The E0397 explanation, as I've written it, isn't really an explanation, but I'm not sure what to put here. I will happily take suggestions.
Partially addresses https://github.com/rust-lang/rust/issues/25851
This adds an example from mem::swap, and provides some suggested uses of this
function.
This is my attempt to summarize the answers to a question I asked on reddit http://www.reddit.com/r/rust/comments/37jcul/what_is_forget_for/ and add the answers to the documentation so that no one else has to google or ask the question again.
This commit implements a number of standard traits for the standard library's
process I/O handles. The `FromRaw{Fd,Handle}` traits are now implemented for the
`Stdio` type and the `AsRaw{Fd,Handle}` traits are now implemented for the
`Child{Stdout,Stdin,Stderr}` types.
The stability markers for these implementations mention that they are stable for
1.1 as I will nominate this commit for cherry-picking to beta.
This adds an example from mem::swap, and provides some suggested uses of this
function.
Change wording on comment on forget line to be more specific as to why we
need to call forget.
This breaks the examples up into three pieces. The last piece isn't
compiling for some reason.
The previous feature gate assumed we would not define any (stable) const fns. But then @eddyb went and cleaned up the code. So this now extends the feature-gate to prohibit calls; but calls inside of macros are considered ok.
r? @alexcrichton
For slightly complex data structures like `rustc_serialize::json::Json`, it is often convenient to have helper methods like `Json::as_string(&self) -> Option<&str>` that return a borrow of some component of `&self`.
However, when `RefCell`s are involved, keeping a `Ref` around is required to hold a borrow to the insides of a `RefCell`. But `Ref` so far only references the entirety of the contents of a `RefCell`, not a component. But there is no reason it couldn’t: `Ref` internally contains just a data reference and a borrow count reference. The two can be dissociated.
This adds a `map_ref` function that creates a new `Ref` for some other data, but borrowing the same `RefCell` as an existing `Ref`.
Example:
```rust
struct RefCellJson(RefCell<Json>);
impl RefCellJson {
fn as_string(&self) -> Option<Ref<str>> {
map_ref(self.borrow(), |j| j.as_string())
}
}
```
r? @alexcrichton
The first commit simply forwards `io::Error`'s `cause` implementation to the inner error.
The second commit adds accessor methods for the inner error. Method names mirror those used elsewhere like `BufReader`.
r? @alexcrichton
