This test was previously flakey on `i686-mingw`, but since some
modifications I could no longer make it fail on `i686-mingw`.

See <rust-lang#128958> for multiple try
job runs.

This is a trivial Python script that simply tries to parse each line of stdin
(i.e. the test process output) as JSON, to verify that the overall output is
JSON Lines.

We can perform the same check directly in `rmake.rs` using `serde_json`.

…r, r=nnethercote

Stabilize `unsafe_attributes`

# Stabilization report

## Summary

This is a tracking issue for the RFC 3325: unsafe attributes

We are stabilizing `#![feature(unsafe_attributes)]`,  which makes certain attributes considered 'unsafe', meaning that they must be surrounded by an `unsafe(...)`, as in `#[unsafe(no_mangle)]`.

RFC: rust-lang/rfcs#3325
Tracking issue: rust-lang#123757

## What is stabilized

### Summary of stabilization

Certain attributes will now be designated as unsafe attributes, namely, `no_mangle`, `export_name`, and `link_section` (stable only), and these attributes will need to be called by surrounding them in `unsafe(...)` syntax. On editions prior to 2024, this is simply an edition lint, but it will become a hard error in 2024. This also works in `cfg_attr`, but `unsafe` is not allowed for any other attributes, including proc-macros ones.

```rust
#[unsafe(no_mangle)]
fn a() {}

#[cfg_attr(any(), unsafe(export_name = "c"))]
fn b() {}
```

For a table showing the attributes that were considered to be included in the list to require unsafe, and subsequent reasoning about why each such attribute was or was not included, see [this comment here](rust-lang#124214 (comment))

## Tests

The relevant tests are in `tests/ui/rust-2024/unsafe-attributes` and `tests/ui/attributes/unsafe`.

…r=compiler-errors

Re-enable more debuginfo tests on Windows

These tests used to be disabled on all Windows hosts. Now they're fully enabled or just disabled on windows-gnu with an issue citation that clearly explains why.

The changes in this PR are not tested by PR CI, but I've tested it using try-jobs below.

try-job: i686-msvc
try-job: i686-mingw
try-job: x86_64-mingw
try-job: x86_64-msvc

…bank

Re-enable `dump-ice-to-disk` for Windows

This test was previously flakey on `i686-mingw` (reason unknown), but since some modifications (quarantining each ICE test in separate tmp dirs, adding/removing `RUSTC_ICE` env vars as suitable to prevent any kind of environmental influence), I could no longer make it fail on `i686-mingw`.

I tried running this test (without the `ignore-windows` of course) a bunch of times via `i686-mingw` try jobs and it refused to fail (see rust-lang#128958). I was also never able to reproduce the failure locally.

In any case, if this turns out to be still flakey on `i686-mingw`, we can revert the removal of `ignore-windows` but this time we'll have way more context for why the test failed.

Running the `i686-mingw` alongside some Windows jobs for basic santiy check. But the try jobs succeeding is insufficient to guarantee reproducibility.

cc rust-lang#129115 for backlink.

try-job: x86_64-msvc
try-job: x86_64-mingw
try-job: i686-msvc
try-job: i686-mingw

…=compiler-errors

Fix `is_val_statically_known` for floats

The LLVM intrinsic name for floats differs from the LLVM type name, so handle them explicitly. Also adds support for `f16` and `f128`.

`f16`/`f128` tracking issue: rust-lang#116909

Port `run-make/libtest-json/validate_json.py` to Rust

This is a trivial Python script that simply tries to parse each line of stdin (i.e. the test process output) as JSON, to verify that the overall output is JSON Lines.

We can perform the same check directly in `rmake.rs` using `serde_json`.

r? ```@jieyouxu```

Added f16 and f128 to tests/ui/consts/const-float-bits-conv.rs

 Fixes rust-lang#129163