Resolving Cross-references works in Test but not in running editor

[tbuchmann]

Hello everybody,

I'm switching from Xtext to Langium and so far everything works fine (despite I'm still learning TypeScript). However, I ran into a strange problem where I need some help.

I want to write a small language for modeling UML class diagrams with a textual syntax.
Types (Class | Interface | Enum | DataType | PrimitiveType | Association) are contained in packages. Classes may extend other Classes (and implement Interfaces), whereas Interfaces only may extend other Interfaces. A cutout of the grammar looks like this:

type Type =
    Class | Interface | DataType | PrimitiveType | Enumeration | Association;

entry Model:
    packages+=Package*;

Package:
    'package' name=ID '{'
        (packages+=Package | types+=(Class|Interface|DataType|PrimitiveType|Enumeration|Association) )*
    '}';

Interface returns Type:
    {infer Interface} (vis=VisibilityKind)? 'interface' name=ID 
    ('extends' superInterfaces+=[Interface:ID] (',' superInterfaces+=[Interface:ID])*)? '{'
        (properties+=Property | operations+=Operation)*
    '}';

I'm facing the following problem: The following test works as expected

test('parse interface with multiple inheritance', async () => {
        document = await parse(`
            package de {
                interface A {}
                interface B {}
                interface C extends A, B {}
            }
        `);        

        expect(document.parseResult.parserErrors).toHaveLength(0);

        expect(
            checkDocumentValid(document) || s`
            Interfaces:
              ${(document.parseResult.value?.packages?.[0].types as Interface[]).map(c => c.name)?.join('\n')}
            Super-Interfaces:
              ${(document.parseResult.value?.packages?.[0].types?.[2] as Interface).superInterfaces?.map(i => i.ref?.name)?.join('\n')}
            `
        ).toBe(s`
            Interfaces:
              A
              B
              C
            Super-Interfaces:
              A
              B
        `);
    });

But when I start the extension in debugging mode and enter the same text into a new document the superInterfaces reference of interface "C" is empty.

[cdietrich]

How do you evaluate this in your extension? Refs are getters so you need to call them

[cdietrich]

Maybe you can also provide a reproducer

[tbuchmann]

I could give you access to the repository, where the code is hosted if that helps.
Steps to reproduce: Run parsing.test.ts (works)
Set breakpoint in line 146 of generator.ts
Press F5 to start extension in Debug mode, create a new file with ending .cdiag
Copy the following text to the new file:

package de {
    interface A {}
    interface B {}
    interface C extends A, B {}
}

Save the file (triggers the generator).

[cdietrich]

Yes I can have a look later today

[cdietrich]

the problem is your
checkNoCycleInInterfaceInheritance
the pops might also pop them them their original place...

[tbuchmann]

Oh, you're right. Thanks a lot for your time and help!
Guess that calls for some integration tests ;)