This adds a target specification for Linux kernel modules on x86_64, as well as base code that can be shared with other architectures.

…! arm

PR rust-lang#63580 broke miri's ability to run the run-pass test suite with MIR
optimizations enabled. The issue was that we weren't properly handling
the substs and DefId associated with a Promoted value. This didn't break
anything in rustc because in rustc this code runs before the Inliner
pass which is where the DefId and substs can diverge from their initial
values. It broke Miri though because it ran this code again after
running the optimization pass.

That way, we don't loose the jointness info

They are only used by rustc_lexer, and are not needed elsewhere.

So we move the relevant definitions into rustc_lexer (while the actual
unicode data comes from the unicode-xid crate) and make the rest of
the compiler use it.

On the call site, `rustc_lexer::is_whitespace` reads much better than
`character_properties::is_whitespace`.

We never allowed the warnings, only made them not denied.

Use unicode-xid crate instead of libcore

This PR proposes to remove `char::is_xid_start` and `char::is_xid_continue` functions from `libcore` and use `unicode_xid` crate from crates.io (note that this crate is already present in rust-lang/rust's Cargo.lock).

Reasons to do this:

* removing rustc-binary-specific stuff from libcore
* making sure that, across the ecosystem, there's a single definition of what rust identifier is (`unicode-xid` has almost 10 million downs, as a `proc_macro2` dependency)
* making it easier to share `rustc_lexer` crate with rust-analyzer: no need to `#[cfg]` if we are building as a part of the compiler

Reasons not to do this:

* increased maintenance burden: we'll need to upgrade unicode version both in libcore and in unicode-xid. However, this shouldn't be a too heavy burden: just running `./unicode.py` after new unicode version. I (@matklad) am ready to be a t-compiler side maintainer of unicode-xid. Moreover, given that xid-unicode is an important dependency of syn, *someone* needs to maintain it anyway.
* xid-unicode implementation is significantly slower. It uses a more compact table with binary search, instead of a trie. However, this shouldn't matter in practice, because we have fast-path for ascii anyway, and code size savings is a plus. Moreover, in rust-lang#59706 not using libcore turned out to be *faster*, presumably beacause checking for whitespace with match is even faster.

<details>

<summary>old description</summary>

Followup to rust-lang#59706

r? @eddyb

Note that this doesn't actually remove tables from libcore, to avoid conflict with rust-lang#62641.

cc unicode-rs/unicode-xid#11

</details>

Fix `window.hashchange is not a function`

Closes rust-lang#63707.

Account for doc comments coming from proc macros without spans

Fix rust-lang#63821.

…crichton

Fix unlock ordering in SGX synchronization primitives

Avoid holding spinlocks during usercalls. This should avoid deadlocks in certain pathological scheduling cases.

cc @mzohreva @parthsane

r? @alexcrichton

…nkov

use TokenStream rather than &[TokenTree] for built-in macros

That way, we don't loose the jointness info

…joshtriplett

Add x86_64-linux-kernel target

This adds a target specification for Linux kernel modules on x86_64, as well as base code that can be shared with other architectures.

I wasn't totally sure about what the best name for this was.

There's one open question on whether we should use the LLVM generic x86_64-elf target, or the same one used for the Linux userspace.

r? @joshtriplett

Fix const_err with `-(-0.0)`

Fixes rust-lang#64059

r? @oli-obk

Point at appropriate arm on type error on if/else/match with one non-! arm

Fix rust-lang#61281.

…crichton

Ensure edition lints and internal lints are enabled with deny-warnings=false

Previously we only passed the deny command line flags if deny-warnings was enabled, but now we either pass -W... or -D... for each of the flags as appropriate.

This is also a breaking change to x.py as it changes `--warnings=allow` to `--warnings=warn` which is what that flag actually did; we don't have an allow warnings mode.

…oli-obk

Fix const eval bug breaking run-pass tests in Miri

PR rust-lang#63580 broke miri's ability to run the run-pass test suite with MIR
optimizations enabled. The issue was that we weren't properly handling
the substs and DefId associated with a Promoted value. This didn't break
anything in rustc because in rustc this code runs before the Inliner
pass which is where the DefId and substs can diverge from their initial
values. It broke Miri though because it ran this code again after
running the optimization pass.

r? @oli-obk
cc @RalfJung

…ramertj,Centril

Opaque type locations in error message for clarity.

Attempts to fix rust-lang#63167