Span trace utilities and runner source hint

src/mir/loop_builder.rs

@@ -811,6 +811,7 @@ impl<'a> LoopBuilder<'a> {
                 // Phi命令は必ずブロックの先頭に配置。ただし同一dstの既存PHIがある場合は差し替える。
                 let mut replaced = false;
                 let mut idx = 0;
+                let span = self.parent_builder.current_span;
                 while idx < block.instructions.len() {
                     match &mut block.instructions[idx] {
                         MirInstruction::Phi {
@@ -818,6 +819,13 @@ impl<'a> LoopBuilder<'a> {
                             inputs: ins,
                         } if *d == dst => {
                             *ins = inputs.clone();
+                            if block.instruction_spans.len() <= idx {
+                                // Backfill missing spans to preserve alignment after legacy inserts.
+                                while block.instruction_spans.len() <= idx {
+                                    block.instruction_spans.push(crate::ast::Span::unknown());
+                                }
+                            }
+                            block.instruction_spans[idx] = span;
                             replaced = true;
                             break;
                         }
@@ -833,6 +841,7 @@ impl<'a> LoopBuilder<'a> {
                         inputs: inputs.clone(),
                     };
                     block.instructions.insert(0, phi_inst);
+                    block.instruction_spans.insert(0, span);
                 }
                 if dbg {
                     eprintln!("[DEBUG]   ✅ PHI instruction inserted at position 0");
@@ -895,7 +904,8 @@ impl<'a> LoopBuilder<'a> {
     // =============================================================
     // Variable Map Utilities — snapshots and rebinding
     // =============================================================
-    fn get_current_variable_map(&self) -> BTreeMap<String, ValueId> { // Phase 25.1: BTreeMap化
+    fn get_current_variable_map(&self) -> BTreeMap<String, ValueId> {
+        // Phase 25.1: BTreeMap化
         self.parent_builder.variable_map.clone()
     }
 
@@ -921,6 +931,8 @@ impl<'a> LoopBuilder<'a> {
     }
 
     fn build_statement(&mut self, stmt: ASTNode) -> Result<ValueId, String> {
+        // Preserve the originating span for loop-local control instructions (break/continue/phi).
+        self.parent_builder.current_span = stmt.span();
         match stmt {
             // Ensure nested bare blocks inside loops are lowered with loop-aware semantics
             ASTNode::Program { statements, .. } => {
@@ -1210,15 +1222,15 @@ impl<'a> LoopBuilder<'a> {
         // Phase 26-F-3: ループ内if-mergeコンテキスト設定（ChatGPT設計）
         // pre_if_var_mapにある全変数をcarrier候補として扱う（保守的だが安全）
         // 理由: ループ内変数は全てキャリア候補の可能性があるため
-        let carrier_names: std::collections::BTreeSet<String> =
-            pre_if_var_map.keys()
-                .filter(|name| !name.starts_with("__pin$"))  // 一時変数除外
-                .cloned()
-                .collect();
+        let carrier_names: std::collections::BTreeSet<String> = pre_if_var_map
+            .keys()
+            .filter(|name| !name.starts_with("__pin$")) // 一時変数除外
+            .cloned()
+            .collect();
 
         phi_builder.set_if_context(
-            true,  // in_loop_body = true
-            carrier_names
+            true, // in_loop_body = true
+            carrier_names,
         );
 
         // Phase 26-F-2: IfBodyLocalMergeBox は phi_builder_box.rs 内で直接使用