RemoveDuplicateArgs: solution for possible name clashes if 'rename_co…

…mmon'

loki/transformations/tests/test_utilities.py

@@ -629,6 +629,7 @@ def test_utilities_remove_duplicate_args(tmp_path, frontend, pass_as_kwarg, recu
   integer, intent(in) :: nlon,nlev
   real, intent(inout) :: b_var(nlon,nlev)
   real, intent(inout) :: a_var(nlon,nlev)
+  real :: VAR ! create name clash on purpose (if rename_common)
   b_var(:,:) = 0.
   a_var(:,:) = 1.0
 end subroutine compute
@@ -676,7 +677,8 @@ def test_utilities_remove_duplicate_args(tmp_path, frontend, pass_as_kwarg, recu
     nested_kernel = nested_kernel_mod['compute']
     nested_kernel_vars = nested_kernel.variable_map
     nested_kernel_args = [arg.name.lower() for arg in nested_kernel.arguments]
-    nested_kernel_var_name = 'var' if rename_common else 'b_var'
+    # it's always 'b_var' as a rename would clash with the already "used" variable "var"
+    nested_kernel_var_name = 'b_var'
     if recurse_to_kernels:
         assert nested_kernel_var_name in nested_kernel_args
         assert 'a_var' not in nested_kernel_args

loki/transformations/utilities.py

@@ -104,6 +104,13 @@ def remove_duplicate_args_call(call):
         return arg_map
 
     def modify_callee(callee, callee_arg_map):
+
+        def allowed_rename(routine, rename):
+            # check whether rename is already "used" in routine
+            if rename in routine.arguments or rename in routine.variables:
+                return False
+            return True
+
         combine = [routine_args for call_arg, routine_args in callee_arg_map.items() if len(routine_args) > 1]
         if rename_common:
             matches = [
@@ -112,6 +119,14 @@ def modify_callee(callee, callee_arg_map):
                 for args in combine
             ]
             rename_common_map = {c[0].name: m for c, m in zip(combine, matches) if m}
+            # check whether found rename is already "used" in routine
+            unallowed_renames = ()
+            for name, rename in rename_common_map.items():
+                if not allowed_rename(callee, rename):
+                    unallowed_renames += (name,)
+            # and if already "used", remove and use instead default
+            for key in unallowed_renames:
+                del rename_common_map[key]
         else:
             rename_common_map = {}
         redundant = flatten([routine_args[1:] for routine_args in combine])