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Update the CHANGELOG for SE-0324: pointer arguments to C functions #39641

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Oct 8, 2021
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Update the CHANGELOG for SE-0324: pointer arguments to C functions #39641

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26 changes: 26 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -6,6 +6,31 @@ _**Note:** This is in reverse chronological order, so newer entries are added to
Swift 5.6
---------

* [SE-0324][]:

Relax diagnostics for pointer arguments to C functions. The Swift
compiler now accepts limited pointer type mismatches when directly
calling functions imported from C as long as the C language allows
those pointer types to alias. Consequently, any Swift
`Unsafe[Mutable]Pointer<T>` or `Unsafe[Mutable]RawPointer` may be
passed to C function arguments declared as `[signed|unsigned] char
*`. Swift `Unsafe[Mutable]Pointer<T>` can also be passed to C
function arguments with an integer type that differs from `T` only
in its signedness.

For example, after importing a C function declaration:
```c
long long decode_int64(const char *ptr_to_int64);
```
Swift can now directly pass a raw pointer as the function argument:
```swift
func decodeAsInt64(data: Data) -> Int64 {
data.withUnsafeBytes { (bytes: UnsafeRawBufferPointer) in
decode_int64(bytes.baseAddress!)
}
}
```

* [SE-0315][]:

Type expressions and annotations can now include "type placeholders" which
Expand Down Expand Up @@ -8697,6 +8722,7 @@ Swift 1.0
[SE-0313]: <https://github.com/apple/swift-evolution/blob/main/proposals/0313-actor-isolation-control.md>
[SE-0315]: <https://github.com/apple/swift-evolution/blob/main/proposals/0315-placeholder-types.md>
[SE-0316]: <https://github.com/apple/swift-evolution/blob/main/proposals/0316-global-actors.md>
[SE-0324]: <https://github.com/apple/swift-evolution/blob/main/proposals/0324-c-lang-pointer-arg-conversion.md>

[SR-75]: <https://bugs.swift.org/browse/SR-75>
[SR-106]: <https://bugs.swift.org/browse/SR-106>
Expand Down