phase29am(p3): align core exit with frag exitmap

src/mir/builder/control_flow/plan/verifier.rs

@@ -17,7 +17,7 @@
 //! - V8: Frag entry matches header_bb
 //! - V9: block_effects contains header_bb
 //! - V10: body_bb effects go in loop_plan.body (block_effects[body_bb] must be empty)
-//! - V11: Exit must be last in Seq/If branch
+//! - V11: Exit must be last in Seq/If branch (ExitMap alignment)
 //! - V12: Loop.body must be Effect-only (Seq-of-effects allowed)
 //!
 //! Phase 273 P3: V1 (Carrier completeness) removed with CoreCarrierInfo
@@ -473,6 +473,28 @@ mod tests {
         assert!(result.unwrap_err().contains("[V11]"));
     }
 
+    #[test]
+    fn test_verify_if_exit_not_last_fails() {
+        let if_plan = CoreIfPlan {
+            condition: ValueId(1),
+            then_plans: vec![
+                CorePlan::Exit(CoreExitPlan::Return(None)),
+                CorePlan::Effect(CoreEffectPlan::Const {
+                    dst: ValueId(2),
+                    value: ConstValue::Integer(1),
+                }),
+            ],
+            else_plans: Some(vec![CorePlan::Effect(CoreEffectPlan::Const {
+                dst: ValueId(3),
+                value: ConstValue::Integer(2),
+            })]),
+        };
+        let plan = CorePlan::If(if_plan);
+        let result = PlanVerifier::verify(&plan);
+        assert!(result.is_err());
+        assert!(result.unwrap_err().contains("[V11]"));
+    }
+
     #[test]
     fn test_v10_body_bb_effects_in_block_effects_fails() {
         // V10: body_bb effects must be empty in block_effects