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.
Introduce the compiler directive `#_hasSymbol` which will be used to detect whether weakly linked symbols are present at runtime. It is intended for use in combination with `@_weakLinked import` or `-weak-link-at-target`.
```
if #_hasSymbol(foo(_:)) {
foo(42)
}
```
Parsing only; SILGen is coming in a later commit.
Resolves rdar://99342017
In cases like `.<name>(_)`, the `_` sub-pattern should not assume
locator of the parent paren, just like it doesn't in case of tuple
i.e. `.<name>(_, ...)` where each element gets a `PatternMatch(<elt>)`
locator.
`_` pattern doesn't have a type, it's always contextual, so let's
allow it to assume a type of initializer expression instead of
creating a new type variable. This helps to makes sure that initializer
would never get a placeholder type from `_` pattern it's associated
with.
In cases like `case .test(_)` it might not be possible to
establish a type of `_` and hole cannot be propagated to
it from context if condition of switch is incorrect, so
`_` just like a named pattern should be allowed to become
a hole.
Resolves: rdar://96997534
Instead of failing constraint generation by returning `nullptr` for an `ErrorExpr` or returning a null type when a type fails to be resolved, return a fresh type variable. This allows the constraint solver to continue further and produce more meaningful diagnostics.
Most importantly, it allows us to produce a solution where previously constraint generation for a syntactic element had failed, which is required to type check multi-statement closures in result builders inside the constraint system.
Emulate previous `for-in` type-checking behavior where sequence
was type-checked separately from `.next()` call which, in turn,
was injected only during SIL generation.
Current approach to generate an implicit variable for `$generator`
and use it as a base to `.next()` call didn't account for the fact
that it allows the solver to rank result of `<sequence>.makeIterator()`
together with result of `next()`. This is logically incorrect because
`<sequence>.makeIterator()` represents initializer of `$generator`
which is separate from `$generator.next()` expression albeit type-checked
together.
Resolves: https://github.com/apple/swift/issues/59522
Don't so would disconnect $generator from `.next()` call which
have to be solved together because they sometimes depend on the
for-in pattern to infer the element type.
Instead of asking SILGen to build calls to `makeIterator` and
`$generator.next()`, let's synthesize and type-check them
together with the rest of for-in preamble. This greatly simplifies
interaction between Sema and SILGen for for-in statements.
Previously for-in target was actually an expression target, which means
certain type-checking behavior. These changes make it a standalone target
with custom behavior which would allow solver to introduce implicit
`makeIterator` and `next` calls and move some logic from SILGen.
During normal type-checking we ignore functions that contain an error. During code completion, we want to consider them and replace all error types by placeholders so we can match up the known types.
We already do this for member types (see `getTypeOfMemberReference`). We should also do it for top-level functions.
Fixes rdar://81425383 [SR-14992]
This flag biases the overload checker in favor of selecting an
asynchronous main function over a synchronous main. If no asynchronous
main function exists, a synchronous one will still be selected.
Likewise, if the flag is not passed and there are only asynchronous main
functions available, the most specific asynchronous main function will
still be selected.
Implicit casts are allowed to be constructed with a type, instead
of a type repr. Constraint generation should honor that, and fallback
to using cast type when repr is was not given.
Referencing a member in pattern context is not a regular member reference,
it should use only enum element declarations, just like leading-dot syntax
does, so both locators should end with `pattern matching` element to indicate
that to the member lookup.
Resolves: rdar://90347159
This hooks up call argument position completion to the typeCheckForCodeCompletion API to generate completions from all the solutions the constraint solver produces (even those requiring fixes), rather than relying on a single solution being applied to the AST (if any).
Co-authored-by: Nathan Hawes <nathan.john.hawes@gmail.com>
This is going to be used by multi-statement closure inference
because patterns could be declarated and referenced in the body
via the associated declaration.
Applies swift-experimental-string-processing#68 in regex literal type inference. Regex literals with captures will have type `Regex<Tuple{n}<Substring, {Captures...}>>`. This is a temporary thing that allows us to define generic constraints on captures. We will switch back to native tuples once we have variadic generics.
Opaque opaque types and record them within the "opened types" of the
constraint system, then use that information to compute the set of
substitutions needed for the opaque type declaration using the normal
mechanism of the constraint solver. Record these substitutions within
the underlying-to-opaque conversion.
Use the recorded substitutions in the underlying-to-opaque conversion
to set the underlying substitutions for the opaque type declaration
itself, rather than reconstructing the substitutions in an ad hoc manner
that does not account for structural opaque result types.
