feat(joinir): S-5.2-improved - VM完全意味論統合完了

Phase 27-shortterm S-5.2-improved 実装完了:

## 実装内容
1. **execute_box_call() ラッパー追加**:
   - src/backend/mir_interpreter/mod.rs に公開 API 実装
   - 1_000_000 番台レジスタで一時値管理
   - 適切なクリーンアップ処理実装

2. **handle_box_call 可視性変更**:
   - src/backend/mir_interpreter/handlers/boxes.rs を pub に変更
   - JoinIR Runner からアクセス可能に

3. **JoinIR Runner BoxCall 統合**:
   - src/mir/join_ir_runner.rs の BoxCall 処理を書き換え
   - StringBox 直接呼び出し削除
   - VM の execute_box_call 経由に変更
   - JoinValue ↔ VMValue 変換で統合

4. **不要な関数削除**:
   - expect_str(), expect_int(), box_to_join_value() 削除
   - VMValue 変換に一本化

5. **テスト更新**:
   - joinir_runner_standalone.rs: VM インスタンス追加
   - joinir_runner_min.rs: VM 再利用

## 期待される効果
✅ Void guards 完全対応 (Void.length() → 0)
✅ PluginBox/InstanceBox 将来対応可能
✅ VM の完全な BoxCall 意味論統一
✅ VM 2号機回避（ガードレール設計成功）

## テスト結果
✅ joinir_runner_standalone_skip_ws ... ok
✅ joinir_runner_standalone_trim ... ok
✅ ビルド成功（0エラー）

## 完了タスク
- [x] MirInterpreter::execute_box_call() 実装
- [x] 1_000_000 レジスタ帯域割り当て
- [x] regs クリーンアップ実装
- [x] JoinIR Runner BoxCall 書き換え
- [x] テスト更新＆PASS確認

🎉 VM 完全意味論統合完了！

src/backend/mir_interpreter/handlers/boxes.rs

@@ -106,7 +106,8 @@ impl MirInterpreter {
         }
     }
 
-    pub(super) fn handle_box_call(
+    /// S-5.2-improved: Made public for JoinIR Runner integration via execute_box_call wrapper
+    pub fn handle_box_call(
         &mut self,
         dst: Option<ValueId>,
         box_val: ValueId,

src/backend/mir_interpreter/mod.rs

@@ -79,6 +79,71 @@ impl MirInterpreter {
         self.static_box_decls.insert(name, decl);
     }
 
+    /// Execute a BoxCall with VM's complete semantics (Phase 27-shortterm S-5.2-improved)
+    ///
+    /// This wrapper allows external modules (e.g., JoinIR Runner) to invoke BoxCall
+    /// with the VM's complete semantics including:
+    /// - Void guards (e.g., Void.length() → 0)
+    /// - PluginBox support (FileBox, NetBox, etc.)
+    /// - InstanceBox policy checks
+    /// - object_fields handling
+    /// - Method re-routing (toString→str)
+    ///
+    /// # Implementation Notes
+    /// - Uses 1_000_000 register range for scratch registers (避ける ID 衝突)
+    /// - Properly cleans up temporary registers after use
+    /// - Delegates to `handle_box_call` for complete VM semantics
+    ///
+    /// # Arguments
+    /// - `receiver`: The box instance (VMValue::BoxRef or primitive)
+    /// - `method`: Method name to invoke
+    /// - `args`: Method arguments as VMValue
+    ///
+    /// # Returns
+    /// Result value as VMValue (may be Void, Int, String, BoxRef, etc.)
+    pub fn execute_box_call(
+        &mut self,
+        receiver: VMValue,
+        method: &str,
+        args: Vec<VMValue>,
+    ) -> Result<VMValue, VMError> {
+        // Allocate temporary register IDs in the 1_000_000 range (not 1000!)
+        // This avoids conflicts with user code and future extensions
+        let base = ValueId(1_000_000);
+        let recv_id = base;
+
+        // Place receiver in register
+        self.regs.insert(recv_id, receiver);
+
+        // Place arguments in consecutive registers
+        let arg_ids: Vec<ValueId> = args
+            .into_iter()
+            .enumerate()
+            .map(|(i, v)| {
+                let id = ValueId(base.0 + 1 + i as u32);
+                self.regs.insert(id, v);
+                id
+            })
+            .collect();
+
+        // Allocate destination register
+        let dst_id = ValueId(base.0 + 1000);
+
+        // Invoke handle_box_call for complete VM semantics
+        self.handle_box_call(Some(dst_id), recv_id, method, &arg_ids)?;
+
+        // Read result (may be Void if method returns nothing)
+        let result = self.regs.remove(&dst_id).unwrap_or(VMValue::Void);
+
+        // Cleanup temporary registers (important to avoid stale values!)
+        self.regs.remove(&recv_id);
+        for id in arg_ids {
+            self.regs.remove(&id);
+        }
+
+        Ok(result)
+    }
+
     /// Ensure static box singleton instance exists, create if not
     /// Returns mutable reference to the singleton instance
     fn ensure_static_box_instance(

src/mir/join_ir_runner.rs

@@ -22,14 +22,16 @@ pub use crate::mir::join_ir_ops::{JoinIrOpError, JoinValue};
 pub type JoinRuntimeError = JoinIrOpError;
 
 pub fn run_joinir_function(
+    vm: &mut crate::backend::mir_interpreter::MirInterpreter,
     module: &JoinModule,
     entry: JoinFuncId,
     args: &[JoinValue],
 ) -> Result<JoinValue, JoinRuntimeError> {
-    execute_function(module, entry, args.to_vec())
+    execute_function(vm, module, entry, args.to_vec())
 }
 
 fn execute_function(
+    vm: &mut crate::backend::mir_interpreter::MirInterpreter,
     module: &JoinModule,
     mut current_func: JoinFuncId,
     mut current_args: Vec<JoinValue>,
@@ -58,7 +60,7 @@ fn execute_function(
         while ip < func.body.len() {
             match &func.body[ip] {
                 JoinInst::Compute(inst) => {
-                    eval_compute(inst, &mut locals)?;
+                    eval_compute(vm, inst, &mut locals)?;
                     ip += 1;
                 }
                 JoinInst::Call {
@@ -74,7 +76,7 @@ fn execute_function(
                     }
                     let resolved_args = materialize_args(args, &locals)?;
                     if let Some(dst_var) = dst {
-                        let value = execute_function(module, *target, resolved_args)?;
+                        let value = execute_function(vm, module, *target, resolved_args)?;
                         locals.insert(*dst_var, value);
                         ip += 1;
                     } else {
@@ -113,7 +115,11 @@ fn execute_function(
     }
 }
 
-fn eval_compute(inst: &MirLikeInst, locals: &mut HashMap<VarId, JoinValue>) -> Result<(), JoinRuntimeError> {
+fn eval_compute(
+    vm: &mut crate::backend::mir_interpreter::MirInterpreter,
+    inst: &MirLikeInst,
+    locals: &mut HashMap<VarId, JoinValue>,
+) -> Result<(), JoinRuntimeError> {
     match inst {
         MirLikeInst::Const { dst, value } => {
             let v = match value {
@@ -138,57 +144,48 @@ fn eval_compute(inst: &MirLikeInst, locals: &mut HashMap<VarId, JoinValue>) -> R
             let v = crate::mir::join_ir_ops::eval_compare(*op, &l, &r)?;
             locals.insert(*dst, v);
         }
-        // S-5.2: BoxCall → VM method_router 経由（ガードレール設計）
+        // S-5.2-improved: BoxCall → VM execute_box_call ラッパー経由
         // - 制御フロー: JoinIR Runner が担当
-        // - Box/Plugin 実装: Rust VM に委譲（VM 2号機を避ける）
+        // - Box/Plugin 実装: Rust VM に完全委譲（VM 2号機を避ける）
+        // - VM の完全な BoxCall 意味論を使用:
+        //   * Void guards (Void.length() → 0)
+        //   * PluginBox サポート (FileBox, NetBox)
+        //   * InstanceBox policy checks
+        //   * object_fields handling
+        //   * Method re-routing (toString→str)
         MirLikeInst::BoxCall {
             dst,
-            box_name,
+            box_name: _,  // box_name は VM が内部で判定するため不要
             method,
             args,
         } => {
-            if box_name != "StringBox" {
+            // First argument is the receiver (box instance)
-                return Err(JoinRuntimeError::new(format!(
+            if args.is_empty() {
-                    "Unsupported box call target: {}",
-                    box_name
-                )));
-            }
-            match method.as_str() {
-                "length" => {
-                    let arg = expect_str(&read_var(locals, args[0])?)?;
-                    // S-5.2: VM の StringBox.length() 実装を使用（hardcoded 削除）
-                    let string_box = crate::boxes::basic::StringBox::new(arg);
-                    let result_box = string_box.length();
-                    let result_value = box_to_join_value(result_box)?;
-                    let dst_var = dst.ok_or_else(|| {
-                        JoinRuntimeError::new("length call requires destination")
-                    })?;
-                    locals.insert(dst_var, result_value);
-                }
-                "substring" => {
-                    if args.len() != 3 {
                 return Err(JoinRuntimeError::new(
-                            "substring expects 3 arguments (s, start, end)",
+                    "BoxCall requires at least a receiver argument",
                 ));
             }
-                    let s = expect_str(&read_var(locals, args[0])?)?;
+
-                    let start = expect_int(&read_var(locals, args[1])?)? as usize;
+            // Convert receiver to VMValue
-                    let end = expect_int(&read_var(locals, args[2])?)? as usize;
+            let receiver_jv = read_var(locals, args[0])?;
-                    // S-5.2: VM の StringBox.substring() 実装を使用（hardcoded 削除）
+            let receiver_vm = receiver_jv.to_vm_value();
-                    let string_box = crate::boxes::basic::StringBox::new(s);
+
-                    let result_box = string_box.substring(start, end);
+            // Convert remaining arguments to VMValue
-                    let result_value = box_to_join_value(result_box)?;
+            let method_args_vm: Vec<crate::backend::VMValue> = args[1..]
-                    let dst_var = dst.ok_or_else(|| {
+                .iter()
-                        JoinRuntimeError::new("substring call requires destination")
+                .map(|&var_id| read_var(locals, var_id).map(|jv| jv.to_vm_value()))
-                    })?;
+                .collect::<Result<Vec<_>, _>>()?;
-                    locals.insert(dst_var, result_value);
+
-                }
+            // Invoke VM's execute_box_call for complete semantics
-                _ => {
+            let result_vm = vm.execute_box_call(receiver_vm, method, method_args_vm)
-                    return Err(JoinRuntimeError::new(format!(
+                .map_err(|e| JoinRuntimeError::new(format!("BoxCall failed: {}", e)))?;
-                        "Unsupported StringBox method: {}",
+
-                        method
+            // Convert result back to JoinValue
-                    )))
+            let result_jv = crate::mir::join_ir_ops::JoinValue::from_vm_value(&result_vm)?;
-                }
+
+            // Store result if destination is specified
+            if let Some(dst_var) = dst {
+                locals.insert(*dst_var, result_jv);
             }
         }
     }
@@ -221,44 +218,3 @@ fn as_bool(value: &JoinValue) -> Result<bool, JoinRuntimeError> {
     }
 }
 
-fn expect_int(value: &JoinValue) -> Result<i64, JoinRuntimeError> {
-    match value {
-        JoinValue::Int(i) => Ok(*i),
-        other => Err(JoinRuntimeError::new(format!(
-            "Expected int, got {:?}",
-            other
-        ))),
-    }
-}
-
-fn expect_str(value: &JoinValue) -> Result<String, JoinRuntimeError> {
-    match value {
-        JoinValue::Str(s) => Ok(s.clone()),
-        other => Err(JoinRuntimeError::new(format!(
-            "Expected string, got {:?}",
-            other
-        ))),
-    }
-}
-
-/// S-5.2: Convert Box<dyn NyashBox> from VM to JoinValue
-///
-/// Tries to downcast to known primitive types first (IntegerBox, BoolBox, StringBox),
-/// otherwise wraps as BoxRef for future use.
-fn box_to_join_value(nyash_box: Box<dyn crate::box_trait::NyashBox>) -> Result<JoinValue, JoinRuntimeError> {
-    use std::sync::Arc;
-
-    // Try to downcast to known primitive types first
-    if let Some(int_box) = nyash_box.as_any().downcast_ref::<crate::boxes::basic::IntegerBox>() {
-        return Ok(JoinValue::Int(int_box.value));
-    }
-    if let Some(bool_box) = nyash_box.as_any().downcast_ref::<crate::boxes::basic::BoolBox>() {
-        return Ok(JoinValue::Bool(bool_box.value));
-    }
-    if let Some(str_box) = nyash_box.as_any().downcast_ref::<crate::boxes::basic::StringBox>() {
-        return Ok(JoinValue::Str(str_box.value.clone()));
-    }
-
-    // Otherwise, wrap as BoxRef (for S-5.3/S-5.4 future use)
-    Ok(JoinValue::BoxRef(Arc::from(nyash_box)))
-}

src/tests/joinir_runner_min.rs

@@ -65,7 +65,9 @@ static box Runner {
 
     let join_module =
         lower_skip_ws_to_joinir(&compiled.module).expect("lower_skip_ws_to_joinir failed");
+    // S-5.2-improved: Reuse VM instance for JoinIR Runner
     let join_result = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0),
         &[JoinValue::Str("   abc".to_string())],
@@ -126,7 +128,9 @@ static box Runner {
 
     let join_module = lower_funcscanner_trim_to_joinir(&compiled.module)
         .expect("lower_funcscanner_trim_to_joinir failed");
+    // S-5.2-improved: Reuse VM instance for JoinIR Runner
     let join_result = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0),
         &[JoinValue::Str("   abc  ".to_string())],

src/tests/joinir_runner_standalone.rs

@@ -60,8 +60,12 @@ fn joinir_runner_standalone_skip_ws() {
 
     let join_module = build_skip_ws_joinir();
 
+    // S-5.2-improved: Create MirInterpreter instance for VM integration
+    let mut vm = crate::backend::mir_interpreter::MirInterpreter::new();
+
     // Test case 1: "   abc" → 3
     let result = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0), // entry function
         &[JoinValue::Str("   abc".to_string())],
@@ -74,6 +78,7 @@ fn joinir_runner_standalone_skip_ws() {
 
     // Test case 2: "" → 0
     let result_empty = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0),
         &[JoinValue::Str("".to_string())],
@@ -86,6 +91,7 @@ fn joinir_runner_standalone_skip_ws() {
 
     // Test case 3: "abc" → 0
     let result_no_ws = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0),
         &[JoinValue::Str("abc".to_string())],
@@ -143,8 +149,12 @@ fn joinir_runner_standalone_trim() {
 
     let join_module = build_trim_joinir();
 
+    // S-5.2-improved: Create MirInterpreter instance for VM integration
+    let mut vm = crate::backend::mir_interpreter::MirInterpreter::new();
+
     // Test case 1: "   abc  " → "abc  " (simplified - only leading whitespace)
     let result = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0), // entry function
         &[JoinValue::Str("   abc  ".to_string())],
@@ -157,6 +167,7 @@ fn joinir_runner_standalone_trim() {
 
     // Test case 2: "" → ""
     let result_empty = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0),
         &[JoinValue::Str("".to_string())],
@@ -169,6 +180,7 @@ fn joinir_runner_standalone_trim() {
 
     // Test case 3: "abc" → "abc"
     let result_no_ws = run_joinir_function(
+        &mut vm,
         &join_module,
         JoinFuncId::new(0),
         &[JoinValue::Str("abc".to_string())],