It's ok to drop the global-actor qualifier `@G` from a function's type if:
- the cast is happening in a context isolated to global-actor `G`
- the function value will not be `@Sendable`
- the function value is not `async`
It's primarily safe to drop the attribute because we're already in the
same isolation domain. So it's OK to simply drop the global-actor
if we prevent the value from later leaving that isolation domain.
This means we no longer need to warn about code like this:
```
@MainActor func doIt(_ x: [Int], _ f: @MainActor (Int) -> ()) {
x.forEach(f)
// warning: converting function value of type '@MainActor (Int) -> ()' to '(Int) throws -> Void' loses global actor 'MainActor'
}
```
NOTE: this implementation is a bit gross in that the constraint solver
might emit false warnings about casts it introduced that are actually
safe. This is mainly because closure isolation is only fully determined
after constraint solving. See the FIXME's for more details.
resolves rdar://94462333
In some situations `getContextualType` for a contextual type
locator is going to return then empty type. This happens because
e.g. optional-some patterns and patterns with incorrect type don't
have a contextual type for initialization expression but use
a conversion with contextual locator nevertheless to indicate
the purpose. This doesn't affect non-ambiguity diagnostics
because mismatches carry both `from` and `to` types.
Resolves: rdar://problem/103739206
rather than relying on PackElementExprs collected by preCheck.
This handles pack element expressions and pack element type reprs, and enforces that
all packs expanded by a given pack expansion expression all have the same shape.
Once the parser creates PackExpansionExpr directly (based on a dedicated syntax instead
of postfix '...'), the code in preCheck for identifying and creating pack expansions
can simply be deleted.
of assigning it to std::function_ref.
std::function_ref does not own the function reference, so assigning an OpenPackElementType
to a local function_ref lead to stale constraint system references when invoking
operator () later on.
Enable type checking support for explicitly specifying generic arguments to
a macro, e.g., `#stringify<Double>(1 + 2)`. To do so, introduce a new
kind of constraint that performs explicit argument matching against the
generic parameters of a macro only after the overload is chosen.
`getValue` -> `value`
`getValueOr` -> `value_or`
`hasValue` -> `has_value`
`map` -> `transform`
The old API will be deprecated in the rebranch.
To avoid merge conflicts, use the new API already in the main branch.
rdar://102362022
Rather than lookup up the macro by name again during constraint
application, use the overload choice for the macro as recorded in the
constraint system to apply the correct macro.
Replace the use of bool and pointer returns for
`walkToXXXPre`/`walkToXXXPost`, and instead use
explicit actions such as `Action::Continue(E)`,
`Action::SkipChildren(E)`, and `Action::Stop()`.
There are also conditional variants, e.g
`Action::SkipChildrenIf`, `Action::VisitChildrenIf`,
and `Action::StopIf`.
There is still more work that can be done here, in
particular:
- SourceEntityWalker still needs to be migrated.
- Some uses of `return false` in pre-visitation
methods can likely now be replaced by
`Action::Stop`.
- We still use bool and pointer returns internally
within the ASTWalker traversal, which could likely
be improved.
But I'm leaving those as future work for now as
this patch is already large enough.
function body, map the result builder type into context.
This was already done for inferred result builder attributes; now,
the constraint system will map the builder type into context for all
result builder attributes applied to computed properties/functions.
We intended to introduce AST conversions that strip concurrency
attributes off of types associated with `@preconcurrency` decls.
But for VarDecl references, we stripped it too early, leading to
things like a MemberVarDecl that doesn't have `@Sendable` in its
result type, but the VarDecl it refers to does have it.
That caused crashes in SIL where types didn't match up. This patch
fixes things by delaying the stripping until the right point.
resolves rdar://98018067
If `buildBlock` is also unavailable, or the
builder itself is unavailable, continue to solve
using `buildPartialBlock` to get better
diagnostics.
This behavior technically differs from what is
specified in SE-0348, but only affects the invalid
case where no builder methods are available to use.
In particular, this improves diagnostics for
RegexComponentBuilder when the deployment target
is too low. Previously we would try to solve using
`buildBlock` (as `buildPartialBlock` is unavailable),
but RegexComponentBuilder only defines `buildBlock`
for the empty body case, leading to unhelpful
diagnostics that ultimately preferred not to use
the result builder at all.
rdar://97533700
Previously we would cache the result of the first
query, with any further query of
`ResultBuilder::supports` ignoring the
`checkAvailability` parameter. Separate out the
availability checking such that we compute the
information up front, and adjust the result
depending on `checkAvailability`.
An extraneous argument doesn't have a corresponding parameter so the
information object for such an argument is not safe to produce.
Resolves: https://github.com/apple/swift/issues/60436
Resolves: rdar://98304482
In some circumstances opened type might not have a fixed binding.
A good example could be dependent sub-component produced for
result builder transformed code (connected via one-way constraints),
in such a case `OpenedTypes` would have outer generic parameters
but they might not be bound yet, so they have to be printed as
type variables.
