This avoids having to convert from `ErrorKind` to `Error` just to print the error message.

…=jackh726

Fix suggestion to slice if scrutinee is a `Result` or `Option`

Fixes rust-lang#91328.

Implement `RawWaker` and `Waker` getters for underlying pointers

implement rust-lang#87021

New APIs:
- `RawWaker::data(&self) -> *const ()`
- `RawWaker::vtable(&self) -> &'static RawWakerVTable`
- ~`Waker::as_raw_waker(&self) -> &RawWaker`~ `Waker::as_raw(&self) -> &RawWaker`

This third one is an auxiliary function to make the two APIs above more useful. Since we can only get `&Waker` in `Future::poll`, without this, we need to `transmute` it into `&RawWaker` (relying on `repr(transparent)`) in order to access its data/vtable pointers.

~Not sure if it should be named `as_raw` or `as_raw_waker`. Seems we always use `as_<something-raw>` instead of just `as_raw`. But `as_raw_waker` seems not quite consistent with `Waker::from_raw`.~ As suggested in rust-lang#91828 (comment), use `as_raw`.

…=Mark-Simulacrum

Eliminate duplicate codes of is_single_fp_element

There are duplicate codes of is_single_fp_element function. Merge these codes to TyAndLayout impl block.
![image](https://user-images.githubusercontent.com/95843988/146707753-ba9ffc41-5888-4a53-80cf-f4fe3bcbac54.png)

…iser

If an integer is entered with an upper-case base prefix (0Xbeef, 0O755, 0B1010), suggest to make it lowercase

The current error for this case isn't really great, it just complains about the whole thing past the `0` being an invalid suffix.

`impl Display for io::ErrorKind`

This avoids having to convert from `ErrorKind` to `Error` just to print the error message.

implement a lint for suspicious auto trait impls

cc rust-lang#85048 (comment)

r? ``@nikomatsakis``

…=michaelwoerister

Remove an unnecessary transmute from opaque::Encoder

…r=nagisa

kmc-solid: Increase the default stack size

This PR increases the default minimum stack size on the [`*-kmc-solid_*`](https://doc.rust-lang.org/nightly/rustc/platform-support/kmc-solid.html) Tier 3 targets to 64KiB (Arm) and 128KiB (AArch64).

This value was chosen as a middle ground between supporting a relatively complex program (e.g., an application using a full-fledged off-the-shelf web server framework) with no additional configuration and minimizing resource consumption for the embedded platform that doesn't support lazily-allocated pages nor over-commitment (i.e., wasted stack spaces are wasted physical memory). If the need arises, the users can always set the `RUST_MIN_STACK` environmental variable to override the default stack size or use the platform API directly.