A for-of loop over an array whose own facts show a hole or a stored
undefined binds T | undefined, and the typed parameters, locals, record
fields and Math arguments it reaches widen to hold it. Loops over arrays
the element-state analysis proves free of holes read each element
directly, without a per-element state test.
Object literals built from a missing-element read keep the property as
undefined in shorthand and long form, through spreads, nested records,
arrays of records, annotated locals and literal arguments to typed
parameters.
- Preserve callback identity, receiver binding, and class references across unions and collections.
- Track record field presence independently of undefined values and improve native runtime behavior.
- Expand differential coverage and streamline CI bootstrap and compiler rebuild checks.
- Compile record predicates and class guards over array-derived values.
- Preserve missing-value checks and report unsupported union refinements.
- Cover narrowing in differential tests, coverage analysis, and frontend baselines.
Fixes#477
Co-authored-by: Gianluca Esposito <735227+gesposito@users.noreply.github.com>
Chris Tate