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.
`addExplicitConversionConstraint` generates a disjunction to check
whether type could be coerced via bridging. That is not useful for
literal initialization which could use direct equality if the type
of cast is valid because necessary conformance checks have been
performed before the transformation.
It's possible for out-of-scope type variable to be the type of
declaration if such declaration is recursively referenced in
the body of a closure located in its initializer expression.
In such cases type of the variable declaration cannot be connected
to the closure because its not known in advance (determined by the
initializer itself).
Resolves: https://github.com/apple/swift/issues/63455
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.
Describe attached macros with the `@attached` attribute, providing the
macro role and affected names as arguments to the macro. The form of
this macro will remain the same as it gains other kinds of attached
macro roles beyond "accessor".
Remove the "accessors" role from `@declaration`, which will be going
away.
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.
While trying to gather all references to external variables,
analyzer shouldn't walk into patterns and any local declarations
except to pattern bindings, because decls do not participate
in inference and patterns cannot contain references analyzer
is looking for.
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 relying on PackElementExprs collected by preCheck.
This handles pack element expressions and pack element type reprs, and enforces that
all packs expanded by a given pack expansion expression all have the same shape.
Once the parser creates PackExpansionExpr directly (based on a dedicated syntax instead
of postfix '...'), the code in preCheck for identifying and creating pack expansions
can simply be deleted.
of assigning it to std::function_ref.
std::function_ref does not own the function reference, so assigning an OpenPackElementType
to a local function_ref lead to stale constraint system references when invoking
operator () later on.
constraints, vend potential bindings through PotentialBindings::infer.
This allows for bidirectional binding inference from the pack type to the
element type and vice versa.
