https://github.com/rust-lang/rfcs/pull/221
The current terminology of "task failure" often causes problems when
writing or speaking about code. You often want to talk about the
possibility of an operation that returns a Result "failing", but cannot
because of the ambiguity with task failure. Instead, you have to speak
of "the failing case" or "when the operation does not succeed" or other
circumlocutions.
Likewise, we use a "Failure" header in rustdoc to describe when
operations may fail the task, but it would often be helpful to separate
out a section describing the "Err-producing" case.
We have been steadily moving away from task failure and toward Result as
an error-handling mechanism, so we should optimize our terminology
accordingly: Result-producing functions should be easy to describe.
To update your code, rename any call to `fail!` to `panic!` instead.
Assuming you have not created your own macro named `panic!`, this
will work on UNIX based systems:
grep -lZR 'fail!' . | xargs -0 -l sed -i -e 's/fail!/panic!/g'
You can of course also do this by hand.
[breaking-change]
Spring cleaning is here! In the Fall! This commit removes quite a large amount
of deprecated functionality from the standard libraries. I tried to ensure that
only old deprecated functionality was removed.
This is removing lots and lots of deprecated features, so this is a breaking
change. Please consult the deprecation messages of the deleted code to see how
to migrate code forward if it still needs migration.
[breaking-change]
A few notable improvements were implemented to cut down on the number of aborts
triggered by the standard library when a local task is not found.
* Primarily, the unwinding functionality was restructured to support an unsafe
top-level function, `try`. This function invokes a closure, capturing any
failure which occurs inside of it. The purpose of this function is to be as
lightweight of a "try block" as possible for rust, intended for use when the
runtime is difficult to set up.
This function is *not* meant to be used by normal rust code, nor should it be
consider for use with normal rust code.
* When invoking spawn(), a `fail!()` is triggered rather than an abort.
* When invoking LocalIo::borrow(), which is transitively called by all I/O
constructors, None is returned rather than aborting to indicate that there is
no local I/O implementation.
* Invoking get() on a TLD key will return None if no task is available
* Invoking replace() on a TLD key will fail if no task is available.
A test case was also added showing the variety of things that you can do without
a runtime or task set up now. In general, this is just a refactoring to abort
less quickly in the standard library when a local task is not found.
