feat(mir): Phase 25.1f完了 - Conservative PHI + ControlForm観測レイヤー

🎉 Conservative PHI Box理論による完全SSA構築

**Phase 7-B: Conservative PHI実装**
- 片方branchのみ定義変数に対応（emit_void使用）
- 全変数にPHI生成（Conservative Box理論）
- Stage-1 resolver全テスト緑化（3/3 PASS）

**Phase 25.1f: ControlForm観測レイヤー**
- LoopShape/IfShape/ControlForm構造定義
- Loop/If統一インターフェース実装
- debug_dump/debug_validate機能追加
- NYASH_CONTROL_FORM_TRACE環境変数対応

**主な変更**:
- src/mir/builder/phi.rs: Conservative PHI実装
- src/mir/control_form.rs: ControlForm構造（NEW）
- src/mir/loop_builder.rs: LoopForm v2デフォルト化

**テスト結果**:
✅ mir_stage1_using_resolver_min_fragment_verifies
✅ mir_stage1_using_resolver_full_collect_entries_verifies
✅ mir_parserbox_parse_program2_harness_parses_minimal_source

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: ChatGPT <chatgpt@openai.com>

src/mir/builder/calls/call_unified.rs

@@ -5,11 +5,8 @@
  * Replaces 6 different call instructions with a single unified system
  */
 
-use crate::mir::{Callee, Effect, EffectMask, ValueId};
-use crate::mir::definitions::call_unified::{CallFlags, MirCall, TypeCertainty};
-use super::call_target::CallTarget;
-use super::method_resolution;
-use super::extern_calls;
+use crate::mir::{Callee, EffectMask, ValueId};
+use crate::mir::definitions::call_unified::{CallFlags, MirCall};
 
 /// Check if unified call system is enabled
 pub fn is_unified_call_enabled() -> bool {

src/mir/builder/calls/emit.rs

@@ -5,9 +5,9 @@
 //! - emit_legacy_call: レガシーCall発行（既存互換）
 //! - emit_global_call/emit_method_call/emit_constructor_call: 便利ラッパー
 
-use super::super::{Effect, EffectMask, MirBuilder, MirInstruction, ValueId};
+use super::super::{EffectMask, MirBuilder, MirInstruction, ValueId};
 use crate::mir::definitions::call_unified::Callee;
-use super::{CallTarget, call_unified};
+use super::CallTarget;
 
 impl MirBuilder {
     /// Unified call emission - delegates to UnifiedCallEmitterBox
@@ -139,6 +139,7 @@ impl MirBuilder {
     // ========================================
 
     /// Try fallback handlers for global functions (delegates to CallMaterializerBox)
+    #[allow(dead_code)]
     pub(super) fn try_global_fallback_handlers(
         &mut self,
         dst: Option<ValueId>,
@@ -149,6 +150,7 @@ impl MirBuilder {
     }
 
     /// Ensure receiver is materialized in Callee::Method (delegates to CallMaterializerBox)
+    #[allow(dead_code)]
     pub(super) fn materialize_receiver_in_callee(
         &mut self,
         callee: Callee,

src/mir/builder/calls/extern_calls.rs

@@ -155,6 +155,7 @@ pub fn parse_extern_name(name: &str) -> (String, String) {
 }
 
 /// Check if a name refers to an environment interface
+#[allow(dead_code)]
 pub fn is_env_interface(name: &str) -> bool {
     matches!(name,
         "env" | "env.console" | "env.fs" | "env.net" |

src/mir/builder/calls/function_lowering.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 /*!
  * Function Lowering Utilities
  *
@@ -147,4 +149,4 @@ pub fn method_likely_returns_value(method_name: &str) -> bool {
         "add" | "sub" | "mul" | "div" |
         "min" | "max" | "abs"
     )
-}
+}

src/mir/builder/calls/guard.rs

@@ -96,6 +96,7 @@ impl<'a> CalleeGuardBox<'a> {
     /// receiver型の検証（ヘルパー）
     ///
     /// 指定されたreceiverがBox型を持っているか確認
+    #[allow(dead_code)]
     pub fn has_box_type(&self, receiver: ValueId) -> bool {
         matches!(self.value_types.get(&receiver), Some(MirType::Box(_)))
     }
@@ -103,6 +104,7 @@ impl<'a> CalleeGuardBox<'a> {
     /// receiver型の取得（ヘルパー）
     ///
     /// 指定されたreceiverのBox型名を返す（存在しない場合はNone）
+    #[allow(dead_code)]
     pub fn get_box_type(&self, receiver: ValueId) -> Option<&String> {
         match self.value_types.get(&receiver) {
             Some(MirType::Box(box_name)) => Some(box_name),
@@ -114,6 +116,7 @@ impl<'a> CalleeGuardBox<'a> {
     ///
     /// box_name と receiver型が一致するか判定
     /// （静的メソッド呼び出しの検出用）
+    #[allow(dead_code)]
     pub fn is_me_call(&self, box_name: &str, receiver: ValueId) -> bool {
         match self.get_box_type(receiver) {
             Some(recv_box) => recv_box == box_name,

src/mir/builder/calls/mod.rs

@@ -28,8 +28,13 @@ pub mod effects_analyzer; // Phase 3-B: Effects analyzer (エフェクト解析
 pub mod materializer;     // Phase 3-C: Call materializer (Call前処理・準備専用箱)
 
 // Re-export public interfaces
+#[allow(unused_imports)]
 pub use call_target::CallTarget;
+#[allow(unused_imports)]
 pub use lowering::*;
+#[allow(unused_imports)]
 pub use utils::*;
+#[allow(unused_imports)]
 pub use emit::*;
+#[allow(unused_imports)]
 pub use build::*;

src/mir/builder/calls/special_handlers.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 /*!
  * Special Call Handlers
  *
@@ -137,4 +139,4 @@ pub fn suggest_alternative_for_reserved(name: &str) -> String {
         "from" => "Use 'from Parent.method()' syntax for delegation".to_string(),
         _ => format!("'{}' is a reserved keyword", name),
     }
-}
+}