local only if matches `FUNDAMENTAL(LocalType)`, where `FUNDAMENTAL`
includes `&T` and types marked as fundamental (which includes `Box`).
Also apply these tests to negative reasoning.
case where `None` was returned should never happen in practice; it
amounts to comparing regions from two unrelated hierarchies. (I was also
not able to make it happen.)
This means passing in e.g. a `Vec<u8>` or `String` will work as
intended, rather than deref-ing to `&mut [u8]` or `&mut str`.
[breaking-change]
Closes#23768
const_eval : add overflow-checking for {`+`, `-`, `*`, `/`, `<<`, `>>`}.
One tricky detail here: There is some duplication of labor between `rustc::middle::const_eval` and `rustc_trans::trans::consts`. It might be good to explore ways to try to factor out the common structure to the two passes (by abstracting over the particular value-representation used in the compile-time interpreter).
----
Update: Rebased atop #23841Fix#22531Fix#23030Fix#23221Fix#23235
The overflow-checking attempts to accommodate early evaluation where
we do not have type information yet.
Also, add fixme note about something that has been bothering me.
Add option-returning variants to `const_to_int`/`const_to_uint` that
never assert fail. (These will be used for overflow checking from
rustc_trans::trans::consts.)
Moved such overflow checking into one place (in `rustc::middle::ty`,
since it needs to be run on-demand during `const_eval` in some
scenarios), and revised `rustc_typeck` accordingly.
(Note that we only check for overflow if program did not provide a
discriminant value explicitly.)
Fix#23030Fix#23221Fix#23235
This commit stabilizes a few remaining bits of the `io::Error` type:
* The `Error::new` method is now stable. The last `detail` parameter was removed
and the second `desc` parameter was generalized to `E: Into<Box<Error>>` to
allow creating an I/O error from any form of error. Currently there is no form
of downcasting, but this will be added in time.
* An implementation of `From<&str> for Box<Error>` was added to liballoc to
allow construction of errors from raw strings.
* The `Error::raw_os_error` method was stabilized as-is.
* Trait impls for `Clone`, `Eq`, and `PartialEq` were removed from `Error` as it
is not possible to use them with trait objects.
This is a breaking change due to the modification of the `new` method as well as
the removal of the trait implementations for the `Error` type.
[breaking-change]
