…th 1 when reaching end

These have been bugging me for a while.

- `literal_text`: `src` is also used and is shorter and better.
- `first_char`: used even when "first" doesn't make sense; `c` is
  shorter and better.
- `curr`: `c` is shorter and better.
- `unescaped_char`: `result` is also used and is shorter and better.
- `second_char`: these have a single use and can be elided.

There is some subtlety here.

It's passed to numerous places where we just need an `is_byte` bool.
Passing the bool avoids the need for some assertions.

Also rename `is_bytes()` as `is_byte()`, to better match `Mode::Byte`,
`Mode::ByteStr`, and `Mode::RawByteStr`.

There are three kinds of "byte" literals: byte literals, byte string
literals, and raw byte string literals. None are allowed to have
non-ASCII chars in them.

Two `EscapeError` variants exist for when that constraint is violated.
- `NonAsciiCharInByte`: used for byte literals and byte string literals.
- `NonAsciiCharInByteString`: used for raw byte string literals.

As a result, the messages for raw byte string literals use different
wording, without good reason. Also, byte string literals are incorrectly
described as "byte constants" in some error messages.

This commit eliminates `NonAsciiCharInByteString` so the three cases are
handled similarly, and described correctly. The `mode` is enough to
distinguish them.

Note: Some existing error messages mention "byte constants" and some
mention "byte literals". I went with the latter here, because it's a
more correct name, as used by the Reference.

Remove a low-value comment, remove a duplicate comment, and correct a
third comment.

It deals with eight cases: ints, floats, and the six quoted types
(char/byte/strings). For ints and floats we have an early return, and
the other six types fall through to the code at the end, which makes the
function hard to read.

This commit rearranges things to avoid the early returns.

It has a single callsite, and is fairly small. The `Float` match arm
already has base-specific checking inline, so this makes things more
consistent.

It's easy to just use `unescape_literal` + `byte_from_char`.

This option prints all supported values for -Csplit-debuginfo=.., i.e.
only stable ones on stable/beta and all of them on nightly/dev.

fix: lint against the functions `LintContext::{lookup_with_diagnostics,lookup,struct_span_lint,lint}`, `TyCtxt::struct_lint_node`, `LintLevelsBuilder::struct_lint`.

The `usize` isn't needed in the error case.

this fix rust-lang#103271

…-hang, r=jackh726,wesleywiser

Avoid possible infinite  loop when next_point reaching the end of file

Fixes rust-lang#103451
If we return a span with `lo` = `hi`, `span_to_snippet` will always get `Ok("")`, which may introduce infinite loop if we don't care.

This PR make `find_width_of_character_at_span` return `width` with 1, so that `span_to_snippet` will get an `Err`.

…1-dead

remove redundent "<>" for ty::Slice with reference type

this fix rust-lang#103271

…Simulacrum

Upgrade cc for working is_flag_supported on cross-compiles

rust-lang#85806 fixed unwind v.s gcc support on later Android ndks using `is_flag_supported`. However, due to rust-lang/cc-rs#675, this didn't work properly on cross-compiles. rust-lang/cc-rs@3eeb50b fixes this, and was released in cc 1.0.74, hence the upgrade

…at, r=wesleywiser

Properly remap and check for substs compatibility in `confirm_impl_trait_in_trait_candidate`

Fixes rust-lang#103824

…=matklad

Unescaping cleanups

Some code improvements, and some error message improvements.

Best reviewed one commit at a time.

r? `@matklad`

…ce, r=Mark-Simulacrum

Don't intra linkcheck reference

This removes the reference from the intra-doc link checks. This causes problems if any of the reference content needs to change, it causes the linkchecker to break. The reference has its own broken link check (https://github.com/rust-lang/reference/tree/master/style-check) which uses pulldown-cmark on the source to find actual broken links (instead of false-positives like this regex does).

I think the intra-doc link check could potentially be removed completely, since I think rustdoc is now checking for them well enough. However, it may serve as a decent regression check.

Place config.toml in current working directory if config not found

Fixes an issue where bootsrapping a Rust build would place `config.toml` in `{src_root}` rather than the current working directory

rust-lang#103697

Add split-debuginfo print option

This option prints all supported values for `-Csplit-debuginfo=..`, i.e. only stable ones on stable/beta and all of them on nightly/dev.

Motivated by 1.65.0 regression causing builds with the following entry in `Cargo.toml` to fail on Windows:
```toml
[profile.dev]
split-debuginfo = "unpacked"
```

See rust-lang/cargo#11347 for details.

This will lead to closing rust-lang#103976.

…mpls, r=compiler-errors

Fix `const_fn_trait_ref_impl`, add test for it

rust-lang#99943 broke `#[feature(const_fn_trait_ref_impl)]`, this PR fixes this and adds a test for it.

r? ``@fee1-dead``

…th, r=notriddle

Fix invalid background-image file name

This is a follow-up of rust-lang#101702.

Apparently the image hash was the wrong one. You can see the error in https://doc.rust-lang.org/nightly/core/primitive.u16.html?search=hello too.

I really need to check if I can adds check for resources load errors in `browser-ui-test`.

cc ````@jsha````
r? ````@notriddle````

…=davidtwco

fix: lint against lint functions

Add `#[rustc_lint_diagnostics]` to lint functions missing them. From [this discussion](rust-lang#101138 (comment)).

r? `@davidtwco`