The `call` argument to `diagnoseDeclAsyncAvailability()` may be `nullptr` when the structure of the AST prevents `getEnclosingApplyExpr()` from finding the enclosing apply. The diagnostics implementation introduced with https://github.com/apple/swift/pull/60663 needs to tollerate this, similar to the rest of `diagnoseDeclAsyncAvailability()`.
Resolves rdar://100862513
The completion handler async replacement moved from being its own
attribute to being an availability attribute. This patch moves the
checking from being its own pass to being part of the availability
checking under the async availability checking diagnostic pass.
A lookup on the name provided by `renamed` in `@available` returns the
VarDecl. If the name specified a getter or setter, make sure to grab the
corresponding accessor when comparing candidates.
We currently ignore the basename and parameters specified in the name
for accessors. Checking them would only cause a getter/setter not to
match, there can never be a conflict. Since this is a best effort match
anyway, this seems fine.
Instead of a new attribute `@completionHandlerAsync`, allow the use of
the existing `renamed` parameter of `@available` to specify the
asynchronous alternative of a synchronous function.
No errors will be output from invalid names as `@completionHandlerAsync`
had, but if a function is correctly matched then it will be used to
output warnings when using the synchronous function in an asynchronous
context (as before).
Resolves rdar://80612731
