Core snapshots should be agnostic to the sound null safety mode
(so they can be used both in weak and strong modes), and snapshot
writer verifies that.
Snapshot::kFull was previously used both for core snapshots and
app snapshots on ia32. However, app snapshots are not guaranteed to
be agnostic, which appeared as failures on a few test on ia32.
Also, VM should be able to detect null safety mode from app snapshots,
even if they do not contain code, but null safety mode was not
written into features string of kFull snapshots.
In order to disambiguate core snapshots, a new Snapshot::Kind is
added. Snapshot::kFullCore works exactly as Snapshot::kFull, except
for verification of agnostic null safety and snapshot features string
omitting null safety mode. All snapshots except kFullCore now have
null safety mode included into their features string.
Fixes https://github.com/dart-lang/sdk/issues/43626
Issue https://github.com/dart-lang/sdk/issues/43613
Change-Id: I8cd3b049ef4e428dd5e1ce666d4c7aa3b596d70c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166308
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Alexander Markov
d77fff7307