swift
[4.2][stdlib] Make sure _SwiftNewtypeWrapper hashes the same way as its RawValue
#15991
Merged
Merged
[4.2][stdlib] Make sure _SwiftNewtypeWrapper hashes the same way as its RawValue #15991
swift-ci
merged
1 commit into
swiftlang:swift-4.2-branch
from
lorentey:newtype-vs-anyhashable-4.2
[4.2][stdlib] Make sure _SwiftNewtypeWrapper hashes the same way as iā¦
95695910
lorentey7 years ago
@swift-ci please smoke test
lorentey7 years ago
@DougGregor could you take a quick look? Note that I had to add the new Self: Hashable constraint on the extension; otherwise the _hash(into:) definition clashed with its default implementation.
airspeedswift
approved these changes
on 2018-04-17
airspeedswift7 years ago
LGTM. Can you add a test for the issue it resolves?
lorentey7 years agoš 1
@airspeedswift PR #15939 includes an update to the test suite's checkHashable to also verify hash(into:) equivalency (among other things). This update will extend the scope of an existing test so that it will cover this issue. I expect to land that very soon.
lorentey7 years ago
@swift-ci please test and merge
Login to write a write a comment.
_SwiftNewtypeWrapperforwarded hashValue to its rawValue, but it failed to do the same for_hash(into:), which resulted in the wrapper struct having subtly different hashing than the raw value.This violated an implicit invariant when dictionaries/sets of such types were bridged to Objective-C through
AnyHashable, leading to nondeterministic but frequent crashes.rdar://problem/39398060
(cherry picked from commit 6c5a6a6)