[SE-0458] Improvements to strict memory safety checking based on the ongoing review #2689
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The Detailed Design was becoming a grab-bag of sections, so give it more structure. First, we describe all of the sources of memory unsafety in Swift. Then, note the role of the @safe attribute. Finally, describe all of the ways in which one can acknowledge unsafety. One drive-by fix here is to document the unsafe conformances of the `UnsafeBufferPointer` family of types to the `Collection` protocol hierarchy.
…edge them This was lost in my restructuring
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| Implementing a protocol requirement that is safe (and not part of an `@unsafe` protocol) within an `@unsafe` declaration introduces unsafety, so it will produce a diagnostic in the strict safety mode: | ||
| Swift's `for..in` loops are effectively implemented as syntactic sugar over the `Sequence` and `IteratorProtocol` protocols, where the `for..in` creates a new iterator (with `Sequence.makeIterator()`) and then calls its `next()` operation for each loop iteration. If the conformances to `Sequence` are `IteratorProtocol` is `@unsafe`, the loop will introduce a warning: |
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... `Sequence` are `IteratorProtocol` is `@unsafe`, the loop will introduce a warning:
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| @@ -740,7 +824,14 @@ We could introduce an optional `message` argument to the `@unsafe` attribute, wh | |||
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| ## Revision history | |||
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| * **Revision 2 (following first review)** | |||
| * **Revision 3 (following second review eextension)** | |||
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**Revision 3 (following second review eextension)**
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This pull request improves the proposal in number of ways:
@unsafe; it is implied. They may be marked@safeto indicate that they are actually safe.unsafefor iteration via thefor..insyntax.@unsafefor C types that involve pointers.UnsafeBufferPointerfamily of types to theCollectionprotocol hierarchy.