feat(joinir): Phase 64-1/2 P2型ヒント実装 & 削減条件準備

Phase 64-1: P2/P3 対象関数分類完了
- P2 対象リスト作成: read_quoted_from, IfMerge Simple/Multiple
- P3 将来拡張: MethodCall戻り値型, Box コンストラクタ
- 実装戦略確立: P2から1関数ずつ段階的拡大

Phase 64-2: P2 型ヒント供給実装完了
- read_quoted.rs: ループカウンタ i (Integer), 文字列 ch (String) 型確定
- if_merge.rs: infer_type_from_mir_pattern() 追加 (Const命令から型推論)
- A/B テスト追加: test_p2_if_merge_type_hint() で型ヒント伝播検証 ✅

技術的成果:
- JoinIR MergePair の type_hint 自動推論システム完成
- Phase 63 P1実装パターンを P2 に拡大適用
- 次ステップ: Phase 64-3 lifecycle.rs で P2 hint経路統合

修正ファイル:
- phase-63-joinir-type-info/README.md: Phase 64-1/2 セクション追加
- read_quoted.rs: MergePair 型ヒント追加 (Integer/String)
- if_merge.rs: infer_type_from_mir_pattern() + 型ヒント推論
- mir_joinir_if_select.rs: test_p2_if_merge_type_hint() 追加

🎯 削除条件 4/5 維持 (P1完了), Phase 64-3で P2拡大へ

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/grammar/generated.rs

@@ -36,15 +36,37 @@ pub static OPERATORS_DIV_RULES: &[(&str, &str, &str, &str)] = &[
 ];
 pub fn lookup_keyword(word: &str) -> Option<&'static str> {
     for (k, t) in KEYWORDS {
-        if *k == word {
-            return Some(*t);
-        }
+        if *k == word { return Some(*t); }
     }
     None
 }
 
 pub static SYNTAX_ALLOWED_STATEMENTS: &[&str] = &[
-    "box", "global", "function", "static", "if", "loop", "break", "return", "print", "nowait",
-    "include", "local", "outbox", "try", "throw", "using", "from",
+    "box",
+    "global",
+    "function",
+    "static",
+    "if",
+    "loop",
+    "break",
+    "return",
+    "print",
+    "nowait",
+    "include",
+    "local",
+    "outbox",
+    "try",
+    "throw",
+    "using",
+    "from",
+];
+pub static SYNTAX_ALLOWED_BINOPS: &[&str] = &[
+    "add",
+    "sub",
+    "mul",
+    "div",
+    "and",
+    "or",
+    "eq",
+    "ne",
 ];
-pub static SYNTAX_ALLOWED_BINOPS: &[&str] = &["add", "sub", "mul", "div", "and", "or", "eq", "ne"];

src/mir/join_ir/frontend/ast_lowerer/read_quoted.rs

@@ -401,15 +401,15 @@ impl AstToJoinIrLowerer {
                 merges: vec![
                     MergePair {
                         dst: i_after_esc,
-                        then_val: i_esc,
-                        else_val: step_i,
-                        type_hint: None, // Phase 63-3
+                        then_val: i_esc,  // i + 1 (BinOp::Add, Integer)
+                        else_val: step_i, // i (Integer param)
+                        type_hint: Some(crate::mir::MirType::Integer), // Phase 64-2: ループカウンタ型確定
                     },
                     MergePair {
                         dst: ch_merged,
-                        then_val: ch_esc,
-                        else_val: step_ch,
-                        type_hint: None, // Phase 63-3
+                        then_val: ch_esc,  // substring 結果 (String)
+                        else_val: step_ch, // substring 結果 (String)
+                        type_hint: Some(crate::mir::MirType::String), // Phase 64-2: 文字列型確定
                     },
                 ],
                 k_next: None,

src/mir/join_ir/lowering/if_merge.rs

@@ -15,7 +15,7 @@
 //! - Loop の PHI には触らない（Loop lowering の責務）
 
 use crate::mir::join_ir::{JoinInst, MergePair};
-use crate::mir::{BasicBlockId, MirFunction, MirInstruction, ValueId};
+use crate::mir::{BasicBlockId, MirFunction, MirInstruction, MirType, ValueId};
 use std::collections::HashSet;
 
 // Phase 61-1: If-in-loop context support
@@ -198,11 +198,15 @@ impl IfMergeLowerer {
             // else ブロックで dst に書き込まれる値を探す
             let else_val = self.find_written_value(&else_block.instructions, dst)?;
 
+            // Phase 64-2: then_val / else_val から型ヒント推論
+            let type_hint = infer_type_from_mir_pattern(func, then_val)
+                .or_else(|| infer_type_from_mir_pattern(func, else_val));
+
             merge_pairs.push(MergePair {
                 dst,
                 then_val,
                 else_val,
-                type_hint: None, // Phase 63-3: 現時点では型ヒントなし
+                type_hint, // Phase 64-2: Const 命令から型推論
             });
         }
 
@@ -272,6 +276,34 @@ impl IfMergeLowerer {
     }
 }
 
+/// Phase 64-2: MIR から ValueId の型を推論
+///
+/// Const 命令を探して、ValueId に対応する MirType を返す。
+/// IfMerge の then_val / else_val から型ヒントを埋めるために使用。
+fn infer_type_from_mir_pattern(func: &MirFunction, val_id: ValueId) -> Option<MirType> {
+    use crate::mir::{ConstValue, MirInstruction, MirType};
+
+    // 全ブロックの全命令を走査して Const 命令を探す
+    for block in func.blocks.values() {
+        for inst in &block.instructions {
+            if let MirInstruction::Const { dst, value } = inst {
+                if *dst == val_id {
+                    return Some(match value {
+                        ConstValue::Integer(_) => MirType::Integer,
+                        ConstValue::Bool(_) => MirType::Bool,
+                        ConstValue::String(_) => MirType::String,
+                        ConstValue::Void => MirType::Void,
+                        ConstValue::Null => MirType::Unknown, // Null は Unknown として扱う
+                        // Float は現状未サポート
+                        _ => return None,
+                    });
+                }
+            }
+        }
+    }
+    None
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/tests/mir_joinir_if_select.rs

@@ -719,4 +719,59 @@ mod tests {
 
         std::env::remove_var("NYASH_JOINIR_IF_SELECT");
     }
+
+    /// Phase 64-2-2: A/B テスト - P2 IfMerge Simple 型ヒント検証
+    ///
+    /// IfMerge Simple パターンで MergePair の type_hint が正しく設定されることを確認。
+    /// Phase 64-2 で追加した `infer_type_from_mir_pattern()` の動作確認。
+    #[test]
+    fn test_p2_if_merge_type_hint() {
+        use crate::mir::join_ir::lowering::if_merge::IfMergeLowerer;
+        use crate::mir::MirType;
+
+        std::env::set_var("NYASH_JOINIR_IF_MERGE", "1");
+
+        // P2 IfMerge Simple pattern で IfMerge 生成
+        let func = create_if_merge_simple_pattern_mir();
+        let entry_block = func.entry_block;
+
+        let lowerer = IfMergeLowerer::new(2); // debug_level=2
+        let join_inst = lowerer
+            .lower_if_to_if_merge(&func, entry_block)
+            .expect("P2 IfMerge Simple should lower to IfMerge");
+
+        // IfMerge instruction から merge_pairs を取り出す
+        use crate::mir::join_ir::JoinInst;
+        if let JoinInst::IfMerge { merges, .. } = join_inst {
+            eprintln!("✅ Phase 64-2-2 Step 1: IfMerge instruction found");
+
+            // MergePair の型ヒント確認（Const 命令から Integer を推論）
+            assert!(
+                !merges.is_empty(),
+                "IfMerge should have at least one MergePair"
+            );
+
+            // 最初の MergePair の型ヒントを確認（x に Integer 代入）
+            let first_pair = &merges[0];
+            if let Some(type_hint) = &first_pair.type_hint {
+                eprintln!(
+                    "✅ Phase 64-2-2 Step 2: MergePair[0] type_hint = Some({:?})",
+                    type_hint
+                );
+                assert_eq!(
+                    *type_hint,
+                    MirType::Integer,
+                    "P2 IfMerge Simple should infer Integer type from Const"
+                );
+            } else {
+                panic!("P2 IfMerge Simple should have type_hint=Some(Integer), got None");
+            }
+        } else {
+            panic!("Expected IfMerge instruction, got: {:?}", join_inst);
+        }
+
+        eprintln!("✅ Phase 64-2-2: P2 IfMerge type hint test passed - infer_type_from_mir_pattern() works!");
+
+        std::env::remove_var("NYASH_JOINIR_IF_MERGE");
+    }
 }