Disallow illegal UnsafePointer conversions. (#3858)
As proposed in SE-0107: UnsafeRawPointer.
https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md
Remove the initializers that allow type inference to
change the Pointee type of an UnsafePointer.
These initializers violate the strict aliasing
aspect of the memory model and can lead to undefined
behavior.
diff --git a/stdlib/public/core/UnsafePointer.swift.gyb b/stdlib/public/core/UnsafePointer.swift.gyb
index a507bc5..8331330 100644
--- a/stdlib/public/core/UnsafePointer.swift.gyb
+++ b/stdlib/public/core/UnsafePointer.swift.gyb
@@ -77,50 +77,19 @@
self._rawValue = Builtin.inttoptr_Word(bitPattern._builtinWordValue)
}
- /// Convert from any `UnsafeMutablePointer`, possibly with a
- /// different `Pointee`.
- ///
- /// - Warning: the behavior of accesses to pointee as a type
- /// different from that to which it was initialized is undefined.
+ /// Construct ${a_Self} from another ${a_Self}.
@_transparent
- public init<U>(_ from : UnsafeMutablePointer<U>) {
- _rawValue = from._rawValue
+ public init(_ other: ${Self}<Pointee>) {
+ self = other
}
- /// Convert from any `UnsafeMutablePointer`, possibly with a
- /// different `Pointee`.
+ /// Construct ${a_Self} from another ${a_Self}.
///
- /// Returns nil if `from` is nil.
- ///
- /// - Warning: the behavior of accesses to pointee as a type
- /// different from that to which it was initialized is undefined.
+ /// Returns nil if `other` is nil.
@_transparent
- public init?<U>(_ from : UnsafeMutablePointer<U>?) {
- guard let unwrapped = from else { return nil }
- self.init(unwrapped)
- }
-
- /// Convert from any `UnsafePointer`, possibly with a
- /// different `Pointee`.
- ///
- /// - Warning: the behavior of accesses to pointee as a type
- /// different from that to which it was initialized is undefined.
- @_transparent
- public init<U>(_ from : UnsafePointer<U>) {
- _rawValue = from._rawValue
- }
-
- /// Convert from any `UnsafePointer`, possibly with a
- /// different `Pointee`.
- ///
- /// Returns nil if `from` is nil.
- ///
- /// - Warning: the behavior of accesses to pointee as a type
- /// different from that to which it was initialized is undefined.
- @_transparent
- public init?<U>(_ from : UnsafePointer<U>?) {
- guard let unwrapped = from else { return nil }
- self.init(unwrapped)
+ public init?(_ other: ${Self}<Pointee>?) {
+ guard let unwrapped = other else { return nil }
+ self = unwrapped
}
% if mutable:
@@ -140,6 +109,21 @@
guard let unwrapped = other else { return nil }
self.init(mutating: unwrapped)
}
+% else:
+ /// Convert from `UnsafeMutablePointer` to ${a_Self} of the same `Pointee`.
+ @_transparent
+ public init(_ other: UnsafeMutablePointer<Pointee>) {
+ self._rawValue = other._rawValue
+ }
+
+ /// Convert from `UnsafeMutablePointer` to ${a_Self} of the same `Pointee`.
+ ///
+ /// Returns nil if `from` is nil.
+ @_transparent
+ public init?(_ other: UnsafeMutablePointer<Pointee>?) {
+ guard let unwrapped = other else { return nil }
+ self.init(unwrapped)
+ }
% end
% if mutable:
