a filter_global_assignment rule would serve useful in the case that rename_variables changes variable names to already existing global names. I have currently had an issue with the rename_variables rule overriding local variable names to existing global names and causing errors within my script.

It would also be a fair option to ditch this entirely for an extra parameter to also rename globals.

Examples

--unmodified
a = 0;
local b = 1;

print(a);
-- outputs: 0
-- expected output: 0

--rename_variables transform
a = 0;
local a = 1;

print(a);
-- outputs: 1
-- expected output: 0

--filter_global_assignment > rename_variables transform
getfenv().a = 0;
local a = 1;

print(getfenv().a);
-- outputs: 0
-- expected output: 0