Rollup of 12 pull requests
Successful merges:
- #89954 (Fix legacy_const_generic doc arguments display)
- #91321 (Handle placeholder regions in NLL type outlive constraints)
- #91329 (Fix incorrect usage of `EvaluatedToOk` when evaluating `TypeOutlives`)
- #91364 (Improve error message for incorrect field accesses through raw pointers)
- #91387 (Clarify and tidy up explanation of E0038)
- #91410 (Move `#![feature(const_precise_live_drops)]` checks earlier in the pipeline)
- #91435 (Improve diagnostic for missing half of binary operator in `if` condition)
- #91444 (disable tests in Miri that take too long)
- #91457 (Add additional test from rust issue number 91068)
- #91460 (Document how `last_os_error` should be used)
- #91464 (Document file path case sensitivity)
- #91466 (Improve the comments in `Symbol::interner`.)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Move `#![feature(const_precise_live_drops)]` checks earlier in the pipeline
Should mitigate the issues found during MCP on #73255.
Once this is done, we should clean up the queries a bit, since I think `mir_drops_elaborated_and_const_checked` can be merged back into `mir_promoted`.
Fixes#90770.
cc ``@rust-lang/wg-const-eval``
r? ``@nikomatsakis`` (since they reviewed #71824)
Cleanup: Eliminate ConstnessAnd
This is almost a behaviour-free change and purely a refactoring. "almost" because we appear to be using the wrong ParamEnv somewhere already, and this is now exposed by failing a test using the unstable `~const` feature.
We most definitely need to review all `without_const` and at some point should probably get rid of many of them by using `TraitPredicate` instead of `TraitRef`.
This is a continuation of https://github.com/rust-lang/rust/pull/90274.
r? `@oli-obk`
cc `@spastorino` `@ecstatic-morse`
CTFE: support assert_zero_valid and assert_uninit_valid
This ensures the implementation of all three type-based assert_ intrinsics remains consistent in Miri.
`assert_inhabited` recently got stabilized in https://github.com/rust-lang/rust/pull/90896 (meaning stable `const fn` can call it), so do the same with these other intrinsics.
Cc ```@rust-lang/wg-const-eval```
Nothing else makes sense, and there is no "danger" in doing so, as it only does something if there are const bounds, which are unstable. This used to happen implicitly via the inferctxt before, which was much more fragile.
Perform Sync check on static items in wf-check instead of during const checks
r? `@RalfJung`
This check is solely happening on the signature of the static item and not on its body, therefor it belongs into wf-checking instead of const checking.
Make `TypeFolder::fold_*` return `Result`
Implements rust-lang/compiler-team#432.
Initially this is just a rebase of `@LeSeulArtichaut's` work in #85469 (abandoned; see https://github.com/rust-lang/rust/pull/85485#issuecomment-908781112). At that time, it caused a regression in performance that required some further exploration... with this rebased PR bors can hopefully report some perf analysis from which we can investigate further (if the regression is indeed still present).
r? `@jackh726` cc `@nikomatsakis`
Implement `clone_from` for `State`
Data flow engine uses `clone_from` for domain values. Providing an
implementation of `clone_from` will avoid some intermediate memory
allocations.
Extracted from #90413.
r? `@oli-obk`
fix CTFE/Miri simd_insert/extract on array-style repr(simd) types
The changed test would previously fail since `place_index` would just return the only field of `f32x4`, i.e., the array -- rather than *indexing into* the array which is what we have to do.
The new helper methods will also be needed for https://github.com/rust-lang/miri/issues/1912.
r? ``````@oli-obk``````
Refactor single variant `Candidate` enum into a struct
`Candidate` enum has only a single `Ref` variant. Refactor it into a
struct and reduce overall indentation of the code by two levels.
No functional changes.
require full validity when determining the discriminant of a value
This resolves (for now) the semantic question that came up in https://github.com/rust-lang/rust/pull/89764: arguably, reading the discriminant of a value is 'using' that value, so we are in our right to demand full validity. Reading a discriminant is somewhat special in that it works for values of *arbitrary* type; all the other primitive MIR operations work on specific types (e.g. `bool` or an integer) and basically implicitly require validity as part of just "doing their job".
The alternative would be to just require that the discriminant itself is valid, if any -- but then what do we do for types that do not have a discriminant, which kind of validity do we check? [This code](81117ff930/compiler/rustc_codegen_ssa/src/mir/place.rs (L206-L215)) means we have to at least reject uninhabited types, but I would rather not special case that.
I don't think this can be tested in CTFE (since validity is not enforced there), I will add a compile-fail test to Miri:
```rust
#[allow(enum_intrinsics_non_enums)]
fn main() {
let i = 2u8;
std::mem::discriminant(unsafe { &*(&i as *const _ as *const bool) }); // UB
}
```
(I tried running the check even on the CTFE machines, but then it runs during ConstProp and that causes all sorts of problems. We could run it for ConstEval but not ConstProp, but that simply does not seem worth the effort currently.)
r? ``@oli-obk``
Stabilize `const_raw_ptr_deref` for `*const T`
This stabilizes dereferencing immutable raw pointers in const contexts.
It does not stabilize `*mut T` dereferencing. This is behind the
same feature gate as mutable references.
closes https://github.com/rust-lang/rust/issues/51911
Change the Miri engine to allow configuring whether to check
initialization of integers and floats. This allows the Miri tool to
optionally check for initialization if requested by the user.
Type inference for inline consts
Fixes#78132Fixes#78174Fixes#81857Fixes#89964
Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure.
Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts.
The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure.
With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME.
Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck).
cc `````@spastorino````` `````@lcnr`````
r? `````@nikomatsakis`````
`````@rustbot````` label A-inference F-inline_const T-compiler
This stabilizes dereferencing immutable raw pointers in const contexts.
It does not stabilize `*mut T` dereferencing. This is placed behind the
`const_raw_mut_ptr_deref` feature gate.
`Candidate` enum has only a single `Ref` variant. Refactor it into a
struct and reduce overall indentation of the code by two levels.
No functional changes.
The exact set of permissions granted when forming a raw reference is
currently undecided https://github.com/rust-lang/rust/issues/56604.
To avoid presupposing any particular outcome, adjust the const
qualification to be compatible with decision where raw reference
constructed from `addr_of!` grants mutable access.
Use type based qualification for unions
Union field access is currently qualified based on the qualification of
a value previously assigned to the union. At the same time, every union
access transmutes the content of the union, which might result in a
different qualification.
For example, consider constants A and B as defined below, under the
current rules neither contains interior mutability, since a value used
in the initial assignment did not contain `UnsafeCell` constructor.
```rust
#![feature(untagged_unions)]
union U { i: u32, c: std::cell::Cell<u32> }
const A: U = U { i: 0 };
const B: std::cell::Cell<u32> = unsafe { U { i: 0 }.c };
```
To avoid the issue, the changes here propose to consider the content of
a union as opaque and use type based qualification for union types.
Fixes#90268.
`@rust-lang/wg-const-eval`
Consider indirect mutation during const qualification dataflow
Previously a local would be qualified if either one of two separate data
flow computations indicated so. First determined if a local could
contain the qualif, but ignored any forms of indirect mutation. Second
determined if a local could be mutably borrowed (and so indirectly
mutated), but which in turn ignored the qualif.
The end result was incorrect because the effect of indirect mutation was
effectivelly ignored in the all but the final stage of computation.
In the new implementation the indirect mutation is directly incorporated
into the qualif data flow. The local variable becomes immediately
qualified once it is mutably borrowed and borrowed place type can
contain the qualif.
In general we will now reject additional programs, program that were
prevously unintentionally accepted.
There are also some cases which are now accepted but were previously
rejected, because previous implementation didn't consider whether
borrowed place could have the qualif under the consideration.
Fixes#90124.
r? `@ecstatic-morse`
Union field access is currently qualified based on the qualification of
a value previously assigned to the union. At the same time, every union
access transmutes the content of the union, which might result in a
different qualification.
For example, consider constants A and B as defined below, under the
current rules neither contains interior mutability, since a value used
in the initial assignment did not contain `UnsafeCell` constructor.
```rust
#![feature(untagged_unions)]
union U { i: u32, c: std::cell::Cell<u32> }
const A: U = U { i: 0 };
const B: std::cell::Cell<u32> = unsafe { U { i: 0 }.c };
```
To avoid the issue, the changes here propose to consider the content of
a union as opaque and use type based qualification for union types.
Previously a local would be qualified if either one of two separate data
flow computations indicated so. First determined if a local could
contain the qualif, but ignored any forms of indirect mutation. Second
determined if a local could be mutably borrowed (and so indirectly
mutated), but which in turn ignored the qualif.
The end result was incorrect because the effect of indirect mutation was
effectivelly ignored in the all but the final stage of computation.
In the new implementation the indirect mutation is directly incorporated
into the qualif data flow. The local variable becomes immediately
qualified once it is mutably borrowed and borrowed place type can
contain the qualif.
In general we will now reject additional programs, program that were
prevously unintentionally accepted.
There are also some cases which are now accepted but were previously
rejected, because previous implementation didn't consider whether
borrowed place could have the qualif under the consideration.
