From fa67988ab41864ea076c2c4985ad1348319a913a Mon Sep 17 00:00:00 2001
From: pjh456 <147148383@qq.com>
Date: Mon, 14 Sep 2026 20:15:08 +0000
Subject: [PATCH] =?UTF-8?q?fix:=20=E5=8F=98=E9=87=8F=E5=A3=B0=E6=98=8E?=
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---
 crates/oxide_emit/src/emit.rs                 | 7 ++++---
 crates/oxide_emit/src/stmt/declaration/var.rs | 6 ++----
 crates/oxide_vm/tests/var_binding_tests.rs    | 3 ++-
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/crates/oxide_emit/src/emit.rs b/crates/oxide_emit/src/emit.rs
index 9e96fa41..07b4111d 100644
--- a/crates/oxide_emit/src/emit.rs
+++ b/crates/oxide_emit/src/emit.rs
@@ -1874,9 +1874,10 @@ impl Emitter {
             if matches!(stmt, Statement::FunctionDeclaration(_)) {
                 continue; // Already emitted above
             }
-            match self.emit_statement(stmt, &mut ctx)? {
-                Some(r) => last_result = Some(r),
-                None => last_result = None,
+            // 空完成值语句（变量/函数等声明）不覆写此前结果：保留最后一个非空
+            // 完成值，与函数体 emit_body_stmts 的收敛口径一致。
+            if let Some(r) = self.emit_statement(stmt, &mut ctx)? {
+                last_result = Some(r);
             }
         }
         if let Some(r) = last_result {
diff --git a/crates/oxide_emit/src/stmt/declaration/var.rs b/crates/oxide_emit/src/stmt/declaration/var.rs
index a170ba33..5acd452e 100644
--- a/crates/oxide_emit/src/stmt/declaration/var.rs
+++ b/crates/oxide_emit/src/stmt/declaration/var.rs
@@ -18,10 +18,10 @@ impl Emitter {
     }
 
     /// 变量声明本体：供 export 声明复用（导出声明需先按普通声明 emit，再就地注册导出值）。
+    /// 变量声明语句完成值按规范为空记录（对外 undefined），不回填结果寄存器。
     pub(crate) fn emit_variable_declaration(
         &self, decl: &VariableDeclaration, ctx: &mut CompileCtx,
     ) -> Result<Option<u32>, String> {
-        let mut r = None;
         for d in &decl.declarations {
             let is_const = matches!(decl.kind, VariableDeclarationKind::Const);
             if is_const && d.init.is_none() {
@@ -39,7 +39,6 @@ impl Emitter {
                         }
                     }
                 }
-                r = Some(val_reg);
             } else {
                 let BindingPattern::BindingIdentifier(bi) = &d.id else {
                     return Err("destructuring declaration requires an initializer".into());
@@ -82,9 +81,8 @@ impl Emitter {
                     ctx.inst(Inst::new(OpCode::STORE_VAR, Operand::Reg(target_reg), Operand::Reg(tmp), Operand::None));
                 }
                 ctx.init_var(bi.name.as_str());
-                r = Some(var_reg);
             }
         }
-        Ok(r)
+        Ok(None)
     }
 }
diff --git a/crates/oxide_vm/tests/var_binding_tests.rs b/crates/oxide_vm/tests/var_binding_tests.rs
index af791df9..99d674f6 100644
--- a/crates/oxide_vm/tests/var_binding_tests.rs
+++ b/crates/oxide_vm/tests/var_binding_tests.rs
@@ -23,7 +23,8 @@ fn eval(source: &str) -> String {
 
 #[test]
 fn eval_var_declaration() {
-    assert_eq!(eval("var x = 42"), "42");
+    // 变量声明语句完成值按规范为空记录（对外 undefined），不回填初始化器值。
+    assert_eq!(eval("var x = 42"), "undefined");
 }
 
 #[test]