The async refactorings ignore whether a completion handler had
`@escaping` or not. In preparation of fixing this, fix up all functions
to have `@escaping` for their completion handler parameter.
Also some small miscellaneous fixes in order to reduce the number of
warnings output on test failures and also the addition of `REQUIRES:
concurrency` on all tests.
When passing a forwarded error to a CustomError?
completion handler parameter, wrap the cast in a
set of parentheses to silence a warning in the
refactored code.
rdar://80409905
When converting a call or function, rename declarations such that
redeclaration errors and shadowing are avoided. In some cases this will
be overly conservative, but since any renamed variable can be fixed with
edit all in scope, this is preferred over causing redeclaration errors
or possible shadowing.
Resolves rdar://73973517
When a function’s completion handler is being passed to another function and the function that the completion handler is being declared in is converted to async, replace the call to the completion handler by a `return` statement.
For example:
```swift
func foo(completion: (String) -> Void) {
bar(completion)
}
```
becomes
```swift
func foo() async -> String {
return await bar()
}
```
Previously, we were calling the completion handler, which no longer exists in the newly created `async` function.
Previously, we only supported refactoring a function to call the async alternative if a closure was used for the callback parameter. With this change, we also support calling a arbitrary function (or variable with function type) that is passed to the completion handler argument.
The implementation basically re-uses the code we already have to create the legacy function’s body (which calls the newly created async version and then forwards the arguments to the legacy completion handler).
To describe the completion handler that the result is being forwarded to, I’m also using `AsyncHandlerDesc`, but since the completion handler may be a variable, it doesn’t necessarily have an `Index` within a function decl that declares it. Because of this, I split the `AsyncHandlerDesc` up into a context-free `AsyncHandlerDesc` (without an `Index`) and `AsyncHandlerParamDesc` (which includes the `Index`). It turns out that `AsyncHandlerDesc` is sufficient in most places.
Resolves rdar://77460524
