From ca8c557839b7d07f68e86182c94ec7e7712f3974 Mon Sep 17 00:00:00 2001
From: Balthasar Reuter <balthasar.reuter@ecmwf.int>
Date: Wed, 2 Aug 2023 14:32:23 +0100
Subject: [PATCH] Test and fix constructor arg conflict in FindExpressionRoot

---
 loki/expression/expr_visitors.py |  5 ++++-
 tests/test_visitor.py            | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/loki/expression/expr_visitors.py b/loki/expression/expr_visitors.py
index fc3fcfde0..c19ff3ba2 100644
--- a/loki/expression/expr_visitors.py
+++ b/loki/expression/expr_visitors.py
@@ -256,7 +256,10 @@ class FindExpressionRoot(ExpressionFinder):
     """
     def __init__(self, expr, recurse_to_parent=True, **kwargs):
         self._retriever = ExpressionRetriever(lambda e: e is expr, recurse_to_parent=recurse_to_parent)
-        super().__init__(unique=False, retrieve=lambda e: e if self._retriever.retrieve(e) else (), **kwargs)
+        if kwargs.get('unique'):
+            raise ValueError('FindExpressionRoot requires unique=False')
+        kwargs['unique'] = False
+        super().__init__(retrieve=lambda e: e if self._retriever.retrieve(e) else (), **kwargs)
 
 
 class SubstituteExpressions(Transformer):
diff --git a/tests/test_visitor.py b/tests/test_visitor.py
index 5165bd799..b8e90c6ec 100644
--- a/tests/test_visitor.py
+++ b/tests/test_visitor.py
@@ -391,6 +391,30 @@ def test_find_expression_root(frontend):
         assert cast_root[0].source.lines == (13, 13)
 
 
+@pytest.mark.parametrize('frontend', available_frontends())
+def test_find_expression_root_constructor_args(frontend):
+    """
+    Test correct handling for various constructor arguments
+    """
+    fcode = """
+subroutine my_routine
+    implicit none
+    integer :: i
+    i = 1 + 1
+end subroutine my_routine
+    """.strip()
+
+    routine = Subroutine.from_source(fcode, frontend=frontend)
+    exprs = FindExpressions().visit(routine.body)
+    some_expr = [expr for expr in exprs if isinstance(expr, IntLiteral)][0]
+
+    with pytest.raises(ValueError):
+        FindExpressionRoot(some_expr, unique=True).visit(routine.body)
+
+    expr_root = FindExpressionRoot(some_expr, unique=False).visit(routine.body)
+    assert expr_root == (routine.body.body[0].rhs,)
+
+
 @pytest.mark.parametrize('frontend', available_frontends())
 def test_find_variables_associates(frontend):
     """