As specified by the SE-0446 acceptance, extensions that declare a type's
conditional `Copyable` or `Escapable` ability must reiterate explicitly all
of the `Copyable` and/or `Escapable` requirements, whether required or not
required (by e.g. `~Copyable`) that were suppressed in the original
type declaration.
Types annotated as `@_addressableForDependencies` are still usable by older
compilers that don't know about nonescapable types or lifetime dependencies,
since it only affects the behavior of the type when it's the source of a
dependency.
Introduce an `unsafe` expression akin to `try` and `await` that notes
that there are unsafe constructs in the expression to the right-hand
side. Extend the effects checker to also check for unsafety along with
throwing and async operations. This will result in diagnostics like
the following:
10 | func sum() -> Int {
11 | withUnsafeBufferPointer { buffer in
12 | let value = buffer[0]
| | `- note: reference to unsafe subscript 'subscript(_:)'
| |- warning: expression uses unsafe constructs but is not marked with 'unsafe'
| `- note: reference to parameter 'buffer' involves unsafe type 'UnsafeBufferPointer<Int>'
13 | tryWithP(X())
14 | return fastAdd(buffer.baseAddress, buffer.count)
These will come with a Fix-It that inserts `unsafe` into the proper
place. There's also a warning that appears when `unsafe` doesn't cover
any unsafe code, making it easier to clean up extraneous `unsafe`.
This approach requires that `@unsafe` be present on any declaration
that involves unsafe constructs within its signature. Outside of the
signature, the `unsafe` expression is used to identify unsafe code.
I need this today to add the implicit isolated parameter... but I can imagine us
adding more implicit parameters in the future, so it makes sense to formalize it
so it is easier to do in the future.
Protocol conformances have a handful attributes that can apply to them
directly, including @unchecked (for Sendable), @preconcurrency, and
@retroactive. Generalize this into an option set that we carry around,
so it's a bit easier to add them, as well as reworking the
serialization logic to deal with an arbitrary number of such options.
Use this generality to add support for @unsafe conformances, which are
needed when unsafe witnesses are used to conform to safe requirements.
Implement general support for @unsafe conformances, including
producing a single diagnostic per missing @unsafe that provides a
Fix-It and collects together all of the unsafe witnesses as notes.
`UnsafeCastExpr` - A special kind of conversion that performs an unsafe
bitcast from one type to the other.
Note that this is an unsafe operation and type-checker is allowed to
use this only in a limited number of cases like: `any Sendable` -> `Any`
conversions in some positions, covariant conversions of function and
function result types.
It replaces `DeclAttr::getUnavailable()` and `AvailableAttr::isUnavailable()`
as the designated way to query for the attribute that makes a decl unavailable.
This type is intended to be used to wrap compiler synthesized nodes
(i.e. variables) to make it easier for diagnostic to diagnose precise
failure locations.
Consider the situation like:
```
protocol P {}
extension Array: P where Element: P {}
func test<T: P>() -> T {
$_a = ...
$_b = ...
return [$_a, $_b]
}
```
This is a common pattern with result builders.
In this case if one of the elements don't conform to `P` the best
user experience would be to attach diagnostic to the element otherwise
the developers would have to figure out where in result expression
the error occured before attempting to fix it.
Fixes a bug where references to the opaque types of other decls were printed
with the `some Type` syntax, breaking the interface. Only the opaque type
introduced by a declaration should be printed with the `some Type` syntax;
other opaque types must always be printed as a stable addresses instead.
Resolves rdar://134582913.
Today ParenType is used:
1. As the type of ParenExpr
2. As the payload type of an unlabeled single
associated value enum case (and the type of
ParenPattern).
3. As the type for an `(X)` TypeRepr
For 1, this leads to some odd behavior, e.g the
type of `(5.0 * 5).squareRoot()` is `(Double)`. For
2, we should be checking the arity of the enum case
constructor parameters and the presence of
ParenPattern respectively. Eventually we ought to
consider replacing Paren/TuplePattern with a
PatternList node, similar to ArgumentList.
3 is one case where it could be argued that there's
some utility in preserving the sugar of the type
that the user wrote. However it's really not clear
to me that this is particularly desirable since a
bunch of diagnostic logic is already stripping
ParenTypes. In cases where we care about how the
type was written in source, we really ought to be
consulting the TypeRepr.
`Builtin.FixedArray<let N: Int, T: ~Copyable & ~Escapable>` has the layout of `N` elements of type `T` laid out
sequentially in memory (with the tail padding of every element occupied by the array). This provides a primitive
on which the standard library `Vector` type can be built.
Instead of doing the pattern parsing in both the
C++ parser and ASTGen, factor out the parsing into
a request that returns the pattern to emit, regex
type, and version. This can then be lazily run
during type-checking.
Lifetime dependencies will now be represented with @lifetime attribute in the language.
dependsOn is a type modifier and was represented as a LifetimeDependentTypeRepr in the AST.
I am deleting dependsOn syntax parsing support and retaining LifetimeDependentTypeRepr support.
We may want to represent lifetime dependencies in a function type with a type attribute in the future.
If we use a decl attribute instead, then support for LifetimeDependentTypeRepr can be deleted.
