From 1aaf5d15c3ce1ba26bdcd9e6a6efe0c3c87a047a Mon Sep 17 00:00:00 2001
From: Gleb Belov <gleb@ampl.com>
Date: Fri, 1 Nov 2024 23:26:17 +1100
Subject: [PATCH] Expressions: for IfThen, algebralize only the then- and
 else-part #237

---
 include/mp/flat/constr_2_expr.h                       | 11 ++++++++++-
 include/mp/flat/constr_keeper.h                       |  4 ++--
 .../cases/categorized/fast/logical/modellist.json     |  4 +++-
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/mp/flat/constr_2_expr.h b/include/mp/flat/constr_2_expr.h
index 6aebc1478..87c2a441b 100644
--- a/include/mp/flat/constr_2_expr.h
+++ b/include/mp/flat/constr_2_expr.h
@@ -387,7 +387,7 @@ class Constraints2Expr {
     return false;
   }
 
-  /// Handle logical expression in an algebraic con
+  /// Handle logical expressions in an algebraic con
   /// @return whether to remove the original \a con.
   template <class Con>
   bool HandleLogicalArgs(const Con& con, int ) {
@@ -395,6 +395,15 @@ class Constraints2Expr {
     return false;                                    // don't remove immediately
   }
 
+  /// Handle logical expressions in an IfThen
+  /// @return whether to remove the original \a con.
+  template <>
+  bool HandleLogicalArgs(const IfThenConstraint& con, int ) {
+    MarkVarIfLogical_(con.GetArguments()[1]);    // then part
+    MarkVarIfLogical_(con.GetArguments()[2]);    // else part
+    return false;
+  }
+
   /// Special linear cases.
   /// Not doing any more because these simplifications
   /// interfere with result variable marking.
diff --git a/include/mp/flat/constr_keeper.h b/include/mp/flat/constr_keeper.h
index 19c4a96f3..1d7e5c112 100644
--- a/include/mp/flat/constr_keeper.h
+++ b/include/mp/flat/constr_keeper.h
@@ -158,8 +158,8 @@ class ConstraintKeeper final
     return false;
   }
 
-  /// Mark whether we could result vars of functional constraints
-  /// as vars, vs using these constraints as expressions
+  /// Mark whether we could use result vars of functional constraints
+  /// as expressions
   void MarkExprResultVars(BasicFlatConverter& cvt) override {
     assert(&cvt == &GetConverter());         // Using the same Converter
     DoMarkForResultVars();
diff --git a/test/end2end/cases/categorized/fast/logical/modellist.json b/test/end2end/cases/categorized/fast/logical/modellist.json
index 1599aa402..50ebc2ecf 100644
--- a/test/end2end/cases/categorized/fast/logical/modellist.json
+++ b/test/end2end/cases/categorized/fast/logical/modellist.json
@@ -45,7 +45,9 @@
     "name" : "ifthen_var cmp:eps=0 chk:fail",
     "tags" : ["logical"],
     "options": {
-      "ANYSOLVER_options": "cvt:cmp:eps=0 chk:fail"
+      "ANYSOLVER_options": "cvt:cmp:eps=0 chk:fail",
+      "mp2nl_options": "solver_options='cvt:cmp:eps=0 chk:fail'"
+
     },
     "values": {
       "solve_result_num": 150