trait-based structural match implementation
Moves from using a `#[structural_match]` attribute to using a marker trait (or pair of such traits, really) instead.
Fix#63438.
(This however does not remove the hacks that I believe were put into place to support the previous approach of injecting the attribute based on the presence of both derives... I have left that for follow-on work.)
Redesign the interface to the unikernel HermitCore
We are developing the unikernel HermitCore, where the kernel is written in Rust and is already part of the Rust Standard Library. The interface between the standard library and the kernel based on a small C library. With this pull request, we remove completely the dependency to C and use lld as linker. Currently, the kernel will be linked to the application as static library, which is published at https://github.com/hermitcore/libhermit-rs.
We don’t longer support the C interface to the kernel. Consequently, we remove this part from the Rust Standard Library.
Rollup of 8 pull requests
Successful merges:
- #65743 (rustc_typeck: don't record direct callees in generator_interior.)
- #65761 (libsyntax: Enhance documentation of the AST module)
- #65772 (Remove the last remaining READMEs)
- #65773 (Increase spacing for suggestions in diagnostics)
- #65791 (Adding doc on keyword continue)
- #65824 (rustc: make DefPathData (and friends) Copy (now that it uses Symbol).)
- #65828 (Derive Eq and Hash for SourceInfo again)
- #65842 (Add more information on rustdoc search)
Failed merges:
- #65825 (rustc: use IndexVec<DefIndex, T> instead of Vec<T>.)
r? @ghost
Increase spacing for suggestions in diagnostics
Make the spacing between the code snippet and verbose structured
suggestions consistent with note and help messages.
r? @Centril
libsyntax: Enhance documentation of the AST module
This PR enhances documentation state to the `libsyntax/ast.rs` (as initiative caused by [rustc-guide#474](https://github.com/rust-lang/rustc-guide/issues/474)), by adding:
- Module documentation.
- Doc-comments (and a bit of usual comments) in non-obvious (as for me) places.
- Minor style fixes to improve module readability.
rustc_typeck: don't record direct callees in generator_interior.
For expressions like `f(g().await)` we were recording `f` as needing to be kept in a temporary (and therefore be tracked by the generator type) across the suspend, even if a function/method path.
However, this is never needed, and can cause issues with complex function types (see #65244).
cc @Zoxc @nikomatsakis
rustc_mir: double-check const-promotion candidates for sanity.
Previously, const promotion involved tracking information about the value in a MIR local (or any part of the computation leading up to that value), aka "qualifs", in a quite stateful manner, which is hard to extend to arbitrary CFGs without a dataflow pass.
However, the nature of the promotion we do is that it's effectively an SSA-like "tree" (or DAG, really), of assigned-once locals - which is how we can take them from the original MIR in the first place.
This structure means that the subset of the MIR responsible for computing any given part of a const-promoted value is readily analyzable by walking that tree/DAG.
This PR implements such an analysis in `promote_consts`, reusing the `HasMutInterior` / `NeedsDrop` computation from `qualify_consts`, but reimplementing the equivalent of `IsNotPromotable` / `IsNotImplicitlyPromotable`.
Eventually we should be able to remove `IsNotPromotable` / `IsNotImplicitlyPromotable` from `qualify_consts`, which will simplify @ecstatic-morse's dataflow-based const-checking efforts.
But currently this is mainly for a crater check-only run - it will compare the results from the old promotion collection and the new promotion validation and ICE if they don't match.
r? @oli-obk
SGX: Clear additional flag on enclave entry
An attacker could set both the AC flag in CR0 as in rflags. This causes the enclave to perform an AEX upon a misaligned memory access, and an attacker learns some information about the internal enclave state.
The AC flag in rflags is copied from userspace upon an enclave entry. Upon AEX it is copied and later restored. This patch forces the rflag.AC bit to be reset right after an enter.
self-profiling: Update measureme to 0.4.0 and remove non-RAII methods from profiler.
This PR removes all non-RAII based profiling methods from `SelfProfilerRef` 🎉
It also delegates the `TimingGuard` implementation to `measureme`, now that that is available there.
r? @wesleywiser
Insurance policy in case `iter.size_hint()` lies.
Follow up to https://github.com/rust-lang/rust/pull/64949/files#r334235076.
(If the perf impact is bad we can use `debug_assert!` instead.)
The good news is that the UI tests pass locally so `iter.size_hint()` seems to be honest *thus far*.
On the other hand, with the status quo we do not have an insurance policy should that change in some case. This is problematic because a) this could possibly make some program be accepted which shouldn't, b) the compiler itself could have memory unsafety if the correctness of the iterator is assumed in `unsafe { ... }` code (even though the blame lies with the `unsafe { ... }` block in question.)
r? @RalfJung
cc @nnethercote
(Or more precisely, a pair of such traits: one for `derive(PartialEq)` and one
for `derive(Eq)`.)
((The addition of the second marker trait, `StructuralEq`, is largely a hack to
work-around `fn (&T)` not implementing `PartialEq` and `Eq`; see also issue
rust-lang/rust#46989; otherwise I would just check if `Eq` is implemented.))
Note: this does not use trait fulfillment error-reporting machinery; it just
uses the trait system to determine if the ADT was tagged or not. (Nonetheless, I
have kept an `on_unimplemented` message on the new trait for structural_match
check, even though it is currently not used.)
Note also: this does *not* resolve the ICE from rust-lang/rust#65466, as noted
in a comment added in this commit. Further work is necessary to resolve that and
other problems with the structural match checking, especially to do so without
breaking stable code (adapted from test fn-ptr-is-structurally-matchable.rs):
```rust
fn r_sm_to(_: &SM) {}
fn main() {
const CFN6: Wrap<fn(&SM)> = Wrap(r_sm_to);
let input: Wrap<fn(&SM)> = Wrap(r_sm_to);
match Wrap(input) {
Wrap(CFN6) => {}
Wrap(_) => {}
};
}
```
where we would hit a problem with the strategy of unconditionally checking for
`PartialEq` because the type `for <'a> fn(&'a SM)` does not currently even
*implement* `PartialEq`.
----
added review feedback:
* use an or-pattern
* eschew `return` when tail position will do.
* don't need fresh_expansion; just add `structural_match` to appropriate `allow_internal_unstable` attributes.
also fixed example in doc comment so that it actually compiles.
