Remove this bit from function decls and closures.
Instead, for closures, infer it from the presence
of a single return or single expression AST node
in the body, which ought to be equivalent, and
automatically takes result builders into
consideration. We can also completely drop this
query from AbstractFunctionDecl, replacing it
instead with a bit on ReturnStmt.
This couples together several changes to move entirely from
`@rethrows` over to typed throws:
* Use the `Failure` type to determine whether an async for-each loop
will throw, rather than depending on rethrows checking
* Introduce a special carve-out for `rethrows` functions that have a
generic requirement on an `AsyncSequence` or `AsyncIteratorProtocol`,
which uses that requirement's `Failure` type as potentially being part
of the thrown error type. This allows existing generic functions like
the following to continue to work:
func f<S: AsyncSequence>(_: S) rethrows
* Switch SIL generation for the async for-each loop from the prior
`next()` over to the typed-throws version `_nextElement`.
* Remove `@rethrows` from `AsyncSequence` and `AsyncIteratorProtocol`
entirely. We are now fully dependent on typed throws.
Avoid forming invalid source ranges when
`ReturnLoc` is invalid. Also introduce a utility
to make this kind of range computation easier,
and use it in a couple of other cases.
Previously, 'IntroducerLoc' and 'ThePattern' were only used for pattern
binidng cases. Create a new 'ConditionalPatternBindingInfo' type to
cover such cases, and make 'StmtConditionElement' a pure 'PointerUnion'
type.
This makes it clear which fields are used in which condition kind. Also,
we can expect overall size reduction of StmtCondition when the
majority of the conditions are simple boolean expressions.
Correctly determining the DeclContext needed for an
ExplicitCaughtTypeRequest is tricky for a number of callers, and
mistakes here can easily lead to redundant computation of the caught
type, redundant diagnostics, etc.
Instead, put a `DeclContext` into `DoCatchStmt`, because that's the
only catch node that needs a `DeclContext` but does not have one.
These two requests are effectively doing the same thing to two
different cases within CatchNode. Unify the requests into a single
request, ExplicitCaughtTypeRequest, which operates on a CatchNode.
This also moves the logic for closures with explicitly-specified throws
clauses into the same request, taking it out of the constraint system.
During the review of SE-0413, typed throws, the notion of a `do throws`
syntax for `do..catch` blocks came up. Implement that syntax and
semantics, as a way to explicitly specify the type of error that is
thrown from the `do` body in `do..catch` statement.
For any operation that can throw an error, such as calls, property
accesses, and non-exhaustive do..catch statements, record the thrown
error type along with the conversion from that thrown error to the
error type expected in context, as appropriate. This will prevent
later stages from having to re-compute the conversion sequences.
The type that is caught by the `catch` clauses in a `do..catch` block is
determined by the union of the thrown error types in the `do`
statement. Compute this type and use it for the catch clauses. This
does several things at once:
* Makes the type of the implicit `error` be a more-specific concrete
type when all throwing sites throw that same type
* When there's a concrete type for the error, one can use patterns
like `.cancelled`
* Check that this error type can be rethrown in the current context
* Verify that SIL generation involving do..catch with typed errors
doesn't require any existentials.
These allow multi-statement `if`/`switch` expression
branches that can produce a value at the end by
saying `then <expr>`. This is gated behind
`-enable-experimental-feature ThenStatements`
pending evolution discussion.
Reformatting everything now that we have `llvm` namespaces. I've
separated this from the main commit to help manage merge-conflicts and
for making it a bit easier to read the mega-patch.
This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
SE-390 concluded with choosing the keyword discard rather than forget for
the statement that disables the deinit of a noncopyable type. This commit
adds parsing support for `discard self` and adds a deprecation warning for
`_forget self`.
rdar://108859077
- Allow an if/switch expression to become an
implicit return of a function that has a `#if`
body with a single active element that is an `if`
or `switch`.
- Allow `#if` branches of an if/switch expression,
as long as there is a single active expression
element.
rdar://107487977
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
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.
And plumb through the logic such that the
DiagnosticEngine can handle StmtKind. We could
introduce a separate DescriptiveStmtKind a la
DescriptiveDeclKind, but it would be a 1:1 map,
so I'm not convinced it's currently worth doing.
`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
- Unapplied functions: `if #_hasSymbol(foo(_:))`
- Member references: `if #_hasSymbol(a.x)`
- `.self` expressions on static metatypes: `if #_hasSymbol(SomeEnum.self)`
- Dot syntax call expressions with unapplied functions: `if #_hasSymbol(SomeType.init(_:)`
Additionally, we diagnose when the concretely referenced declaration is not weak linked since this likely indicates that the programmer misidentified the declaration they wish to check or the build is not configured in a way such that the check will be meaningful.
Resolves rdar://99826340
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
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.
