Allow freestanding macros to be used at top-level.
- Parse top-level `#…` as `MacroExpansionDecl` when we are not in scripting mode.
- Add macro expansion decls to the source lookup cache with name-driven lazy expansion. Not supporting arbitrary name yet.
- Experimental support for script mode and brace-level declaration macro expansions: When type-checking a `MacroExpansionExpr`, assign it a substitute `MacroExpansionDecl` if the macro reference resolves to a declaration macro. This doesn’t work quite fully yet and will be enabled in a future fix.
Previously enum AccessLimitKind was
added to distinguish access scopes b/t package and public while keeping
DeclContext null but it proved to be too limiting. This PR creates package specific entries for DeclContext and
ASTHierarchy. It create a new class PackageUnit that can be set as the parent DeclContext of ModuleDecl. This PR
contains addition of such entries but not the use of them; the actual use of them will be in the upcoming PRs.
Resolves rdar://106155600
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.
The macro role argument presented an opportunity for callers to accidentally
invoke this request twice for the same macro with slightly different macro
roles passed in, which resulted in re-typechecking the macro arguments.
Instead, derive the corresponding macro roles from the macro reference syntax.
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.
People can call `withoutActuallyEscaping` and give it a `do:` body function
that, well, doesn't actually take an escaping closure argument as in:
```swift
func foo(_ f: (() -> Void) -> Void, _ b: () -> Void) {
return withoutActuallyEscaping(b, do: f)
}
```
and this wouldn't really work because the did-it-escape checking relies on
having a refcounted object to probe, aside from triggering a bunch of
assertion failures in SILGen which assumed the parameter would be escaping.
Fixes rdar://104477418.
Introduce discriminators into freestanding macro expansion expressions
and declarations. Compute these discriminators alongside closure and
local-declaration discriminators, checking them in the AST verifier.
Always parse macro expansions, regardless of language mode, and
eliminate the fallback path for very, very, very old object literals
like `#Color`. Instead, check for the feature flag for macro
declaration and at macro expansion time, since this is a semantic
restriction.
While here, refactor things so the vast majority of the macro-handling
logic still applies even if the Swift Swift parser is disabled. Only
attempts to expand the macro will fail. This allows us to enable the
macro-diagnostics test everywhere.
Rather than set closure discriminators in both the parser (for explicit
closures) and then later as part of contextualizing closures (for
autoclosures), do so via a request that sets all of the discriminators
for a given context.
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.
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.
For synthesized `<async iterator>.next()` calls expression rewriter
has to check whether witness is throwing and add `try` when necessary,
in order to do that injector needs to look through opened existentials,
erasures, and other implicitly injected AST nodes.
Allow user-defined macros to be loaded from dynamic libraries and evaluated.
- Introduce a _CompilerPluginSupport module installed into the toolchain. Its `_CompilerPlugin` protocol acts as a stable interface between the compiler and user-defined macros.
- Introduce a `-load-plugin-library <path>` attribute which allows users to specify dynamic libraries to be loaded into the compiler.
A macro library must declare a public top-level computed property `public var allMacros: [Any.Type]` and be compiled to a dynamic library. The compiler will call the getter of this property to obtain and register all macros.
Known issues:
- We current do not have a way to strip out unnecessary symbols from the plugin dylib, i.e. produce a plugin library that does not contain SwiftSyntax symbols that will collide with the compiler itself.
- `MacroExpansionExpr`'s type is hard-coded as `(Int, String)`. It should instead be specified by the macro via protocol requirements such as `signature` and `genericSignature`. We need more protocol requirements in `_CompilerPlugin` to handle this.
- `dlopen` is not secure and is only for prototyping use here.
Friend PR: apple/swift-syntax#1022
