Use `Decl::attachParsedAttrs()` instead of `Decl::setAttrs()` to attach attributes to a declaration in ASTGen. This causes the common attribute-setup logic there to be run.
NFC in this commit because none of the attributes that have special setup logic are currently implemented in ASTGen. Prepares to add support for `@abi` in a future commit.
What’s implemented now is actually *far* more thorough than what the surface syntax can currently express, mainly because I can’t apply @abi to nominal types yet.
Check for:
• Matching decl kinds
• Matching PBD shapes (does every VarDecl on both sides have a counterpart?)
• Matching function effects
• Matching function arity (roughly)
Sema now type-checks the alternate ABI-providing decls inside of @abi attributes.
Making this work—particularly, making redeclaration checking work—required making name lookup aware of ABI decls. Name lookup now evaluates both API-providing and ABI-providing declarations. In most cases, it will filter ABI-only decls out unless a specific flag is passed, in which case it will filter API-only decls out instead. Calls that simply retrieve a list of declarations, like `IterableDeclContext::getMembers()` and friends, typically only return API-providing decls; you have to access the ABI-providing ones through those.
As part of that work, I have also added some basic compiler interfaces for working with the API-providing and ABI-providing variants. `ABIRole` encodes whether a declaration provides only API, only ABI, or both, and `ABIRoleInfo` combines that with a pointer to the counterpart providing the other role (for a declaration that provides both, that’ll just be a pointer to `this`).
Decl checking of behavior specific to @abi will come in a future commit.
Note that this probably doesn’t properly exercise some of the new code (ASTScope::lookupEnclosingABIAttributeScope(), for instance); I expect that to happen only once we can rename types using an @abi attribute, since that will create distinguishable behavior differences when resolving TypeReprs in other @abi attributes.
The new `DECL_ATTR_FEATURE_REQUIREMENT` macro in DeclAttr.def can be used to declare that an attribute should only be available when a related language feature is enabled.
Effects:
• `#if hasAttribute(someAttr)` will return `false` unless the required feature is enabled.
• Code completion will not include the attribute unless the required feature is enabled.
• `TypeChecker::checkDeclAttributes()` diagnoses non-implicit uses of the attribute.
Add this mechanism and use it to tie @abi to the ABIAttribute feature. Also design tests for it.
This attribute will allow you to specify an alternate version of the declaration used for mangling. It will allow minor adjustments to be made to declarations so long as they’re still compatible at the calling convention level, such as refining isolation or sendability, renaming without breaking ABI, etc.
The attribute is behind the experimental feature flag `ABIAttribute`.
The `@differentiable` and `@derivative` attributes need a parent pointer. Move the code to populate it from Parser to AST so it can be more easily shared between the parsers.
Done in preparation for similar code to be added for `@abi`.
There were two cache replay code exists, one for cache replay from
swift-frontend, the other for replay using C API from libSwiftScan. It
is easy to forget to update one copy when new specialized cache replay
logic is added for some output kinds. Now unify the replay logics to a
single location to avoid confusion. This is a rewrite of the existing
logic and NFCI.
And move the implementation of `SIL.Type.canBeClass` to the AST Type. The SIL Type just calls the AST Type implementation.
Also rename `SIL.Type.canonicalASTType` -> `SIL.Type.astType`.
This convenience returns an optional `SemanticAvailableAttr` (since in the
future, lookup of the `AvailabilityDomain` can fail). It replaces
`Decl::getDomainForAvailableAttr()`, since most callers will need to form a
`SemanticAvailableAttr` with the resulting domain anyways.
This new attribute iterator returned from the query makes it simpler to
implement algorithms that need access to both the `AvailableAttr *` and its
corresponding `AvailabilityDomain`. This is also work towards making it
possible to return an optional `AvailabilityDomain` from
`Decl::getDomainForAvailableAttr()`.
This was never used to generate a .swiftinterface, so can be safely removed. It
was used to guard compiler fixes that might break older .swiftinterface
files. Now, we guard the same fixes by checking the source file type.
Instead of starting a depth-first search from each type variable
and marking all type variables that haven't been marked yet,
we can implement this as a union-find.
We can also store the temporary state directly inside the
TypeVariableType::Implementation, instead of creating large
DenseMaps whose keys range over all type variables.
