Implemented as custom parsing logic instead of a proper attribute because we want it to be rewritten at parse time (into nothing in regular Swift mode, and into unconditional unavailable attr in embedded Swift mode), no serialization, printing, etc.
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.
We didn’t actually have any tests for this. Completions aren’t great here at the moment but since this is an underscored language feature it’s not that important at the moment.
This attribute can be attached to a noncopyable struct to specify that its
storage is raw, meaning the type definition is (with some limitations)
able to do as it pleases with the storage. This provides a basis for
implementing types for things like atomics, locks, and data structures
that use inline storage to store conditionally-initialized values.
The example in `test/Prototypes/UnfairLock.swift` demonstrates the use
of a raw layout type to wrap Darwin's `os_unfair_lock` APIs, allowing
a lock value to be stored inside of classes or other types without
needing a separate allocation, and using the borrow model to enforce
safe access to lock-guarded storage.
As of CMake 3.25, there are now global variables `LINUX=1`, `ANDROID=1`,
etc. These conflict with expressions that used these names as unquoted
strings in positions where CMake accepts 'variable|string', for example:
- `if(sdk STREQUAL LINUX)` would fail, because `LINUX` is now defined and
expands to 1, where it would previously coerce to a string.
- `if(${sdk} STREQUAL "LINUX")` would fail if `sdk=LINUX`, because the
left-hand side expands twice.
In this patch, I looked for a number of patterns to fix up, sometimes a
little defensively:
- Quoted right-hand side of `STREQUAL` where I was confident it was
intended to be a string literal.
- Removed manual variable expansion on left-hand side of `STREQUAL`,
`MATCHES` and `IN_LIST` where I was confident it was unintended.
Fixes#65028.
As with the initial value of a property that is converted from a stored
property to a computed property by an accessor macro, remove
didSet/willSet. It is the macro's responsibility to incorporate their
code or diagnose them.
Fixes rdar://111101833.
Address a few related issues that affect local types and opaque result types within macros:
* Don't add local types or opaque types encountered while parsing the
arguments of a freestanding macro to the global list. When we do add
them, make sure we're adding them to the outermost source file so
they'll get seen later. This avoids trying to generate code for these
types, because they aren't supposed to be part of the program. Note
that a similar problem remains for arguments to attached macros, which
will need to be addressed with a more significant refactoring.
* When determining whether opaque types should be substituted within a
resilience domain, check the outermost source files rather than the exact
source file, otherwise we will end up with a mismatch in
argument-passing conventions.
* When delaying the type checking of functions that occur as part of a
macro expansion, make sure we record them in the outermost Swift source
file. Otherwise, we won't come back to them.
There is a common theme here of using AST state on the source file in
a manner that isn't ideal, and starts to break down with macros. In
these cases, we're relying on side effects from earlier phases
(parsing and type checking) to inform later phases, rather than
properly expressing the dependencies through requests.
Fixes rdar://110674997&110713264.
Attribute @_silgen_name is today only allowed to be used on functions, this change allows usage on globals as well. The motivation for that is to be able to "forward declare" globals just like it's today possible to do with functions (for the cases where it's not practical or convenient to use a bridging header).
Separately, this change also adds a @_silgen_name(raw: ...) syntax, which simply avoids mangling the name (by using the \01 name prefix that LLVM uses). The motivation for that is to be able to reference the "magic Darwin linker symbols" that can be used to look up section bounds (in the current dylib/module) -- those symbols don't use the underscore prefix in their mangled names.
