From da03399e50e33acd4d4a6534205a67d03f44f4c1 Mon Sep 17 00:00:00 2001
From: Andrew Reynolds <andrew.j.reynolds@gmail.com>
Date: Tue, 6 Apr 2021 07:28:59 -0500
Subject: Fix issue with lemma during equality engine iterator in sets (#6289)

Fixes #4370.
---
 src/theory/sets/theory_sets_private.cpp                   | 4 ++++
 test/regress/CMakeLists.txt                               | 2 ++
 test/regress/regress1/sets/issue4370-2-lemma-ee-iter.smt2 | 7 +++++++
 test/regress/regress1/sets/issue4370-4-lemma-ee-iter.smt2 | 8 ++++++++
 4 files changed, 21 insertions(+)
 create mode 100644 test/regress/regress1/sets/issue4370-2-lemma-ee-iter.smt2
 create mode 100644 test/regress/regress1/sets/issue4370-4-lemma-ee-iter.smt2

diff --git a/src/theory/sets/theory_sets_private.cpp b/src/theory/sets/theory_sets_private.cpp
index ea7e773b7..bb4080578 100644
--- a/src/theory/sets/theory_sets_private.cpp
+++ b/src/theory/sets/theory_sets_private.cpp
@@ -286,6 +286,10 @@ void TheorySetsPrivate::fullEffortCheck()
           d_card_enabled = true;
           // register it with the cardinality solver
           d_cardSolver->registerTerm(n);
+          if (d_im.hasSent())
+          {
+            break;
+          }
           // if we do not handle the kind, set incomplete
           Kind nk0 = n[0].getKind();
           // some kinds of cardinality we cannot handle
diff --git a/test/regress/CMakeLists.txt b/test/regress/CMakeLists.txt
index 6bff05bdb..49b7b0543 100644
--- a/test/regress/CMakeLists.txt
+++ b/test/regress/CMakeLists.txt
@@ -1969,6 +1969,8 @@ set(regress_1_tests
   regress1/sets/issue2568.smt2
   regress1/sets/issue2904.smt2
   regress1/sets/issue4124-need-check.smt2
+  regress1/sets/issue4370-2-lemma-ee-iter.smt2
+  regress1/sets/issue4370-4-lemma-ee-iter.smt2
   regress1/sets/issue4391-card-lasso.smt2
   regress1/sets/issue5271.smt2
   regress1/sets/issue5309.smt2
diff --git a/test/regress/regress1/sets/issue4370-2-lemma-ee-iter.smt2 b/test/regress/regress1/sets/issue4370-2-lemma-ee-iter.smt2
new file mode 100644
index 000000000..aa7349261
--- /dev/null
+++ b/test/regress/regress1/sets/issue4370-2-lemma-ee-iter.smt2
@@ -0,0 +1,7 @@
+(set-logic ALL)
+(set-info :status unsat)
+(declare-fun st1 () (Set Int))
+(declare-fun st7 () (Set Int))
+(assert (> 0 (card (intersection st1 (union st7 st1)))))
+(assert (subset st1 st7))
+(check-sat)
diff --git a/test/regress/regress1/sets/issue4370-4-lemma-ee-iter.smt2 b/test/regress/regress1/sets/issue4370-4-lemma-ee-iter.smt2
new file mode 100644
index 000000000..95425709d
--- /dev/null
+++ b/test/regress/regress1/sets/issue4370-4-lemma-ee-iter.smt2
@@ -0,0 +1,8 @@
+(set-logic ALL)
+(set-info :status unsat)
+(declare-fun st3 () (Set String))
+(declare-fun st9 () (Set String))
+(assert (is_singleton (intersection st3 st9)))
+(assert (< 1 (card (intersection st3 st9))))
+(assert (is_singleton st9))
+(check-sat)
-- 
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