Offsets lower to GetElementPointer inbounds, which specifies that it's
Undefined Behaviour for the result to be out of bounds, regardless of if
the result is actually dereferenced.
SE-0107 states that UnsafePointer.withMemoryRebound(to:capacity:) should produce
a const UnsafePointer, but the implementation that I committed in Whitney
produces an UnsafeMutablePointer.
As a result Swift 3 accepts code, that we would like to reject:
func takesUInt(_: UnsafeMutablePointer<UInt>) {}
func takesConstUInt(_: UnsafePointer<UInt>) {}
func foo(p: UnsafePointer<Int>) {
p.withMemoryRebound(to: UInt.self, capacity: 1) {
takesUInt($0) // <========= implicitly converts to a mutable pointer
takesConstUInt($0)
}
}
We would like to reject this in favor of:
func takesUInt(_: UnsafeMutablePointer<UInt>) {}
func takesConstUInt(_: UnsafePointer<UInt>) {}
func foo(p: UnsafePointer<Int>) {
p.withMemoryRebound(to: UInt.self, capacity: 1) {
takesUInt(UnsafeMutablePointer(mutating: $0))
takesConstUInt($0)
}
}
This looks to me like an experimental change accidentally creeped onto my branch
and it was hard to spot in .gyb code. I needed to write the unit test
in terms of UnsafeMutablePointer in order to use expectType, so didn't
catch this.
rdar://28409842 UnsafePointer.withMemoryRebound(to:capacity:) incorrectly produces a mutable pointer argument
Those builtins are: allocWithTailElems_<n>, getTailAddr and projectTailElems
Also rename the "gep" builtin, which indexes raw bytes, to "gepRaw" and add a new "gep" builtin to index in a typed array.
Those builtins are: allocWithTailElems_<n>, getTailAddr and projectTailElems
Also rename the "gep" builtin, which indexes raw bytes, to "gepRaw" and add a new "gep" builtin to index in a typed array.
This introduces some important diagnostics to help migration.
Some of the diagnostics that we would like to provide are impossible
on a generic class because they introduce ambiguity.
Renaming UnsafePointer<Void> to UnsafeRawPointer makes extensions and
global operators ambiguous.
We would also like to provide this fix-it on conversion from
UnsafePointer<Void> or UnsafeRawPointer to UnsafePointer<T>
with this message:
Conversion restricted. Use 'assumingMemoryBound(to:)' or 'bindMemory(to:capacity:)'}}
However, that introduces ambiguous overloads that defeat other hueristics.
As of now:
* old APIs are just marked as `deprecated` not `unavaiable`. To make it
easier to co-operate with other toolchain repos.
* Value variant of API is implemented as public @private
`_ofInstance(_:)`.
Update for SE-0107: UnsafeRawPointer
This adds a "mutating" initialize to UnsafePointer to make
Immutable -> Mutable conversions explicit.
These are quick fixes to stdlib, overlays, and test cases that are necessary
in order to remove arbitrary UnsafePointer conversions.
Many cases can be expressed better up by reworking the surrounding
code, but we first need a working starting point.
This is another necessary step in introducing changes
for SE-0107: UnsafeRawPointer.
UnsafeRawPointer is great for bytewise pointer operations.
OpaquePointer goes away.
The _RawByte type goes away.
StringBuffer always binds memory to the correct CodeUnit
when allocating memory.
Before accessing the string, a dynamic element width check
allows us to assume the bound memory type.
Generic entry points like atomicCompareExchange no longer handle
both kinds of pointers. Normally that's good because you
should not be using generics in that case, just upcast
to raw pointer. However, with pointers-to-pointers
you can't do that.
The reverts part of my previous patch. Removing the operators is too much of a
performance penalty to take. The difference is that the Strideable operators are
not transparent.
I still need to remove the UnsafeRawPointer operators, so -Onone performance
will be bad in some cases until this is fixed:
<rdar://problem/27513184> [perf] Strideable operators are not transparent. This is a huge -Onone performance penalty.
Generic versions of these functions are provided by Strideable.
This is required for SE-0107: UnsafeRawPointer. Otherwise, the presence
of non-generic operator overloads will conflict with existing operators
on String.
* Add UnsafeRawPointer type and API.
As proposed in SE-0107: UnsafeRawPointer.
https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md
The fundamental difference between Unsafe[Mutable]RawPointer and
Unsafe[Mutable]Pointer<Pointee> is simply that the former is used for "untyped"
memory access, and the later is used for "typed" memory access. Let's refer to
these as "raw pointers" and "typed pointers". Because operations on raw pointers
access untyped memory, the compiler cannot make assumptions about the underlying
type of memory and must be conservative. With operations on typed pointers, the
compiler may make strict assumptions about the type of the underlying memory,
which allows more aggressive optimization.
Memory can only be accessed by a typed pointer when it is currently
bound to the Pointee type. Memory can be bound to type `T` via:
- `UnsafePointer<T>.allocate(capacity: n)`
- `UnsafePointer<Pointee>.withMemoryRebound(to: T.self, capacity: n) {...}`
- `UnsafeMutableRawPointer.initializeMemory(as: T.self, at: i, count: n, to: x)`
- `UnsafeMutableRawPointer.initializeMemory(as: T.self, from: p, count: n)`
- `UnsafeMutableRawPointer.moveInitializeMemory(as: T.self, from: p, count: n)`
- `UnsafeMutableRawPointer.bindMemory(to: T.self, capacity: n)`
Mangle UnsafeRawPointer as predefined substitution 'Sv' for Swift void
pointer ([urp] are taken).
* UnsafeRawPointer minor improvements.
Incorporate Dmitri's feedback.
Properly use a _memmove helper.
Add load/storeBytes alignment precondition checks.
Reword comments.
Demangler tests.
* Fix name mangling test cases.
* Fix bind_memory specialization.
As proposed in SE-0107: UnsafeRawPointer:
Rename 'init(allocatingCapacity:)' to 'UnsafeMutablePointer.allocate(capacity:)'
Rename 'deallocateCapacity' to 'deallocate(capacity:)'
`allocate` should not be an initializer. It's primary function is to allocate
memory, not initialize a pointer.
Added tests for expected-error and fix-its.
- Add arguments signature regardless that is the same as before.
Because the error message looks more natural.
e.g. "makeIterator" => "makeIterator()",
"replaceSubrange" => "replaceSubrange(_:with:)"
- Any${ExistentialCollection}.underestimateCount() was a method, not
computed property.
- 'LazySequenceType' has been renamed to 'LazySequenceProtocol', but not
'LazyCollectionProtocol'
- Streamable.writeTo(_:) had no argument label.
- Fixed typo in print() debugPrint() error message (not working for now)
- Repeated.init(): changed `renamed` to `message` because the arugment
order has changed.
- Marked `public` for some unavailable method on `Sequence`
- Sequence.split(_:maxSplit:allowEmptySlices) was replaced with
split(separator:maxSplits:omittingEmptySubsequences:),
not split(separator:omittingEmptySubsequences:isSeparator:)
- Sequence.split(_:allowEmptySlices:isSeparator) was replaced with
split(maxSplits:omittingEmptySubsequences:isSeparator:),
not split(_:omittingEmptySubsequences:isSeparator:)
- Sequence.startsWith(_:isEquivalent:) or startsWith(_:) had no label on
the first argument.
- transcode(_:_:_:_:stopOnError), not transcode(_:_:_:_:stoppingOnError)
- Removed mutating methods from UnsafePointer.
alloc(_:), dealloc(_:), setter:memory, initialize(_:), destroy(),
and destroy(_:)
This removes a `FIXME` comment between the documentation for `UnsafeMutablePointer.initialize(with:count:)` that is preventing the documentation from attaching to the symbol.
Implements SE-0055: https://github.com/apple/swift-evolution/blob/master/proposals/0055-optional-unsafe-pointers.md
- Add NULL as an extra inhabitant of Builtin.RawPointer (currently
hardcoded to 0 rather than being target-dependent).
- Import non-object pointers as Optional/IUO when nullable/null_unspecified
(like everything else).
- Change the type checker's *-to-pointer conversions to handle a layer of
optional.
- Use 'AutoreleasingUnsafeMutablePointer<NSError?>?' as the type of error
parameters exported to Objective-C.
- Drop NilLiteralConvertible conformance for all pointer types.
- Update the standard library and then all the tests.
I've decided to leave this commit only updating existing tests; any new
tests will come in the following commits. (That may mean some additional
implementation work to follow.)
The other major piece that's missing here is migration. I'm hoping we get
a lot of that with Swift 1.1's work for optional object references, but
I still need to investigate.
This is a staging attribute that will eventually mean "fixed-contents"
for structs and "closed" for enums, as described in
docs/LibraryEvolution.rst.
This is pretty much the minimal set of types that must be fixed-layout,
because SILGen makes assumptions about their lowering.
If desired, some SILGen refactoring can allow some of these to be
resilient. For example, bridging value types could be made to work
with resilient types.
