Signed-off-by: onur-ozkan <[email protected]>

Co-authored-by: Ookiineko <[email protected]>

Signed-off-by: onur-ozkan <[email protected]>

Use the existing Lemire (decimal -> float) and Dragon / Grisu algorithms
(float -> decimal) to add support for `f16`. This allows updating the
implementation for `Display` to the expected behavior for `Display`
(currently it prints the a hex bitwise representation), matching other
floats, and adds a `FromStr` implementation.

In order to avoid crashes when compiling with Cranelift or on targets
where f16 is not well supported, a fallback is used if
`cfg(target_has_reliable_f16)` is not true.

Extend the existing tests for `f32` and `f64` with versions that include
`f16`'s new printing and parsing implementations.

Co-authored-by: Speedy_Lex <[email protected]>

This requires a fix to the subnormal test to cap the maximum allowed
value within the maximum mantissa.

…Simulacrum

Add `f16` formatting and parsing

Use the same algorithms as for `f32` and `f64` to implement `f16` parsing and printing.

try-job: aarch64-gnu
try-job: dist-s390x-linux
try-job: x86_64-mingw-1
try-job: x86_64-mingw-2

Cygwin support in rustc

This PR builds host rustc targeting cygwin.

- [x] rust-lang/stacker#122
- [x] nagisa/rust_libloading#173
- [x] Detegr/rust-ctrlc#131
- [x] rust-random/getrandom#654
- [x] msys2/MSYS2-packages#5350
- [x] rust-lang#140886
- [x] rust-lang#140921
- [x] rust-lang#140973

Currently supported:
* rustc
* rustdoc
* rustfmt
* clippy

Blocking:
* cargo: blocked by rust-lang/socket2#568
* rust-analyzer: needs `cargo update`, fixed upstream

```
$ rustc --version --verbose
rustc 1.88.0-dev
binary: rustc
commit-hash: unknown
commit-date: unknown
host: x86_64-pc-cygwin
release: 1.88.0-dev
LLVM version: 20.1.4
```

…imulacrum

std: stop using TLS in signal handler

TLS is not async-signal-safe, making its use in the signal handler used to detect stack overflows unsound (c.f. rust-lang#133698). POSIX however lists two thread-specific identifiers that can be obtained in a signal handler: the current `pthread_t` and the address of `errno`. Since `pthread_equal` is not AS-safe, `pthread_t` should be considered opaque, so for our purposes, `&errno` is the only option. This however works nicely: we can use the address as a key into a map that stores information for each thread. This PR uses a `BTreeMap` protected by a spin lock to hold the guard page address and thread name and thus fixes rust-lang#133698.

Remove #![feature(let_chains)] from library and src/librustdoc

PR rust-lang#132833 has stabilized the `let_chains` feature. This PR removes the last occurences from the library, the compiler, and librustdoc (also because rust-lang#140887 missed the conditional in one of the crates as it was behind the "rustc" feature).

We keep `core` as exercise for the future as updating it is non-trivial (see PR thread).

…larsan68

replace `cc_detect::cc2ar` with `cc::try_get_archiver`

~~Awaiting new release of [cc](https://crates.io/crates/cc) version with rust-lang/cc-rs#1456 to bump the version.~~

~~Blocked by rust-lang/cc-rs#1456

Kind a self-explanatory.

…rsan68,jieyouxu

bump windows crate for compiler,bootstrap and tools

This dedupes crate versions. For `x86_64-pc-windows-msvc` stage1 cuts few kb from `rustc_driver.dll`, nice.