infer on rule vs inside rule to introduce triangle type structure

[cdietrich]

given the grammar

grammar HelloWorld

entry SomeRule infers SomeParent:
    (optional?='optional')? parameterName=ID ({infer ChildA} ':' someProp=ID | {infer ChildB}'=' OtherProp=ID);


hidden terminal WS: /\s+/;
terminal ID: /[_a-zA-Z][\w_]*/;

hidden terminal ML_COMMENT: /\/\*[\s\S]*?\*\//;
hidden terminal SL_COMMENT: /\/\/[^\n\r]*/;

optional x = a

parses into

{
$type: "ChildB", 
OtherProp: "a", 
optional: false
}

but i expect

{
$type: "ChildB", 
OtherProp: "a", 
optional: true,
parameterName: "x"
}

is this a bug? or a bad usage?

[msujew]

Currently, it's a feature, but you could call it a bug as well. Calling an unassigned action just replaces the current AST node with a new one, deleting all properties. We should probably adjust that...

[spoenemann]

Yes just changing the $type should work?

[cdietrich]

solved in langium 3.1