STMT FUNC: allow other variables to be declared alongside statement f…

…unction return var

loki/frontend/fparser.py

@@ -1812,11 +1812,12 @@ def visit_Subroutine_Subprogram(self, o, **kwargs):
             rescope_symbols=True, source=source, incomplete=False
         )
 
-        # Once statement functions are in place, we need to update the original declaration symbol
+        # Once statement functions are in place, we need to update the original declaration so that it
+        # contains ProcedureSymbols rather than Scalars
         for decl in FindNodes(ir.VariableDeclaration).visit(spec):
             if any(routine.symbol_attrs[s.name].is_stmt_func for s in decl.symbols):
-                assert all(routine.symbol_attrs[s.name].is_stmt_func for s in decl.symbols)
-                decl._update(symbols=tuple(s.clone() for s in decl.symbols))
+                decl._update(symbols=tuple(s.clone() if routine.symbol_attrs[s.name].is_stmt_func else s
+                                           for s in decl.symbols))
 
         # Big, but necessary hack:
         # For deferred array dimensions on allocatables, we infer the conceptual

tests/test_subroutine.py

@@ -1493,8 +1493,7 @@ def test_subroutine_stmt_func(here, frontend):
     integer, intent(in) :: a
     integer, intent(out) :: b
     integer :: array(a)
-    integer :: i, j
-    integer :: plus, minus
+    integer :: i, j, plus, minus
     plus(i, j) = i + j
     minus(i, j) = i - j
     integer :: mult