add 'project' process guidlines for larger contributions
Fixes https://github.com/rust-lang/miri/issues/3443
I am honestly not entirely sure what the consensus from what issue was. I feel like the epoll PR worked reasonably well, and not having been closely involved I am not sure which process `@oli-obk` followed there. Compared to the first draft in #3443 I tried to make this less formal and framed more as guidelines than hard rules.
FD: remove big surrounding RefCell, simplify socketpair
A while ago, I added the big implicit RefCell for all file descriptions since it avoided interior mutability in `eventfd`. However, this requires us to hold the RefCell "lock" around the entire invocation of the `read`/`write` methods on an FD, which is not great. For instance, if an FD wants to update epoll notifications from inside its `read`/`write`, it is very crucial that the notification check does not end up accessing the FD itself. Such cycles, however, occur naturally:
- eventfd wants to update notifications for itself
- socketfd wants to update notifications on its "peer", which will in turn check *its* peer to see whether that buffer is empty -- and my peer's peer is myself.
This then also lets us simplify socketpair, which currently holds a weak reference to its peer *and* a weak reference to the peer's buffer -- that was previously needed precisely to avoid this issue.
Make unused states of Reserved unrepresentable
In the [previous TB update](https://github.com/rust-lang/miri/pull/3742) we discovered that the existence of `Reserved + !ty_is_freeze + protected` is undesirable.
This has the side effect of making `Reserved { conflicted: true, ty_is_freeze: false }` unreachable.
As such it is desirable that this state would also be unrepresentable.
This PR eliminates the unused configuration by changing
```rs
enum PermissionPriv {
Reserved { ty_is_freeze: bool, conflicted: bool },
...
}
```
into
```rs
enum PermissionPriv {
ReservedFrz { conflicted: bool },
ReservedIM,
...
}
```
but this is not the only solution and `Reserved(Activable | Conflicted | InteriorMut)` could be discussed.
In addition to making the unreachable state not representable anymore, this change has the nice side effect of enabling `foreign_read` to no longer depend explicitly on the `protected` flag.
Currently waiting for
- `@JoJoDeveloping` to confirm that this is the same representation of `Reserved` as what is being implemented in simuliris,
- `@RalfJung` to approve that this does not introduce too much overhead in the trusted codebase.
Implement epoll shim
This PR:
- implemented non-blocking ``epoll`` for #3448 . The design for this PR is documented in https://hackmd.io/`@tiif/SJatftrH0` .
- renamed FileDescriptor to FileDescriptionRef
- assigned an ID to every file description
Migrate `min-global-align` and `no-alloc-shim` `run-make` tests to rmake
Part of #121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).
Please try:
try-job: aarch64-apple
try-job: test-various
try-job: armhf-gnu
try-job: aarch64-gnu
try-job: aarch64-gnu
Rollup of 6 pull requests
Successful merges:
- #128570 (Stabilize `asm_const`)
- #128828 (`-Znext-solver` caching)
- #128954 (Explicitly specify type parameter on FromResidual for Option and ControlFlow.)
- #129059 (Record the correct target type when coercing fn items/closures to pointers)
- #129071 (Port `run-make/sysroot-crates-are-unstable` to rmake)
- #129088 (Make the rendered html doc for rustc better)
r? `@ghost`
`@rustbot` modify labels: rollup
Port `run-make/sysroot-crates-are-unstable` to rmake
I already have a more elaborate draft at #126231 that tries to port the underlying Python script to rmake, but there's no need for the removal of Makefiles to be held up on complex tasks like that, so this PR simply takes the trivial Makefile and converts it into a trivial rmake recipe.
Part of #121876.
r? ``@jieyouxu``
Rollup of 7 pull requests
Successful merges:
- #122884 (Optimize integer `pow` by removing the exit branch)
- #127857 (Allow to customize `// TODO:` comment for deprecated safe autofix)
- #129034 (Add `#[must_use]` attribute to `Coroutine` trait)
- #129049 (compiletest: Don't panic on unknown JSON-like output lines)
- #129050 (Emit a warning instead of an error if `--generate-link-to-definition` is used with other output formats than HTML)
- #129056 (Fix one usage of target triple in bootstrap)
- #129058 (Add mw back to review rotation)
r? `@ghost`
`@rustbot` modify labels: rollup
Add windows-targets crate to std's sysroot
With this PR, when backtrace is used as a crate from crates.io it will (once updated) use the real [windows-targets](https://crates.io/crates/windows-targets) crate. But when used from std it'll use std's replacement version.
This allows sharing our customized `windows_tagets::link!` macro between std proper and the backtrace crate when used as part of std, ensuring a consistent linking story. This will be especially important once we move to using [`raw-dylib`](https://doc.rust-lang.org/reference/items/external-blocks.html#dylib-versus-raw-dylib) by default.
Migrate `remap-path-prefix-dwarf` `run-make` test to rmake
Part of #121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).
Possibly my proudest branch name yet.
try-job: aarch64-apple
try-job: armhf-gnu
try-job: test-various
try-job: x86_64-gnu-llvm-18
Shrink `TyKind::FnPtr`.
By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and `FnHeader`, which can be packed more efficiently. This reduces the size of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms. This reduces peak memory usage by a few percent on some benchmarks. It also reduces cache misses and page faults similarly, though this doesn't translate to clear cycles or wall-time improvements on CI.
r? `@compiler-errors`
compiletest: Don't panic on unknown JSON-like output lines
The `json::extract_rendered` function is called for both compiler output and non-compiler output, so it's inappropriate to panic just because a line starting with `{` didn't contain a compiler output message.
It is called from two places: when checking the output of a `ui` test process, and when printing the output of an arbitrary non-passing `ProcRes`. So unfortunately there's currently no easy way to know for sure whether it is seeing compiler output or not. Fortunately, neither call site appears to be relying on this panic; it's just an overzealous internal check.
Fixes#126373.
Borrow tracking: remove the concept of a call ID
Turns out this is not needed any more ever since we started tracking the `protected_tags` list in the per-frame state.
Also thanks to `@JoJoDeveloping` for inspiring me to even consider this possibility. :)
Fix blessing of rmake tests
Fixes#129038.
When running in `--bless` mode, we now set the value of `RUSTC_BLESS_TEST` to the current test's source directory. This allows the diff helper in `run_make_support` to find the original snapshot file in the source directory and bless that, instead of unhelpfully blessing the temporary copy in `build`.
r? `@jieyouxu`
