syntax: Optimize some literal parsing

Currently in the `wasm-bindgen` project we have a very very large crate that's
procedurally generated, `web-sys`. To generate this crate we parse all of a
browser's WebIDL and we then generate bindings for all of the APIs contained
within.

The resulting Rust file is 18MB large (wow!) and currently takes a very long
time to compile in debug mode. On the nightly compiler a *debug* build takes 90s
for the crate to finish. I was curious what was taking so long and upon
investigating a *massive* portion of the time was spent in the `lit_token`
method of the compiler, primarily formatting strings via `format!`.

Upon some more investigation it looks like the `byte_str_lit` was allocating an
error message once per byte, causing a very large number of allocations to
happen for large literals, of which wasm-bindgen generates quite a few (some are
MB large).

This commit fixes the issue by lazily allocating the error message, only doing
so if the error message is actually needed (which should be never). As a result,
the debug mode compilation time for our `web-sys` crate decreased from 90s to
20s, a very nice improvement! (although we've still got some work to do).

Fix typos found by codespell.

update lld submodule to include RISCV patch

This pulls in one new commit, to add support for linking static RISCV
binaries, suitable for the new riscv32imac-unknown-none-elf target.
See: https://github.com/rust-lang/lld/pull/1

Remove LinkMeta struct

Fixes #53291

Change target triple used to check for lldb in build-manifest

The wrong target triple was used for lldb in build-manifest.  lldb is
only built for macOS, so update the triple to reflect that.

This is an attempt to fix bug#48168.

restore the page title after escaping out of a search

Currently if I start a search in the docs, but then hit ESC, the "Results for..." title is still there in my browser tab. This is a simple attempt to fix that. I see that there's a separate `var previousTitle = document.title` thing happening in `startSearch()`, but as far as I can tell that's only related to the back stack? I'd also appreciate feedback on the right place to declare the `titleBeforeSearch` variable.

Testing-wise, I've confirmed by hand that the tab title restores correctly after building with `./x.py doc --stage 1 src/libstd`, but nothing more involved than that. What else should I test?

Mark libserialize functions as inline

Got to thinking: "what if that big pile of tiny functions isn't inlining as it should?"
So a few `replace-regex` later the local perf run says this:
<details>

![](https://i.imgur.com/gvdJEgG.png)
</details>
Not huge, but still a win, which is interesting. Want to verify with the real perf run, but I understand there's a backlog.

I didn't notice any increase in compile time or binary sizes for rustc/libs.

Stabilize macro_vis_matcher

This PR should stabilize [macro_vis_matcher](https://github.com/rust-lang/rust/issues/41022) feature.

- [ ] "reference" book changes: https://github.com/rust-lang-nursery/reference/pull/400
- [ ] "Rust by example" book changes: https://github.com/rust-lang/rust-by-example/pull/1096
- [ ] "clippy" changes: https://github.com/rust-lang-nursery/rust-clippy/pull/3055

r? @cramertj

Currently in the `wasm-bindgen` project we have a very very large crate that's
procedurally generated, `web-sys`. To generate this crate we parse all of a
browser's WebIDL and we then generate bindings for all of the APIs contained
within.

The resulting Rust file is 18MB large (wow!) and currently takes a very long
time to compile in debug mode. On the nightly compiler a *debug* build takes 90s
for the crate to finish. I was curious what was taking so long and upon
investigating a *massive* portion of the time was spent in the `lit_token`
method of the compiler, primarily formatting strings via `format!`.

Upon some more investigation it looks like the `byte_str_lit` was allocating an
error message once per byte, causing a very large number of allocations to
happen for large literals, of which wasm-bindgen generates quite a few (some are
MB large).

This commit fixes the issue by lazily allocating the error message, only doing
so if the error message is actually needed (which should be never). As a result,
the debug mode compilation time for our `web-sys` crate decreased from 90s to
20s, a very nice improvement! (although we've still got some work to do).

When closure with no arguments was expected, suggest wrapping

Fix #49694.

Stabilize IP associated constants

Fixes #44582

Updated RELEASES.md for 1.29.0

[Rendered](https://github.com/Aaronepower/rust/blob/master/RELEASES.md)

r? @Mark-Simulacrum
cc @rust-lang/release

Add the identity function as core::convert::identity

## New notes

This implements rust-lang/rfcs#2306 (see https://github.com/rust-lang/rust/issues/53500).

## Old notes (ignore this in new reviews)

Adds the identity function `fn id<T>(x: T) -> T { x }` to core::convert and the prelude.
Some motivations for why this is useful are explained in the doc tests.
Another is that using the identity function instead of `{ x }` or `|x| x` makes it clear that you intended to use an identity conversion on purpose.

The reasoning:
+ behind adding this to `convert` and not `mem` is that this is an identity *conversion*.
+ for adding this to the prelude is that it should be easy enough to use that the ease of writing your own identity function or using a closure `|x| x` doesn't overtake that.

I've separated this out into two feature gates so that the addition to the prelude can be considered and stabilized separately.

cc @bluss

Update clippy

r? @oli-obk @EddyB

try to infer linker flavor from linker name and vice versa

This is a second take on PR #50359 that implements the logic proposed in https://github.com/rust-lang/rust/pull/50359#pullrequestreview-116663121

With this change it would become possible to link `thumb*` binaries using GNU's LD on stable as `-C linker=arm-none-eabi-ld` would be enough to change both the linker and the linker flavor from their default values of `arm-none-eabi-gcc` and `gcc`.

To link `thumb*` binaries using rustc's LLD on stable `-Z linker-flavor` would need to be stabilized as `-C linker=rust-lld -Z linker-flavor=ld.lld` are both required to change the linker and the linker flavor, but this PR doesn't propose that. We would probably need some sort of stability guarantee around `rust-lld`'s name and availability to make linking with rustc's LLD truly stable.

With this change it would also be possible to link `thumb*` binaries using a system installed LLD on stable using the `-C linker=ld.lld` flag (provided that `ld.lld` is a symlink to the system installed LLD).

r? @alexcrichton

Rename CodeMap/FileMap to SourceMap/SourceFile

A first renaming for #51574

52985: cause cycle err on inf trait normalization

Issue: #52985
 - If an existential type is defined, but no user code infers the
concrete type behind the existential type, normalization would
infinitely recurse on this existential type which is only defined in
terms of itself.
  - Instead of raising an inf recurse error, we cause a cycle error to
help highlight that the issue is that the type is only defined in terms
of itself.
  - Three known potential improvements:
    - If type folding itself was exposed as a query, used by
normalization and other mechanisms, cases that would cause infinite recursion would
automatically cause a cycle error.
    - The span for the cycle error should be improved to point to user
code that fails to allow inference of the concrete type of the existential type,
assuming that this error occurs because no user code can allow inference the
concrete type.
    - A mechanism to extend the cycle error with a helpful note would be nice. Currently,
the error is built and maintained by src/librustc/ty/query/plumbing,
with no known way to extend the information that the error gets built
with.

r? @oli-obk

optimize reassignment immutable state

This is the "simple fix" when it comes to checking for reassignment. We just shoot for compatibility with the AST-based checker. Makes no attempt to solve #21232.

I opted for this simpler fix because I didn't want to think about complications [like the ones described here](https://github.com/rust-lang/rust/issues/21232#issuecomment-412219247).

Let's do some profiling measurements.

Fixes #53189

r? @pnkfelix

skip trivial `Sized` predicates

This came to about a 2% win for me in cargo. Small, but hey.

r? @EddyB

now compare-mode can show us the differences

We did not seem to have any!