JS model loader doesn’t understand union type alias in ceylon.ast.core

ceylon compile-js ceylon.ast.samples ceylon.ast.core ceylon.ast.create && ceylon compile-js ceylon.ast.samples

Running this in the ceylon.ast repository on the version-1.3.1 branch, under the 1.3.1 distribution (e. g. from release or built from the 1.3.1 tag) produces 34 errors of the kind:

error: specified expression must be assignable to declared type of ‘expression’: ‘Expression&AssigningExpression’ (‘Expression’) is not assignable to ‘AssigningExpression’ (‘unknown’) error: argument must be assignable to parameter ‘operand’ of ‘NotOperation’: ‘EqualOperation’ is not assignable to ‘NegatingExpression’ (‘unknown’)

It seems the model loader isn’t loading ceylon.ast’s precedence aliases (*ingExpression). @jvasileff reports that ceylon compile-dart, which also uses the JS model loader, has the same problem.

This blocks the ceylon.ast 1.3.1 release.

[jvasileff]

I think @lucaswerkmeister’s reduction is a slightly different case where the class’s parameter’s type winds up with a bad resolvedAliases type, whereas in the original case, it was the type alias’s extended type that had a bad resolvedAliases type.

A further reduction of this second scenario is:

shared class C([ConjoiningExpression, String] children) {}
// resolved type of children becomes: [unknown, String] (type)

shared alias ConjoiningExpression => C|String;

and

import tmp {...}

void run() {
    C(["", ""]);
}

Note that this one is sensitive to ordering; renaming the alias can cause the error to disappear.

[lucaswerkmeister]

Thanks for investigating this! I managed to boil it down to a shorter example:

// module tmp
shared class UIdentifier() {
    shared void transform(Transformer t) {}
}
shared class AndOperation(children) {
    shared [ConjoiningExpression, NegatingExpression] children;
}
shared interface Transformer {
    shared formal void transformUIdentifier(UIdentifier that);
}
shared alias ConjoiningExpression => AndOperation|UIdentifier;
shared alias NegatingExpression => UIdentifier;

// module tmp2
import tmp {
    UIdentifier,
    AndOperation
}
shared void run() {
    value ui = UIdentifier();
    value ao = AndOperation([ui, ui]);
}