mk: add a all-no-docs target to build everything except docs

This makes things slightly more efficient for Debian's auto-builders where the
docs can be built on just one architecture, and distributed to users of all
other architectures as well.

Fix overflow checking in unsigned pow()

The pow() method for unsigned integers produced 0 instead of trapping overflow for certain inputs. Calls such as 2u32.pow(1024) produced 0 when they should trap an overflow. This also adds tests for the correctly handling overflow in unsigned pow().

This was previously fixed for signed integers in #28248, but it seems unsigned integers got missed that time.

For issue number #34913

Rustc metadata diagnostics

r? @jonathandturner

Remove unused Token::to_binop function

Just some dead code removal.

Remove stray println! when invoking error E0316

Removed a wild println! statement that has been here for over a year and a half.

Closes #36543

Add links between format_args! macro and std::fmt::Arguments struct

r? @GuillaumeGomez

save-analysis: better 'parent' info

In particular, this fixes some bugs displaying doc URLs for method calls.

In particular, this fixes some bugs displaying doc URLs for method calls.

Add basic doc examples for `std::panic::{set_hook, take_hook}`.

None

Visit and fold macro invocations in the same order

Fixes #36540.
r? @nrc

Optimize the parser's last token handling.

The parser currently makes a heap copy of the last token in four cases:
identifiers, paths, doc comments, and commas. The identifier and
interpolation cases are unused, and for doc comments and commas we only
need to record their presence, not their value.

This commit consolidates the last token handling and avoids the
unnecessary copies by replacing `last_token`, `last_token_eof`, and
`last_token_interpolated` with a new field `last_token_kind`. This
simplifies the parser slightly and speeds up parsing on some files by
3--4%.

correctly cancel some errors

Fixes #36499.

I also (proactively) changed all other calls in `parser.rs` to use `Handler::cancel`.

librustc_mir: Remove `&*x` when `x` has a reference type.

This introduces a new `InstCombine` pass for us to place such peephole
optimizations.

r? @EddyB

Up the LLVM

Fixes #36474

The relevant patch to rust-llvm is at https://github.com/rust-lang/llvm/pull/51

r? @alexcrichton

Fixes #36474

Remove data structure specialization for .zip() iterator

Go back on half the specialization, the part that changed the Zip
struct's fields themselves depending on the types of the iterators.

Previous PR: #33090

This means that the Zip iterator will always carry two usize fields,
which are sometimes unused. If a whole for loop using a .zip() iterator is
inlined, these are simply removed and have no effect.

The same improvement for Zip of for example slice iterators remain, and
they still optimize well. However, like when the specialization of zip
was merged, the compiler is still very sensistive to the exact context.

For example this code only autovectorizes if the function is used, not
if the code in zip_sum_i32 is inserted inline where it was called:

```rust
fn zip_sum_i32(xs: &[i32], ys: &[i32]) -> i32 {
    let mut s = 0;
    for (&x, &y) in xs.iter().zip(ys) {
        s += x * y;
    }
    s
}

fn zipdot_i32_default_zip(b: &mut test::Bencher)
{
    let xs = vec![1; 1024];
    let ys = vec![1; 1024];

    b.iter(|| {
        zip_sum_i32(&xs, &ys)
    })
}
```

Include a test that checks that `Zip<T, U>` is covariant w.r.t. T and U.

Fixes #35727

Overhaul char_lit()

This commit does the following.

- Removes parsing support for '\X12', '\u123456' and '\U12345678' char
  literals. These are no longer valid Rust and rejected by the lexer.
  (This strange-sounding situation occurs because the parser rescans
  char literals to compute their value.)

- Rearranges the function so that all the escaped values are handled in
  a single `match`. The error-handling strategy is based on the one used
  by byte_lit().