Ignore ZST offsets when deciding whether to use Scalar/ScalarPair layout
This is important because Scalar/ScalarPair layout previously would not be used if any ZST had nonzero offset.
For example, before this change, only `((), u128)` would be laid out like `u128`, not `(u128, ())`.
Fixes#63244
perf: move cold path of `process_obligations` into a separate function
cc #76575
This probably won't matter too much in the long run once #69218 is merged so we may not want to merge this.
r? `@ecstatic-morse`
Fix#76803 miscompilation
Fixes#76803
Seems like it was an oversight that the discriminant value being set was not compared to the target value from the SwitchInt, as a comment says this is a requirement for the optimization to be sound.
r? `@wesleywiser` since you are probably familiar with the optimization and made #76837 to workaround the bug
Rollup of 15 pull requests
Successful merges:
- #75438 (Use adaptive SVG favicon for rustdoc like other rust sites)
- #76304 (Make delegation methods of `std::net::IpAddr` unstably const)
- #76724 (Allow a unique name to be assigned to dataflow graphviz output)
- #76978 (Documented From impls in std/sync/mpsc/mod.rs)
- #77044 (Liballoc bench vec use mem take not replace)
- #77050 (Typo fix: "satsify" -> "satisfy")
- #77074 (add array::from_ref)
- #77078 (Don't use an if guard to check equality with a constant)
- #77079 (Use `Self` in docs when possible)
- #77081 (Merge two almost identical match arms)
- #77121 (Updated html_root_url for compiler crates)
- #77136 (Suggest `const_mut_refs`, not `const_fn` for mutable references in `const fn`)
- #77160 (Suggest `const_fn_transmute`, not `const_fn`)
- #77164 (Remove workaround for deref issue that no longer exists.)
- #77165 (Followup to #76673)
Failed merges:
r? `@ghost`
Suggest `const_fn_transmute`, not `const_fn`
More fallout from #76850 in the vein of #77134. The fix is the same. I looked through the structured errors file and didn't see any more of this kind of diagnostics bug.
r? @oli-obk
Suggest `const_mut_refs`, not `const_fn` for mutable references in `const fn`
Resolves#77134.
Prior to #76850, most uses of `&mut` in `const fn` ~~required~~ involved two feature gates, `const_mut_refs` and `const_fn`. The first allowed all mutable borrows of locals. The second allowed only locals, arguments and return values whose types contained `&mut`. I switched the second check to the `const_mut_refs` gate. However, I forgot update the error message with the new suggestion.
Alternatively, we could revert to having two different feature gates for this. OP's code never borrows anything mutably, so it didn't need `const_mut_refs` in the past, only `const_fn`. I'd prefer to keep everything under a single gate, however.
r? @oli-obk
Allow a unique name to be assigned to dataflow graphviz output
Previously, if the same analysis were invoked multiple times in a single compilation session, the graphviz output for later runs would overwrite that of previous runs. Allow callers to add a unique identifier to each run so this can be avoided.
DroplessArena: Allocate objects from the end of memory chunk
Allocating from the end of memory chunk simplifies the alignment code
and reduces the number of checked arithmetic operations.
Add fast path for match checking
This adds a fast path that would reduce the complexity to linear on matches consisting of only variant patterns (i.e. enum matches). (Also see: #7462) Unfortunately, I was too lazy to add a similar fast path for constants (mostly for integer matches), ideally that could be added another day.
TBH, I'm not confident with the performance claims due to the fact that enums tends to be small and FxHashMap could add a lot of overhead.
r? `@Mark-Simulacrum`
needs perf
const_evaluatable_checked: extend predicate collection
We now walk the hir instead of using `ty` so that we get better spans here, While I am still not completely sure if that's
what we want in the end, it does seem a lot closer to the final goal than the previous version.
We also look into type aliases (and use a `TypeVisitor` here), about which I am not completely sure, but we will see how well this works.
We also look into fn decls, so the following should work now.
```rust
fn test<T>() -> [u8; std::mem::size_of::<T>()] {
[0; std::mem::size_of::<T>()]
}
```
Additionally, we visit the optional trait and self type of impls.
r? `@oli-obk`
Fix underflow when calculating the number of no-op jumps folded
When removing unwinds to no-op blocks and folding jumps to no-op blocks,
remove the unwind target first. Otherwise we cannot determine if target
has been already folded or not.
Previous implementation incorrectly assumed that all resume targets had
been folded already, occasionally resulting in an underflow:
```
remove_noop_landing_pads: removed 18446744073709551613 jumps and 3 landing pads
```
Rollup of 9 pull requests
Successful merges:
- #76898 (Record `tcx.def_span` instead of `item.span` in crate metadata)
- #76939 (emit errors during AbstractConst building)
- #76965 (Add cfg(target_has_atomic_equal_alignment) and use it for Atomic::from_mut.)
- #76993 (Changing the alloc() to accept &self instead of &mut self)
- #76994 (fix small typo in docs and comments)
- #77017 (Add missing examples on Vec iter types)
- #77042 (Improve documentation for ToSocketAddrs)
- #77047 (Miri: more informative deallocation error messages)
- #77055 (Add #[track_caller] to more panicking Cell functions)
Failed merges:
r? `@ghost`
MIR pass to remove unneeded drops on types not needing drop
This is heavily dependent on MIR inlining running to actually see the drop statement.
Do we want to special case replacing a call to std::mem::drop with a goto aswell?
Add cfg(target_has_atomic_equal_alignment) and use it for Atomic::from_mut.
Fixes some platform-specific problems with #74532 by using the actual alignment of the types instead of hardcoding a few `target_arch`s.
r? @RalfJung
emit errors during AbstractConst building
There changes are currently still untested, so I don't expect this to pass CI 😆
It seems to me like this is the direction we want to go in, though we didn't have too much of a discussion about this.
r? @oli-obk
Record `tcx.def_span` instead of `item.span` in crate metadata
This was missed in PR #75465. As a result, a few places have been using
the full body span of functions, instead of just the header span.
SimplifyComparisonIntegral: fix miscompilation
Fixes#76432
Only insert StorageDeads if we actually removed one.
Fixes an issue where we added StorageDead to a place with no StorageLive
r? `@oli-obk`
Remove `qualify_min_const_fn`
~~Blocked on #76807 (the first six commits).~~
With this PR, all checks in `qualify_min_const_fn` are replicated in `check_consts`, and the former is no longer invoked. My goal was to have as few changes to test output as possible, since making sweeping changes to the code *while* doing big batches of diagnostics updates turned out to be a headache. To this end, there's a few `HACK`s in `check_consts` to achieve parity with `qualify_min_const_fn`.
The new system that replaces `is_min_const_fn` is referred to as "const-stability" My end goal for the const-stability rules is this:
* Const-stability is only applicable to functions defined in `staged_api` crates.
* All functions not marked `rustc_const_unstable` are considered "const-stable".
- NB. This is currently not implemented. `#[unstable]` functions are also const-unstable. This causes problems when searching for feature gates.
- All "const-unstable" functions have an associated feature gate
* const-stable functions can only call other const-stable functions
- `allow_internal_unstable` can be used to circumvent this.
* All const-stable functions are subject to some additional checks (the ones that were unique to `qualify_min_const_fn`)
The plan is to remove each `HACK` individually in subsequent PRs. That way, changes to error message output can be reviewed in isolation.
