tree e4801f1921f7b13f7b8649d9ad342f632a617e57
parent 146790992111dbd9507cdc0cc6ba8457551484e9
author Erik Ernst <eernst@google.com> 1530615350 +0000
committer Erik Ernst <eernst@google.com> 1530615350 +0000

Adjusted circularity prevention rule for type variable subtyping

We noted in issue https://github.com/dart-lang/sdk/issues/33709 that
the language specification prevents usage of `Null` as the bound
of a type variable, because that makes the bound a subtype of
the type variable itself (which is otherwise a symptom of having
a cyclic declaration like `X extends X`).

This CL adjusts the wording such that it will be possible to use
`Null` (or whatever the denoteable bottom type is called) as a
bound.

Change-Id: I46a5ce6055f3af322a6b93ac38ca2829ce23a26c
Reviewed-on: https://dart-review.googlesource.com/63420
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>