From a2b3e450d23d565d2e0e38f1f9d22d813b4f6059 Mon Sep 17 00:00:00 2001
From: Roland Kaminski <kaminski@cs.uni-potsdam.de>
Date: Mon, 18 May 2026 10:38:27 +0200
Subject: [PATCH] fix occurs check for projection

---
 lib/cxx-api/tests/solve.cc          | 11 +++++++++++
 lib/input/src/rewrite/dependency.cc |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/cxx-api/tests/solve.cc b/lib/cxx-api/tests/solve.cc
index a4bc0db87..a9ea2c2f8 100644
--- a/lib/cxx-api/tests/solve.cc
+++ b/lib/cxx-api/tests/solve.cc
@@ -202,4 +202,15 @@ TEST_CASE("solve consequence", "[cxx][solve][consequence]") {
     }
 }
 
+TEST_CASE("solve bug project", "[cxx][solve][project]") {
+    auto lib = Library{};
+    auto ctl = Control{lib};
+    ctl.parse_string("c. { a(f(t)) }. d :- b. e(X) :- a(X). b :- c, e(f(X)). :- not b.");
+    ctl.ground();
+    auto models = std::vector<std::vector<std::string>>{};
+    auto mcb = MCB{models};
+    REQUIRE(ctl.solve({}, mcb).satisfiable());
+    REQUIRE(models == std::vector<std::vector<std::string>>{{"a(f(t))", "b", "c", "d", "e(f(t))"}});
+}
+
 } // namespace Clingo::Test
diff --git a/lib/input/src/rewrite/dependency.cc b/lib/input/src/rewrite/dependency.cc
index f8df40093..10ab14273 100644
--- a/lib/input/src/rewrite/dependency.cc
+++ b/lib/input/src/rewrite/dependency.cc
@@ -226,7 +226,7 @@ class Unifier {
             if (auto const *term = std::get_if<Term>(&arg); term != nullptr) {
                 return occurs_check_(name, *term);
             }
-            return false;
+            return true;
         });
     }