This seems to be a bug when scanning the PL/SQL Block for bind variables, caused by the q'<string>' expression. We'll fix it.
There are 2 workarounds:
1. Don't use q'<string>' expressions:
BEGIN
-- Test statements here
EXECUTE IMMEDIATE 'begin
:1 := regexp_replace(some_func(),''([^/]+/*){1}$'');
end;'
USING OUT :c;
END;
2. Disable the "Automatically scan bind variables before Execute" option on the Configure > Preferences > Window Types > Test Window page. In this case you need to explicitly declare the :C bind variable in the Test Window.
