From dd84f87edba9b0cde271fe7000208c5f8f97b890 Mon Sep 17 00:00:00 2001
From: Andrew Reynolds <andrew.j.reynolds@gmail.com>
Date: Thu, 12 Mar 2020 16:13:27 -0500
Subject: [PATCH] Do not allow quantifiers over real variables in real to int
 pass. (#4049)

With quantifiers over real variables, --solve-real-as-int is neither sound nor complete. Thus we should abort in this case.
---
 src/preprocessing/passes/real_to_int.cpp      | 10 ++++--
 test/regress/CMakeLists.txt                   |  1 -
 .../push-pop/issue3915-real-as-int.smt2       | 33 -------------------
 3 files changed, 7 insertions(+), 37 deletions(-)
 delete mode 100644 test/regress/regress0/push-pop/issue3915-real-as-int.smt2

diff --git a/src/preprocessing/passes/real_to_int.cpp b/src/preprocessing/passes/real_to_int.cpp
index f50cecd1b..1c77f6f54 100644
--- a/src/preprocessing/passes/real_to_int.cpp
+++ b/src/preprocessing/passes/real_to_int.cpp
@@ -115,7 +115,7 @@ Node RealToInt::realToIntInternal(TNode n, NodeMap& cache, std::vector<Node>& va
                 {
                   throw TypeCheckingException(
                       v.toExpr(),
-                      string("Cannot translate to Int: ") + v.toString());
+                      std::string("Cannot translate to Int: ") + v.toString());
                 }
               }
             }
@@ -166,8 +166,12 @@ Node RealToInt::realToIntInternal(TNode n, NodeMap& cache, std::vector<Node>& va
       {
         if (n.getKind() == kind::BOUND_VARIABLE)
         {
-          // special case for bound variables (must call mkBoundVar)
-          ret = nm->mkBoundVar(nm->integerType());
+          // cannot change the type of quantified variables, since this leads
+          // to incompleteness.
+          throw TypeCheckingException(
+              n.toExpr(),
+              std::string("Cannot translate bound variable to Int: ")
+                  + n.toString());
         }
         else if (n.isVar())
         {
diff --git a/test/regress/CMakeLists.txt b/test/regress/CMakeLists.txt
index de2091ef6..c23ed07ee 100644
--- a/test/regress/CMakeLists.txt
+++ b/test/regress/CMakeLists.txt
@@ -690,7 +690,6 @@ set(regress_0_tests
   regress0/push-pop/incremental-subst-bug.cvc
   regress0/push-pop/issue1986.smt2
   regress0/push-pop/issue2137.min.smt2
-  regress0/push-pop/issue3915-real-as-int.smt2
   regress0/push-pop/quant-fun-proc-unfd.smt2
   regress0/push-pop/real-as-int-incremental.smt2
   regress0/push-pop/simple_unsat_cores.smt2
diff --git a/test/regress/regress0/push-pop/issue3915-real-as-int.smt2 b/test/regress/regress0/push-pop/issue3915-real-as-int.smt2
deleted file mode 100644
index ad6ba3b33..000000000
--- a/test/regress/regress0/push-pop/issue3915-real-as-int.smt2
+++ /dev/null
@@ -1,33 +0,0 @@
-; COMMAND-LINE: --incremental --check-models --solve-real-as-int
-; EXPECT: sat
-(set-logic UFNIA)
-(set-option :incremental true)
-(set-option :check-models true)
-(set-option :solve-real-as-int true)
-(declare-const v0 Bool)
-(declare-const v1 Bool)
-(declare-const v2 Bool)
-(declare-const v3 Bool)
-(declare-const v4 Bool)
-(declare-const v5 Bool)
-(declare-const v6 Bool)
-(declare-const v7 Bool)
-(declare-const v8 Bool)
-(declare-const v9 Bool)
-(declare-const v10 Bool)
-(declare-const v11 Bool)
-(declare-const v12 Bool)
-(declare-const v13 Bool)
-(declare-const v14 Bool)
-(declare-const i1 Int)
-(assert (forall ((q0 Int) (q1 Int) (q2 Int) (q3 Bool)) (=> (= v7 q3 v7 q3 v0 q3 q3 q3 q3 v3) (> q0 59))))
-(push 1)
-(declare-const v15 Bool)
-(declare-sort S0 0)
-(declare-sort S1 0)
-(declare-const i2 Int)
-(assert v13)
-(push 1)
-(declare-const S1-0 S1)
-(assert (forall ((q4 Int)) (not (distinct q4 q4))))
-(check-sat)
-- 
2.30.2