There's no need to have it given it merely forwarded to RustbookSrc.

Removing the tool argument in the previous commit means it's no longer
restricted to just bootstrap tools despite being written as such.
Inlining it prevents accidental use.

There's no reason for it to be std-based

Fixes rust-lang#61604

Co-Authored-By: Mazdak Farrokhzad <twingoow@gmail.com>

…racters alone

This commit fixes an ICE that occured when a const generic was used in
a repeat expression. This was due to the code expecting the length of
the repeat expression to be const evaluatable to a constant, but a const
generic parameter is not (however, it can be made into a constant).

This is duplicated in a few locations throughout the sysroot to work
around issues with not exporting a macro in libstd but still wanting it
available to sysroot crates to define blocks. Nowadays though we can
simply depend on the `cfg-if` crate on crates.io, allowing us to use it
from there!

…tor`

It's a less powerful duplicate of `SyntaxExtension::NormalTT`

We already use this for `unzip`, but `partition` is not much different.

move some tests into subfolders

This reduces the size of the test folders without making the moved tests harder to find.

Is this kind of change desired/worth the effort?

Windows 10 SDK is also required now.

Remove some legacy proc macro flavors

Namely
- `IdentTT` (`foo! ident { ... }`). Can be replaced with `foo! { ident ... }` or something similar.
- `MultiDecorator`. Can be replaced by `MultiModifier` (aka `LegacyAttr` after renaming).
- `DeclMacro`. It was a less powerful duplicate of `NormalTT` (aka `LegacyBang` after renaming) and can be replaced by it.

Stuff like this slows down any attempts to refactor the expansion infra, so it's desirable to retire it already.
I'm not sure whether a lang team decision is necessary, but would be nice to land this sooner because I have some further work in this area scheduled.

The documentation commit (rust-lang@a9397fd) describes how the remaining variants are different from each other and shows that there's actually some system behind them.

The last commit renames variants of `SyntaxExtension` in more systematic way.
- `ProcMacro` -> `Bang`
- `NormalTT` -> `LegacyBang`
- `AttrProcMacro` -> `Attr`
- `MultiModifier` -> `LegacyAttr`
- `ProcMacroDerive` -> `Derive`
- `BuiltinDerive` -> `LegacyDerive`

All the `Legacy*` variants are AST-based, as opposed to "modern" token-based variants.

…r=alexcrichton

Bootstrap cleanup

Each commit is (mostly) standalone and probably best reviewed as such. Nothing too major just some drive-by nits as I was looking through the code.

r? @alexcrichton

…ebank

librustc_errors: Add some more documentation

r? @estebank

… r=varkor

typeck: Fix const generic in repeat param ICE.

Fixes rust-lang#61336. Turns out this wasn't related to rust-lang#49147 after all.

r? @varkor

…chton

Azure: retry failed awscli installs

Fixes rust-lang#61604

r? @pietroalbini

…rkor

make sure make_ascii_lowercase actually leaves upper-case non-ASCII characters alone

Cc rust-lang#61677 @napen123

…fackler

std: Remove internal definitions of `cfg_if!` macro

This is duplicated in a few locations throughout the sysroot to work
around issues with not exporting a macro in libstd but still wanting it
available to sysroot crates to define blocks. Nowadays though we can
simply depend on the `cfg-if` crate on crates.io, allowing us to use it
from there!

core: use memcmp optimization for 128 bit integer slices

All other sized integer slices do this. From rust-lang#61665.

Use `for_each` in `Iterator::partition`

We already use this for `unzip`, but `partition` is not much different.