Local error actions for nested state machines

[gh-andre]

I ran into local error handling that I wasn't quite expecting from the docs and while I found the syntax that works, I wonder if someone can provide any insights into whether this is the intended way of handling local errors in nested state machines.

This is my initial state machine, with the intent to handle bad [cd ]+ sequences via the bad_cd action:

machine cdxy;

action bad_cd {prn("bad_cd", b, p);}
action bad_cd_sp {prn("bad_cd_sp", b, p);}
action cd_val {prn("cd_val", b, p);}
action my_xy_l {prn("my_xy_l", b, p);}

cd_sp = [cd ]+ %(cd_val) $lerr(bad_cd);

main := 
    ( cd_sp ( ";" cd_sp)* ) $lerr(bad_cd_sp)
    :>> "xy" %(my_xy_l);

However, surprisingly this generates a state machine that calls cd_val and bad_cd in the same transition, such as 2 > 3 or 2 > 1.

I was ready to chalk it up to a bug, but then I realized that the local error might be called for the inner state machine cd_sp as if it's a standalone definition, so either ; or x would be considered invalid for it and I used the local error syntax with outer state machine name, like this (note main in cd_sp).

machine cdxy;

action bad_cd {prn("bad_cd", b, p);}
action bad_cd_sp {prn("bad_cd_sp", b, p);}
action cd_val {prn("cd_val", b, p);}
action my_xy_l {prn("my_xy_l", b, p);}

cd_sp = [cd ]+ %(cd_val) $lerr(main, bad_cd);

main := 
    ( cd_sp ( ";" cd_sp)* ) $lerr(bad_cd_sp)
    :>> "xy" %(my_xy_l);

, which generated a state machine I originally expected:

The docs have a sentence about sub-definitions, but just say that it is considered useful and provide no additional detail or examples. So, the question is whether this is how one would handle local errors in inner state machines or there is a more appropriate approach for this.

Thanks