Use optimized SmallVec implementation
This PR replaces current SmallVec implementation with the one from the Servo project.
Closes https://github.com/rust-lang/rust/issues/51640
r? @Mark-Simulacrum
* Value gets renamed to Operand, so that now interpret::{Place, Operand} are the
"dynamic" versions of mir::{Place, Operand}.
* Operand and Place share the data for their "stuff is in memory"-base in a new
type, MemPlace. This also makes it possible to give some more precise types
in other areas. Both Operand and MemPlace have methods available to project
into fields (and other kinds of projections) without causing further
allocations.
* The type for "a Scalar or a ScalarPair" is called Value, and again used to
give some more precise types.
* All of these have versions with an attached layout, so that we can more often
drag the layout along instead of recomputing it. This lets us get rid of
`PlaceExtra::Downcast`. MPlaceTy and PlaceTy can only be constructed
in place.rs, making sure the layout is handled properly.
(The same should eventually be done for ValTy and OpTy.)
* All the high-level functions to write typed memory take a Place, and live in
place.rs. All the high-level typed functions to read typed memory take an
Operand, and live in operands.rs.
Exhaustive integer matching
This adds a new feature flag `exhaustive_integer_patterns` that enables exhaustive matching of integer types by their values. For example, the following is now accepted:
```rust
#![feature(exhaustive_integer_patterns)]
#![feature(exclusive_range_pattern)]
fn matcher(x: u8) {
match x { // ok
0 .. 32 => { /* foo */ }
32 => { /* bar */ }
33 ..= 255 => { /* baz */ }
}
}
```
This matching is permitted on all integer (signed/unsigned and char) types. Sensible error messages are also provided. For example:
```rust
fn matcher(x: u8) {
match x { //~ ERROR
0 .. 32 => { /* foo */ }
}
}
```
results in:
```
error[E0004]: non-exhaustive patterns: `32u8...255u8` not covered
--> matches.rs:3:9
|
6 | match x {
| ^ pattern `32u8...255u8` not covered
```
This implements https://github.com/rust-lang/rfcs/issues/1550 for https://github.com/rust-lang/rust/issues/50907. While there hasn't been a full RFC for this feature, it was suggested that this might be a feature that obviously complements the existing exhaustiveness checks (e.g. for `bool`) and so a feature gate would be sufficient for now.
Rollup of bare_trait_objects PRs
All deny attributes were moved into bootstrap so they can be disabled with a line of config.
Warnings for external tools are allowed and it's up to the tool's maintainer to keep it warnings free.
r? @Mark-Simulacrum
cc @ljedrz @kennytm
Use sort_by_cached_key where appropriate
A follow-up to https://github.com/rust-lang/rust/pull/48639, converting various slice sorting calls to `sort_by_cached_key` when the key functions are more expensive.
Modify compile-fail/E0389 error message WIP
This fixes#47388
cc @nikomatsakis @estebank
r? @nikomatsakis
Certain ui tests were failing locally. I'll check if the same happens here too.
