Avoid describing the exact algorithm that these collections use to allocate storage. (It is a private implementation detail that we want to be able to change.)
rdar://problem/36619317
When a duplicate key is found during rehashing, it is usually either because a key was mutated after insertion, or because the dictionary itself was mutated from multiple threads at the same time.
Both of these are serious programmer errors. Promote the sanity check for duplicate keys to a full precondition and improve the error message to point out the most probable cause of the failure.
When implementing a protocol requirement, additional doc comments are
unnecessary unless there are additional semantics peculiar to the specific
implementation.
The manually propagated documentation had several problems, including copypasta
and inconsistent terminology.
Therefore, if `T.==` doesn't have any doc comments and the implementation of
`T.hashValue` is unremarkable, remove the unnecessary doc comment.
This assumes these will land in Swift 4.1; the attributes need to be adjusted if that turns out not to be the case.
It seems @available for protocol conformances is not yet functional. I added attributes for those anyway, marked with FIXME(conformance-availability).
# Conflicts:
# stdlib/public/core/ExistentialCollection.swift.gyb
# stdlib/public/core/Mirror.swift
* Add conditional Hashable conformance to Optional, Dictionary, Array, ArraySlice and ContiguousArray
* Modified hashValue implementations
The hashValues are now calculated similar to the automatically synthesized values when conforming to Hashable.
This entails using _combineHashValues as values of the collections are iterated - as well as calling _mixInt before returning the hash.
* Added FIXMEs as suggested by Max Moiseev
* Use checkHashable to check Hashable conformance
* Use 2 space indentation
* Hashing of Dictionary is now independent of traversal order
* Added a test to proof failure of (previous) wrong implementation of Dictionary hashValue. Unfortunately it does not work.
* Removed '_mixInt' from 'hashValue' implementation of Optional and Array types based on recommendations from lorentey
* Another attempt at detecting bad hashing due to traversal order
* Dictionary Hashable validation tests now detect bad hashing due to dependence on traversal order
* Removed superfluous initial _mixInt call for Dictionary hashValue implementation.
* Add more elements to dictionary in test to increase the number of possible permutations - making it more likely to detect order-dependent hashes
* Added Hashable conformance to CollectionOfOne, EmptyCollection and Range types
* Fix indirect referral to the only member of CollectionOfOne
* Re-added Hashable conformance to Range after merge from master
* Change hashValue based on comment from @lorentey
* Remove tests for conditional Hashable conformance for Range types. This is left for a followup PR
* Added tests for CollectionOfOne and EmptyCollection
* Added conditional conformance fo Equatable and Hashable for DictionaryLiteral. Added tests too.
* Added conditional Equatable and Hashable conformance to Slice
* Use 'elementsEqual' for Slice equality operator
* Fixed documentation comment and indentation
* Fix DictionaryLiteral equality implementation
* Revert "Fix DictionaryLiteral equality implementation"
This reverts commit 7fc1510bc3.
* Fix DictionaryLiteral equality implementation
* Use equalElements(:by:) to compare DictionaryLiteral elements
* Added conditional conformance for Equatable and Hashable to AnyCollection
* Revert "Use 'elementsEqual' for Slice equality operator"
This reverts commit 0ba2278b96.
* Revert "Added conditional Equatable and Hashable conformance to Slice"
This reverts commit 84f9934bb4.
* Added conditional conformance for Equatable and Hashable for ClosedRange
Split HashedCollections.swift.gyb into separate Set.swift and Dictionary.swift files, with some common parts going into Hashing.swift.
This is mostly a mechanical change, in preparation of unification of common parts between Set & Dictionary.
rdar://problem/34038727
