In order to mitigate the Stale Data Read for xAPIC vulnerability completely, reading userspace from an SGX enclave must be aligned and in 8-bytes chunks.

References:

 - https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00657.html
 - https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/stale-data-read-from-xapic.html

…ifier

…:fill_utf16_buf`

…dead

Mention `as_mut` alongside `as_ref` in borrowck error message

Kinda fixes rust-lang#99426 but I guess that really might be better staying open to see if we could make it suggest `as_mut` in a structured way. Not sure how to change borrowck to know that info tho.

…on, r=cuviper

Mitigate stale data reads on SGX platform

Intel disclosed the Stale Data Read vulnerability yesterday. In order to mitigate this issue completely, reading userspace from an SGX enclave must be aligned and in 8-bytes chunks. This PR implements this mitigation

References:
 - https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00657.html
 - https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/stale-data-read-from-xapic.html

cc: ``@jethrogb``

…er-errors

suggest `once_cell::Lazy` for non-const statics

Addresses rust-lang#100410

Some questions:
 - removing the `if` seems to include too many cases (e.g. calls to non-const functions inside a `const fn`), but this code excludes the following case:
```rust
const FOO: Foo = non_const_fn();
```
Should we suggest `once_cell` in this case as well?
 - The original issue mentions suggesting `AtomicI32` instead of `Mutex<i32>`, should this PR address that as well?

…errors

Suggest the right help message for as_ref

Fixes rust-lang#100605

…=davidtwco

Migrate "invalid variable declaration" errors to SessionDiagnostic

After seeing the great blog post on Inside Rust, I decided to try my hand at this. Just one diagnostic for now to get used to the workflow and to check if this is the way to do it or if there are any problems.

…bol-diagnostic, r=compiler-errors

Migrate typeck's `used` expected symbol diagnostic to `SessionDiagnostic`

r? ``@davidtwco``

…errors

Add the diagnostic translation lints to crates that don't emit them

Some of these have a note saying that they should build on a stable compiler, does that mean they shouldn't get these lints? Or can we cfg them out on those?

…nton

Avoid zeroing a 1kb stack buffer on every call to `std::sys::windows::fill_utf16_buf`

I've also tried to be slightly more careful about integer overflows, although in practice this is likely still not handled ideally.

r? `@ChrisDenton`

…-function-qual-error, r=davidtwco

improved diagnostic for function defined with `def`, `fun`, `func`, or `function` instead of `fn`

Closes rust-lang#99751

triagebot: Autolabel `A-rustdoc-json`