(Closes #512) fix for circular import when importing fparser.two.Fortran2008

src/fparser/two/Fortran2008/label_do_stmt_r816.py

@@ -1,7 +1,7 @@
 # -----------------------------------------------------------------------------
 # BSD 3-Clause License
 #
-# Copyright (c) 2023, Science and Technology Facilities Council.
+# Copyright (c) 2023-2026, Science and Technology Facilities Council.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -37,12 +37,12 @@
     label-do-stmt is [ do-construct-name : ] DO label [ loop-control ]
 
 The only difference to F2003 rule R828 is that we force this rule to
-use the F2008 version of loop-control
+use the F2008 version of loop-control.
 
 """
 
 from fparser.two.Fortran2003 import Label_Do_Stmt as Label_Do_Stmt_2003
-from fparser.two.Fortran2008 import Loop_Control
+from fparser.two.Fortran2008.loop_control_r818 import Loop_Control
 
 
 class Label_Do_Stmt(Label_Do_Stmt_2003):
@@ -52,10 +52,8 @@ class Label_Do_Stmt(Label_Do_Stmt_2003):
     """
 
     @staticmethod
-    def loop_control_cls():
+    def loop_control_cls() -> Loop_Control:
         """
         :returns: Fortran2008 Loop_Control class.
-        :rtype: :py:class:`fparser.two.Fortran2008.Loop_Control`
-
         """
         return Loop_Control

src/fparser/two/tests/fortran2008/test_f2008_import.py

@@ -0,0 +1,52 @@
+# Copyright (c) 2026 Science and Technology Facilities Council
+
+# All rights reserved.
+
+# Modifications made as part of the fparser project are distributed
+# under the following license:
+
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+
+# 3. Neither the name of the copyright holder nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import sys
+import subprocess
+
+"""Tests for the Fortran2008 module as a whole."""
+
+
+def test_fortran2008_import_without_fortran2003_first():
+    """
+    Check that `from fparser.two import Fortran2008` works in a
+    fresh interpreter, i.e. without Fortran2003 having been
+    imported first (which previously masked a circular import bug).
+    """
+    result = subprocess.run(
+        [sys.executable, "-c", "from fparser.two import Fortran2008"],
+        capture_output=True,
+        text=True,
+    )
+    assert result.returncode == 0, result.stderr