fragment block gets in the way of completion provider?

[antoinelilly]

Good morning!

I came across a behavior that seems inherent to the way Langium builds contexts for completion whether the keyword follows a fragment block or not. I was able to reproduce my issue using the playground example, I will post images below.

Here is the kind of grammar I was using :

entry Model: (persons+=Person | greetings+=Greeting)*;

fragment OptionBlock: (abstract?='abstract')?;

Person: OptionBlock 'person' name=ID;
Greeting:  'Hello' person=[Person:ID] '!';

But whenever I tried to use autocompletion, only the keywords 'abstract' and 'Hello' were visible, even though I expected 'person' to be available as well. I looked into it for a while, then I tried the following grammar:

entry Model: (persons+=Person | greetings+=Greeting)*;

Person: (abstract?='abstract')?'person' name=ID;
Greeting:  'Hello' person=[Person:ID] '!';

which I expected to be exactly equivalent to the previous one, but then all keywords ('person', 'abstract' and 'Hello') were visible. Is this the expected behavior of a fragment block ? If not, is it possible to extend the completion provider to the keyword right after the fragment ?

Thank you !