When an function has an async alternative, that should be preferred when we are completing in an async context. Thus, the sync method should be marked as not recommended if the current context can handle async methods.
rdar://88354910
'available(..., deprecated: <version>)'. If the version is larger than the
current active version, the declaration is "soft deprecated". Emit a
relevant diagnostics for those items. If the version is equal to or
larger than '100000.0', it means the distant future without specifying
the version.
rdar://76122625
* Implement 'getDiagnosticSeverity()' and 'getDiagnosticMessage()' on
'CodeCompletionResult'
* Differentiate 'RedundantImportIndirect' from 'RedundantImport'
* Make non-Sendable check respects '-warn-concurrency'
rdar://76129658
