…t_unchecked` in `Zip` `TrustedRandomAccess` specialization

Otherwise if `Iterator::self.a.__iterator_get_unchecked` panics the
index would not have been incremented yet and another call to
`Iterator::next` would read from the same index again, which is not
allowed according to the API contract of `TrustedRandomAccess` for
`!Clone`.

Fixes rust-lang#81740

…n't be shipped on all targets

We now allow two new casts:

- mut array reference to mut ptr. Example:

      let mut x: [usize; 2] = [0, 0];
      let p = &mut x as *mut usize;

  We allow casting const array references to const pointers so not
  allowing mut references to mut pointers was inconsistent.

- mut array reference to const ptr. Example:

      let mut x: [usize; 2] = [0, 0];
      let p = &mut x as *const usize;

  This was similarly inconsistent as we allow casting mut references to
  const pointers.

Existing test 'vector-cast-weirdness' updated to test both cases.

Fixes rust-lang#24151

Updates `tools.mk` to explicitly require `SHELL := /bin/dash`, since CI
uses `dash` but other environments (including developer local machines)
may default to `bash`.

Replaces bash-specific shell command in one Makefile with a
dash-compatible alternative, and re-enables the affected Makefile test.

Removes apparently redundant definition of `UNAME`.

…yword

Unfortunately, this can't currently be tested. The problem is that we
need the file to be compiled first to then be used as dependency, which
cannot be done currently unfortunately in the rustdoc test suites.
Example:

```rust
// name this file "foo.rs"

/// ```
/// let x = foo::foo();
/// ```
pub fn foo() {}
```

If you run `rustdoc --test foo.rs`, you'll get:

```
running 1 test
test foo.rs - foo (line 1) ... FAILED

failures:

---- foo.rs - foo (line 1) stdout ----
error[E0463]: can't find crate for `foo`
 --> foo.rs:0:1
  |
2 | extern crate foo;
  | ^^^^^^^^^^^^^^^^^ can't find crate
```

If a test were possible, it would look something like

 ````rust
 #![crate_name = "mod"]
 #![crate_type = "lib"]
 //! ```
 //! // NOTE: requires that the literal string 'mod' appears in the doctest for
 //! // the bug to appear
 //! assert_eq!(1, 1);
 //! ```
 ````

Shorter code and by initializing to the final value directly, the variable
doesn't need to be mut.

Fix injected errors when running doctests on a crate named after a keyword

Closes rust-lang#79771

Allow casting mut array ref to mut ptr

Allow casting mut array ref to mut ptr

We now allow two new casts:

- mut array reference to mut ptr. Example:

      let mut x: [usize; 2] = [0, 0];
      let p = &mut x as *mut usize;

  We allow casting const array references to const pointers so not
  allowing mut references to mut pointers was inconsistent.

- mut array reference to const ptr. Example:

      let mut x: [usize; 2] = [0, 0];
      let p = &mut x as *const usize;

  This was similarly inconsistent as we allow casting mut references to
  const pointers.

Existing test 'vector-cast-weirdness' updated to test both cases.

Fixes rust-lang#24151

HWAddressSanitizer support

#  Motivation
Compared to regular ASan, HWASan has a [smaller overhead](https://source.android.com/devices/tech/debug/hwasan). The difference in practice is that HWASan'ed code is more usable, e.g. Android device compiled with HWASan can be used as a daily driver.

# Example
```
fn main() {
    let xs = vec![0, 1, 2, 3];
    let _y = unsafe { *xs.as_ptr().offset(4) };
}
```
```
==223==ERROR: HWAddressSanitizer: tag-mismatch on address 0xefdeffff0050 at pc 0xaaaad00b3468
READ of size 4 at 0xefdeffff0050 tags: e5/00 (ptr/mem) in thread T0
    #0 0xaaaad00b3464  (/root/main+0x53464)
    rust-lang#1 0xaaaad00b39b4  (/root/main+0x539b4)
    rust-lang#2 0xaaaad00b3dd0  (/root/main+0x53dd0)
    rust-lang#3 0xaaaad00b61dc  (/root/main+0x561dc)
    rust-lang#4 0xaaaad00c0574  (/root/main+0x60574)
    rust-lang#5 0xaaaad00b6290  (/root/main+0x56290)
    rust-lang#6 0xaaaad00b6170  (/root/main+0x56170)
    rust-lang#7 0xaaaad00b3578  (/root/main+0x53578)
    rust-lang#8 0xffff81345e70  (/lib64/libc.so.6+0x20e70)
    rust-lang#9 0xaaaad0096310  (/root/main+0x36310)

[0xefdeffff0040,0xefdeffff0060) is a small allocated heap chunk; size: 32 offset: 16
0xefdeffff0050 is located 0 bytes to the right of 16-byte region [0xefdeffff0040,0xefdeffff0050)
allocated here:
    #0 0xaaaad009bcdc  (/root/main+0x3bcdc)
    rust-lang#1 0xaaaad00b1eb0  (/root/main+0x51eb0)
    rust-lang#2 0xaaaad00b20d4  (/root/main+0x520d4)
    rust-lang#3 0xaaaad00b2800  (/root/main+0x52800)
    rust-lang#4 0xaaaad00b1cf4  (/root/main+0x51cf4)
    rust-lang#5 0xaaaad00b33d4  (/root/main+0x533d4)
    rust-lang#6 0xaaaad00b39b4  (/root/main+0x539b4)
    rust-lang#7 0xaaaad00b61dc  (/root/main+0x561dc)
    rust-lang#8 0xaaaad00b3578  (/root/main+0x53578)
    rust-lang#9 0xaaaad0096310  (/root/main+0x36310)

Thread: T0 0xeffe00002000 stack: [0xffffc0590000,0xffffc0d90000) sz: 8388608 tls: [0xffff81521020,0xffff815217d0)
Memory tags around the buggy address (one tag corresponds to 16 bytes):
  0xfefcefffef80: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffef90: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffefa0: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffefb0: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffefc0: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffefd0: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffefe0: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefcefffeff0: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
=>0xfefceffff000: a2  a2  05  00  e5 [00] 00  00  00  00  00  00  00  00  00  00
  0xfefceffff010: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff020: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff030: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff040: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff050: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff060: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff070: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
  0xfefceffff080: 00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
Tags for short granules around the buggy address (one tag corresponds to 16 bytes):
  0xfefcefffeff0: ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..
=>0xfefceffff000: ..  ..  c5  ..  .. [..] ..  ..  ..  ..  ..  ..  ..  ..  ..  ..
  0xfefceffff010: ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..  ..
See https://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html#short-granules for a description of short granule tags
Registers where the failure occurred (pc 0xaaaad00b3468):
    x0  e500efdeffff0050  x1  0000000000000004  x2  0000ffffc0d8f5a0  x3  0200efff00000000
    x4  0000ffffc0d8f4c0  x5  000000000000004f  x6  00000ffffc0d8f36  x7  0000efff00000000
    x8  e500efdeffff0050  x9  0200efff00000000  x10 0000000000000000  x11 0200efff00000000
    x12 0200effe000006b0  x13 0200effe000006b0  x14 0000000000000008  x15 00000000c00000cf
    x16 0000aaaad00a0afc  x17 0000000000000003  x18 0000000000000001  x19 0000ffffc0d8f718
    x20 ba00ffffc0d8f7a0  x21 0000aaaad00962e0  x22 0000000000000000  x23 0000000000000000
    x24 0000000000000000  x25 0000000000000000  x26 0000000000000000  x27 0000000000000000
    x28 0000000000000000  x29 0000ffffc0d8f650  x30 0000aaaad00b3468
```

# Comments/Caveats
* HWASan is only supported on arm64.
* I'm not sure if I should add a feature gate or piggyback on the existing one for sanitizers.
* HWASan requires `-C target-feature=+tagged-globals`. That flag should probably be set transparently to the user. Not sure how to go about that.

# TODO
* Need more tests.
* Update documentation.
* Fix symbolization.
* Integrate with CI

…ark-Simulacrum

Don't release Miri if its tests only failed on Windows

Extends rust-lang#66053 to Windows, so the released Miri won't be broken if its tests only fail on Windows.

Relevant Zulip thread: https://rust-lang.zulipchat.com/#narrow/stream/269128-miri/topic/Miri.20is.20still.20available.20in.20rustup.20today.3F

Ensures `make` tests run under /bin/dash (if available), like CI, and fixes a Makefile

Note: This cherrypicks rust-lang#81688 (`@pnkfelix)`

Updates `tools.mk` to explicitly require `SHELL := /bin/dash`, since CI uses `dash` but other environments (including developer local machines) may default to `bash`.

Replaces bash-specific shell command in one Makefile with a dash-compatible alternative, and re-enables the affected Makefile test.

Removes apparently redundant definition of `UNAME`.

Also see: [zulip discussion thread](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/how.20to.20run.2Fbless.20src.2Ftest.2Frun-make-fulldeps.2Fcoverage.20.3F)

r? `@pnkfelix`

FYI: `@wesleywiser` `@tmandry`

…pecialization-panic-safety, r=KodrAus

Increment `self.index` before calling `Iterator::self.a.__iterator_ge…

…`t_unchecked` in `Zip` `TrustedRandomAccess` specialization

Otherwise if `Iterator::self.a.__iterator_get_unchecked` panics the
index would not have been incremented yet and another call to
`Iterator::next` would read from the same index again, which is not
allowed according to the API contract of `TrustedRandomAccess` for
`!Clone`.

Fixes rust-lang#81740

use RWlock when accessing os::env

Multiple threads modifying the current process environment is fairly uncommon. Optimize for the more common read case.

r? ```@m-ou-se```

…komatsakis

GAT/const_generics: Allow with_opt_const_param to return GAT param def_id

Fixes rust-lang#75415
Fixes rust-lang#79666
cc ``@lcnr``

I've absolutely no idea who to r?  for this...

Push a `char` instead of a `str` with len one into a String

`@rustbot` modify labels +C-cleanup +T-compiler

Remove unnecessary lint allow attrs on example

It seems they are not needed anymore.

Use `Iterator::all` instead of open-coding it

Shorter code and by initializing to the final value directly, the variable
doesn't need to be mut.