Frontend: Remove OFP symbol and use Frontend.OFP internally

This should make it unavailable to all tests, but keep the basic
functionality intact.

loki/frontend/ofp.py

@@ -22,7 +22,7 @@
 
 from loki.frontend.source import extract_source, extract_source_from_range
 from loki.frontend.preprocessing import sanitize_registry
-from loki.frontend.util import OFP, sanitize_ir
+from loki.frontend.util import sanitize_ir, Frontend
 
 from loki import ir
 from loki.ir import (
@@ -47,6 +47,9 @@
 __all__ = ['HAVE_OFP', 'parse_ofp_file', 'parse_ofp_source', 'parse_ofp_ast']
 
 
+OFP = Frontend.OFP
+
+
 @Timer(logger=debug, text=lambda s: f'[Loki::OFP] Executed parse_ofp_file in {s:.2f}s')
 @disk_cached(argname='filename', suffix='ofpast')
 def parse_ofp_file(filename):

loki/frontend/preprocessing.py

@@ -19,12 +19,15 @@
 from loki.config import config
 from loki.tools import as_tuple, gettempdir, filehash
 from loki.ir import VariableDeclaration, Intrinsic, FindNodes
-from loki.frontend.util import OMNI, OFP, FP, REGEX
+from loki.frontend.util import OMNI, FP, REGEX, Frontend
 
 
 __all__ = ['preprocess_cpp', 'sanitize_input', 'sanitize_registry', 'PPRule']
 
 
+OFP = Frontend.OFP
+
+
 def preprocess_cpp(source, filepath=None, includes=None, defines=None):
     """
     Invoke an external C-preprocessor to sanitize input files.

loki/frontend/util.py

@@ -26,7 +26,7 @@
 
 
 __all__ = [
-    'Frontend', 'OFP', 'OMNI', 'FP', 'REGEX', 'available_frontends',
+    'Frontend', 'OMNI', 'FP', 'REGEX', 'available_frontends',
     'read_file', 'InlineCommentTransformer',
     'ClusterCommentTransformer', 'CombineMultilinePragmasTransformer',
     'sanitize_ir'
@@ -50,7 +50,6 @@ def __str__(self):
         return self.name.lower()  # pylint: disable=no-member
 
 OMNI = Frontend.OMNI
-OFP = Frontend.OFP
 FP = Frontend.FP
 REGEX = Frontend.REGEX
 
@@ -113,7 +112,7 @@ def my_test(frontend):
     # Build the list of parameters
     params = []
     for f in Frontend:
-        if f == OFP:
+        if f == Frontend.OFP:
             continue  # OFP is now deprecated!
         if f in skip:
             params += [pytest.param(f, marks=pytest.mark.skip(reason=skip[f]))]
@@ -383,10 +382,10 @@ def sanitize_ir(_ir, frontend, pp_registry=None, pp_info=None):
         # Revert OMNI's array dimension expansion from `a(n)` => `arr(1:n)`
         _ir = RangeIndexTransformer(invalidate_source=False).visit(_ir)
 
-    if frontend in (OMNI, OFP):
+    if frontend in (OMNI, Frontend.OFP):
         _ir = inline_labels(_ir)
 
-    if frontend in (FP, OFP):
+    if frontend in (FP, Frontend.OFP):
         _ir = CombineMultilinePragmasTransformer(inplace=True, invalidate_source=False).visit(_ir)
         _ir = RemoveDuplicateVariableDeclarationsForExternalProcedures(inplace=True, invalidate_source=False).visit(_ir)
 

loki/sourcefile.py

@@ -15,7 +15,7 @@
 from loki.backend.fgen import fgen
 from loki.backend.cufgen import cufgen
 from loki.frontend import (
-    Frontend, OMNI, OFP, FP, REGEX, sanitize_input, Source, read_file, preprocess_cpp,
+    Frontend, OMNI, FP, REGEX, sanitize_input, Source, read_file, preprocess_cpp,
     parse_omni_source, parse_ofp_source, parse_fparser_source,
     parse_omni_ast, parse_ofp_ast, parse_fparser_ast, parse_regex_source,
     RegexParserClass
@@ -32,6 +32,9 @@
 __all__ = ['Sourcefile']
 
 
+OFP = Frontend.OFP
+
+
 class Sourcefile:
     """
     Class to handle and manipulate source files, storing :any:`Module` and