It used `ObjectVisitor` to peak into constant objects. The visitor
called `AddConstObject` directly while keeping raw pointers around.
This is unsafe because `AddConstObject` can cause GC for several
different reasons - which would potentially invalidate those raw
pointers.
I have added `NoSafepointScope` around `VisitPointers` but this
does not actually easily reveal the bug because allocations are
really sporadic and often require to be running in PRODUCT mode
to trigger corresponding code path. Unfortunately we don't have
any existing infrastructure to catch "allocation from unsafe
place" which works across all build modes and catches even
situations where allocation can _potentially_ happen.
Fixes https://github.com/flutter/flutter/issues/153358
TEST=manually with a reproduction provided by internal user.
R=kustermann@google.com
Change-Id: I0c9e14a137b1f8ac749443d80f6904f1e9b20ed7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/382883
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
Vyacheslav Egorov
ea500b450a