Broken Completion Context Calculation

[cdietrich]

we have another case where the completion context calculation is broken

here is the grammar

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

Struct:
    "struct" name=ID  '{' 
        (data=ID (Fields)*)
    '}';

fragment Fields*:
    "fields" content+=FieldShorthand (',' content+=FieldShorthand)+;

FieldShorthand infers MappedField:
    FieldPartOfMappedField;

fragment FieldPartOfMappedField*:
     field=Expression;
 
Expression:
    DotExpression;

DotExpression infers Expression:
    Primary ({infer DotExpression.base=current} '.' target=DotTarget)*;

Primary infers Expression:
    {infer Parenthesis} '(' expr=Expression ')' |
    RefExpression |
    IdRef;

IdRef:
    {infer IdRef} "id";

RefExpression: ref=[Person:ID];

Person:
    'person' name=ID;

DotTarget: name=ID;

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

hidden terminal WS: /\s+/;
terminal ID: /[_a-zA-Z][\w_]*/;
terminal INT returns number: /[0-9]+/;
terminal STRING: /"(\\.|[^"\\])*"|'(\\.|[^'\\])*'/;

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

and the sample model

person A
person B

struct x {
    xxx
    fields A, |
}

the context is Struct and not MappedField.

pot.workaround

fragment Fields*:
    "fields" content+=FieldShorthand1 ( content+=FieldShorthand2)+;

FieldShorthand1 infers MappedField:
    field=Expression;

FieldShorthand2 infers MappedField:
    ',' field=Expression;