Support subtyping in tail calls #4032
Merged
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The tail call spec does not include subtyping because it is based on the
upstream spec, which does not contain subtyping. However, there is no reason
that subtyping shouldn't apply to tail calls like it does for any other call or
return. Update the validator to allow subtyping and avoid a related null pointer
dereference while we're at it.
Do not run the test in with --nominal because it is buggy in that mode.