When positional width and precision formatting flags are present in a
formatting string that has an argument count mismatch, provide extra
information pointing at them making it easiser to understand where the
problem may lay:

```
error: 4 positional arguments in format string, but there are 3 arguments
  --> $DIR/ifmt-bad-arg.rs:78:15
   |
LL |     println!("{} {:.*} {}", 1, 3.2, 4);
   |               ^^ ^^--^ ^^      --- this parameter corresponds to the precision flag
   |                    |
   |                    this precision flag adds an extra required argument at position 1, which is why there are 4 arguments expected
   |
   = note: positional arguments are zero-based
   = note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html

error: 4 positional arguments in format string, but there are 3 arguments
  --> $DIR/ifmt-bad-arg.rs:81:15
   |
LL |     println!("{} {:07$.*} {}", 1, 3.2, 4);
   |               ^^ ^^-----^ ^^      --- this parameter corresponds to the precision flag
   |                    |  |
   |                    |  this precision flag adds an extra required argument at position 1, which is why there are 4 arguments expected
   |                    this width flag expects an `usize` argument at position 7, but there are 3 arguments
   |
   = note: positional arguments are zero-based
   = note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html

error: 3 positional arguments in format string, but there are 3 arguments
  --> $DIR/ifmt-bad-arg.rs:84:15
   |
LL |     println!("{} {:07$} {}", 1, 3.2, 4);
   |               ^^ ^^---^ ^^
   |                    |
   |                    this width flag expects an `usize` argument at position 7, but there are 3 arguments
   |
   = note: positional arguments are zero-based
   = note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html
```

Fixes rust-lang#62658.

I had one job...

…-musleabi.

Support for the targets in the compiler and std build in the CI.

Added support for armv7-unknown-linux-gnueabi/musleabi

Fixes rust-lang#63101

Some things that are not done and I hope someone can help me with:

* During the ci build of `armv7-unknown-linux-gnueabi` `openssl` must be built (to build cargo) but `openssl` does not yet support this target. This feels slightly like a chicken-and-egg problem, any feedback is welcome.
* Should I add any tests for any of these targets?

…hton

On `format!()` arg count mismatch provide extra info

When positional width and precision formatting flags are present in a
formatting string that has an argument count mismatch, provide extra
information pointing at them making it easiser to understand where the
problem may lay:

```
error: 4 positional arguments in format string, but there are 3 arguments
  --> $DIR/ifmt-bad-arg.rs:78:15
   |
LL |     println!("{} {:.*} {}", 1, 3.2, 4);
   |               ^^ ^^--^ ^^      --- this parameter corresponds to the precision flag
   |                    |
   |                    this precision flag adds an extra required argument at position 1, which is why there are 4 arguments expected
   |
   = note: positional arguments are zero-based
   = note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html

error: 4 positional arguments in format string, but there are 3 arguments
  --> $DIR/ifmt-bad-arg.rs:81:15
   |
LL |     println!("{} {:07$.*} {}", 1, 3.2, 4);
   |               ^^ ^^-----^ ^^      --- this parameter corresponds to the precision flag
   |                    |  |
   |                    |  this precision flag adds an extra required argument at position 1, which is why there are 4 arguments expected
   |                    this width flag expects an `usize` argument at position 7, but there are 3 arguments
   |
   = note: positional arguments are zero-based
   = note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html

error: invalid reference to positional argument 7 (there are 3 arguments)
  --> $DIR/ifmt-bad-arg.rs:84:18
   |
LL |     println!("{} {:07$} {}", 1, 3.2, 4);
   |                  ^^^--^
   |                     |
   |                     this width flag expects an `usize` argument at position 7, but there are 3 arguments
   |
   = note: positional arguments are zero-based
   = note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html
```

Fix rust-lang#49384.

build_helper: try less confusing method names

build_helper's `*_silent` methods were likely called that way because they do not print the command being run to stdout. [In the original file this all makes sense](rust-lang@046e687#diff-5c3d6537a43ecae03014e118a7fe3321). But later it also gained `*_suppressed` methods and the difference between `silent` and `suppressed` is far from clear.

So rename `run` (which prints the command being run) to `run_verbose`. Then we can call the methods that just run a command and show its output but nothing extra `run` and `try_run`.

`run_verbose` (formerly `run`) is unused from what I can tell. Should I remove it?

r? @alexcrichton
Cc @Mark-Simulacrum
Also see rust-lang#63089 (comment).

remove unsupported test case

r? @alexcrichton

Round generator sizes to a multiple of their alignment

Fixes rust-lang#62658.

r? @cramertj
cc @eddyb

…twco

Pretty print attributes in `print_arg`

Fixes rust-lang#63210.
cc rust-lang#60406

r? @petrochenkov

Clarify semantics of mem::zeroed

Clarifies the semantics of `mem::zeroed`.

r? @Centril

cc @RalfJung