Currently, this is staged in as `_forget`,
as part of SE-390. It can only be used on
`self` for a move-only type within a consuming
method or accessor. There are other rules, see
Sema for the details.
A `forget self` really just consumes self and
performs memberwise destruction of its data.
Thus, the current expansion of this statement
just reuses what we inject into the end of a
deinit.
Parsing of `forget` is "contextual".
By contextual I mean that we do lookahead to
the next token and see if it's identifier-like.
If so, then we parse it as the `forget` statement.
Otherwise, we parse it as though "forget" is an
identifier as part of some expression.
This way, we won't introduce a source break for
people who wrote code that calls a forget
function.
This should make it seamless to change it from
`_forget` to `forget` in the future.
resolves rdar://105795731
Provide ASTWalker with a customization point to specify whether to
check macro arguments (which are type checked but never emitted), the
macro expansion (which is the result of applying the macro and is
actually emitted into the source), or both. Provide answers for the
~115 different ASTWalker visitors throughout the code base.
Fixes rdar://104042945, which concerns checking of effects in
macro arguments---which we shouldn't do.
This lets us consolidate code paths that mostly run in parallel over the
existing InOutTypeRepr/SharedTypeRepr/OwnedTypeRepr family of types. This
patch by itself is NFC but makes it easier to introduce new spellings,
particularly the newly-official `borrowing` and `consuming` modifiers
that were approved in SE-0377.
Various requests expect to be walking over the current source file.
While we could add checks to all these to skip decls outside of the
current buffer, it's a little nicer to handle this during the walk
instead.
Allow ignoring nodes that are from macro expansions and add that flag to
the various walks that expect it.
Also add a new `getOriginalAttrs` that filters out attributes in
generated source.
Introduce SingleValueStmtExpr, which allows the
embedding of a statement in an expression context.
This then allows us to parse and type-check `if`
and `switch` statements as expressions, gated
behind the `IfSwitchExpression` experimental
feature for now. In the future,
SingleValueStmtExpr could also be used for e.g
`do` expressions.
For now, only single expression branches are
supported for producing a value from an
`if`/`switch` expression, and each branch is
type-checked independently. A multi-statement
branch may only appear if it ends with a `throw`,
and it may not `break`, `continue`, or `return`.
The placement of `if`/`switch` expressions is also
currently limited by a syntactic use diagnostic.
Currently they're only allowed in bindings,
assignments, throws, and returns. But this could
be lifted in the future if desired.
This is needed for general fidelity in SIL, since generic argument
lists are used for a lot of different things that aren't restricted
from containing multiple packs. I haven't actually done the work to
use Pack structure to disambiguate the resolution of pack parameters,
but this is a good start.
We'll probably need something like this in source eventually, so
there's no reason to regret adding all the infrastructure for it.
Add support for freestanding declaration macros.
- Parse `@declaration` attribute.
- Type check and expand `MacroExpansionDecl`.
Known issues:
- Generic macros are not yet handled.
- Expansion does not work when the parent decl context is `BraceStmt`. Need to parse freestanding declaration macro expansions in `BraceStmt` as `MacroExpansionDecl`, and add expanded decls to name lookup.
pack expansion type reprs.
Classic variadic parameters still use the postfix ellipsis syntax, and
pack expansion types now use a prefix 'repeat' keyword.
Although the declaration of macros doesn't appear in Swift source code
that uses macros, they still operate as declarations within the
language. Rework `Macro` as `MacroDecl`, a generic value declaration,
which appropriate models its place in the language.
The vast majority of this change is in extending all of the various
switches on declaration kinds to account for macros.
Introduce `MacroExpansionExpr` and `MacroExpansionDecl` and plumb it through. Parse them in roughly the same way we parse `ObjectLiteralExpr`.
The syntax is gated under `-enable-experimental-feature Macros`.
Semantically, the capture list binding behavior doesn't require the scope
to be an explicit closure, and forming new ClosureExprs during type-checking
is difficult because they have to have preassigned discriminators, unlike
AutoClosureExprs which get discriminators introduced by Sema itself. Allowing
CaptureListExpr to hold an AutoClosureExpr makes it easier to synthesize
CaptureListExprs during type checking, to represent expressions with closure
semantics that evaluate some parts of the expression eagerly in the surrounding
context.
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
Allow ASTWalker subclasses to specify whether
they want to visit lazy variable initializers as
part of the pattern binding, getter body, or not
at all.
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.
Represent this in much the same way that collections do by creating an opaque value representing the source argument, and a conversion expression representing the destination argument.
Pack expressions take a series of argument values and bundle them together as a pack - much like how a tuple expression bundles argument expressions into a tuple.
Pack reification represents the operation that converts packs to tuples/scalar types in the AST. This is important since we want pack types in return positions to resolve to tuples contextually.
