collect_var_names_stmt(std::slice::from_ref(alt), out);
+                    }
+                }
+                Statement::WhileStatement(w) => self.collect_var_names_stmt(std::slice::from_ref(&w.body), out),
+                Statement::DoWhileStatement(d) => self.collect_var_names_stmt(std::slice::from_ref(&d.body), out),
+                Statement::ForStatement(f) => {
+                    if let Some(oxide_parser::ForStatementInit::VariableDeclaration(vd)) = &f.init {
+                        if matches!(vd.kind, VariableDeclarationKind::Var) {
+                            for d in &vd.declarations {
+                                self.collect_binding_pattern_names(&d.id, out);
+                            }
+                        }
+                    }
+                    self.collect_var_names_stmt(std::slice::from_ref(&f.body), out);
+                }
+                Statement::ForInStatement(fi) => {
+                    if let oxide_parser::ForStatementLeft::VariableDeclaration(_) = &fi.left {
+                        self.collect_for_left_decl_names(&fi.left, out);
+                    }
+                    self.collect_var_names_stmt(std::slice::from_ref(&fi.body), out);
+                }
+                Statement::ForOfStatement(fo) => {
+                    if let oxide_parser::ForStatementLeft::VariableDeclaration(_) = &fo.left {
+                        self.collect_for_left_decl_names(&fo.left, out);
+                    }
+                    self.collect_var_names_stmt(std::slice::from_ref(&fo.body), out);
+                }
+                Statement::SwitchStatement(sw) => {
+                    for case in &sw.cases {
+                        self.collect_var_names_stmt(&case.consequent, out);
+                    }
+                }
+                Statement::TryStatement(ts) => {
+                    self.collect_var_names_stmt(&ts.block.body, out);
+                    if let Some(h) = &ts.handler {
+                        self.collect_var_names_stmt(&h.body.body, out);
+                    }
+                    if let Some(f) = &ts.finalizer {
+                        self.collect_var_names_stmt(&f.body, out);
+                    }
+                }
+                Statement::LabeledStatement(ls) => self.collect_var_names_stmt(std::slice::from_ref(&ls.body), out),
+                Statement::WithStatement(ws) => self.collect_var_names_stmt(std::slice::from_ref(&ws.body), out),
+                Statement::ExportNamedDeclaration(exp) => {
+                    if let Some(oxide_parser::Declaration::VariableDeclaration(vd)) = &exp.declaration {
+                        if matches!(vd.kind, VariableDeclarationKind::Var) {
+                            for d in &vd.declarations {
+                                self.collect_binding_pattern_names(&d.id, out);
+                            }
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
     /// 收集当前函数作用域声明的绑定名（参数 + 变量/函数声明，含嵌套 block，不含嵌套函数体）。
     pub(crate) fn collect_own_binding_names(&self, param_names: &[&str], stmts: &[Statement]) -> HashSet<String> {
         let mut names = HashSet::new();

crates/oxide_emit/src/emit.rs

@@ -1329,6 +1329,31 @@ impl Emitter {
             ));
         }
 
+        // var 绑定函数入口实例化：被捕获的 var 名统一 MAKE_CELL(undefined)。
+        // 规范上 var 在函数入口即初始化为 undefined（HoistDeclaration），声明语句
+        // 只是赋值；否则声明语句前创建的闭包读取占位 cell → TDZ 误报。参数与
+        // arguments 已在上方初始化（跳过以免覆盖参数值）；let/const/class 保持
+        // TDZ 语义不动。声明语句的 MAKE_CELL 按占位更新语义覆盖此初值。
+        let var_names: Vec<String> = self
+            .collect_var_binding_names(body_stmts)
+            .into_iter()
+            .filter(|n| !param_names.contains(&n.as_str()) && n != "arguments")
+            .filter(|n| ctx.captured_bindings.contains_key(n))
+            .collect();
+        if !var_names.is_empty() {
+            let undef_reg = self.emit_undefined(ctx);
+            for name in var_names {
+                if let Some(&cell_idx) = ctx.captured_bindings.get(&name) {
+                    ctx.inst(Inst::new(
+                        OpCode::MAKE_CELL,
+                        Operand::Reg(undef_reg),
+                        Operand::Imm(cell_idx as u16),
+                        Operand::None,
+                    ));
+                }
+            }
+        }
+
         Ok(param_base)
     }
 
@@ -1459,6 +1484,28 @@ impl Emitter {
         ctx.own_bindings = self.collect_own_binding_names(&[], &program.body);
         ctx.captured_bindings = self.collect_captured_bindings(&program.body, &[], &ctx.own_bindings);
 
+        // 顶层 var 入口实例化：被捕获的 var 名统一 MAKE_CELL(undefined)，使 var
+        // 声明语句执行前创建的闭包读取到 undefined（脚本 GlobalDeclarationInstantiation
+        // 语义），而非占位 cell 的 TDZ 误报。声明语句的 MAKE_CELL 覆盖此初值。
+        let var_names: Vec<String> = self
+            .collect_var_binding_names(&program.body)
+            .into_iter()
+            .filter(|n| ctx.captured_bindings.contains_key(n))
+            .collect();
+        if !var_names.is_empty() {
+            let undef_reg = self.emit_undefined(&mut ctx);
+            for name in var_names {
+                if let Some(&cell_idx) = ctx.captured_bindings.get(&name) {
+                    ctx.inst(Inst::new(
+                        OpCode::MAKE_CELL,
+                        Operand::Reg(undef_reg),
+                        Operand::Imm(cell_idx as u16),
+                        Operand::None,
+                    ));
+                }
+            }
+        }
+
         // 首个 sub-pass：发函数声明（hoisting），保证任何代码运行前函数对象已就绪。
         for stmt in &program.body {
             if matches!(stmt, Statement::FunctionDeclaration(_)) {