// Flat-imported generic struct with a genuinely-undeclared field type
// (`y: Missing`). 0759 covers a NON-generic imported struct; a generic one is
// instantiated cross-module, so before the fix its field nodes were resolved in
// the (main-file) instantiation context — the source-aware leaf saw "main",
// trusted it to the `UnknownTypeChecker` (which never walks imports), and
// silently fabricated a 0-field stub. `instantiateGenericStruct` now resolves
// the template's fields in THIS module's source context, so the undeclared name
// surfaces at the reference.
Bad :: struct($T: Type) {
    x: T;
    y: Missing;
}